• Title, Summary, Keyword: 유용영역 실험계획

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Sequential Feasible Domain Sampling of Kriging Metamodel by Using Penalty Function (벌칙함수 기반 크리깅메타모델의 순차적 유용영역 실험계획)

  • Lee Tae-Hee;Seong Jun-Yeob;Jung Jae-Jun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.6
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    • pp.691-697
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    • 2006
  • Metamodel, model of model, has been widely used to improve an efficiency of optimization process in engineering fields. However, global metamodels of constraints in a constrained optimization problem are required good accuracy around neighborhood of optimum point. To satisfy this requirement, more sampling points must be located around the boundary and inside of feasible region. Therefore, a new sampling strategy that is capable of identifying feasible domain should be applied to select sampling points for metamodels of constraints. In this research, we suggeste sequential feasible domain sampling that can locate sampling points likely within feasible domain by using penalty function method. To validate the excellence of feasible domain sampling, we compare the optimum results from the proposed method with those form conventional global space-filling sampling for a variety of optimization problems. The advantages of the feasible domain sampling are discussed further.

Path Planning Using an Information Grid Map for Safe Navigation (안전한 주행을 위한 정보 격자지도 기반의 경로계획)

  • Jung, Min-Kuk;Park, Joong-Tae;Song, Jae-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.6
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    • pp.623-628
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    • 2012
  • Conventional path planning methods have focused on the generation of an optimal shortest path to the goal. However, this optimal path cannot guarantee safe navigation, because it can often lead to a narrow area. Therefore, we propose a Coulomb's law-based safe path planning method that uses an information grid map. The information grid map includes four types of information: occupied, empty, guide, and dangerous areas. A safe path can be generated away from the dangerous area and close to the guide area by repulsive and attractive forces, respectively. Experiments and simulations show that the proposed method can generate paths inside the safe region and is useful for safe navigation.

Dosimetric and clinical review on the application of TOMO_edge mode (토모테라피 Edge 모드를 이용한 임상적 유용성 고찰)

  • Kim, Lizzy
    • The Journal of Korean Society for Radiation Therapy
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    • v.26 no.2
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    • pp.177-182
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    • 2014
  • Purpose : The goal of this study was to compare and analysis the dose distribution and treatment time between Tomotherapy planning with fixed jaw(FJ) and dynamic jaw(DJ). Materials and Methods : Seven patients were selected in the study including five common clinical cases(brain, head and neck(HN), lung, prostate, spine). 1) Helical Tomotherapy plans with FJ and DJ were generated with the same planning parameters such as Modulation factor, Pitch and Field width. 2) Tomo_edge plans with a larger field width were generated to compare to conventional HT delivery with fixed jaw. Dosimetric evaluation indices for target coverage are Dmin, Conformity index(CI) and for whole body including target are $V_{10%}$, $V_{25%}$, $V_{50%}$, $V_{75%}$ using Dose-volume histogram(DVH). Also, Treatment time and Cumulative MU were used for clinical review on Tomo_edge. Results : In case of using the same field width of Tomotherapy planning with FJ and DJ, the averaged variations were $V_{10%}$: -11.91%, $V_{25%}$: -7.6%, $V_{50%}$ :-4.75%, $V_{75%}$: -1.04%. Tomo_edge with a larger field width provides the averaged variations for target coverage: Dmin: -0.72%, CI: -1.25% and also shows the tendency of a sharp $V_{x%}$ decline in low dose area. The clinical improvements in the larger field width with DJ were observed in the treatment time, ranging from -51.21% to -15.11, and the Cumulative MU decrease, ranging from -57.74% to -15.31%. Conclusion : Target coverage achieved by FJ and DJ with the same field width has little differences. But integral doses on whole body efficiently decreased. Compared to the conventional HT delivery, Tomo_edge with a larger field width presents a little worse target coverage. However, it provides faster treatment delivery and improved cranial-caudal target dose conformity. Therefore, Tomo_edge mode is efficient in improving the treatment time and integral dose while maintaining comparable plan quality in clinic.

두경부암의 6MV 광자선 치료 시 표면선량 증가를 위한 Spoiler의 유용성 평가

  • 이강혁;김원택;이화중;김대영
    • The Journal of Korean Society for Radiation Therapy
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    • v.14 no.1
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    • pp.41-47
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    • 2002
  • 1.목적 두경부암(head and neck Ca)과 쇄골상부(Supraclavicular)에 6MV 광자선으로 치료 시 치료부위(Target volume)가 피부에서 대략 $1^{\sim}2mm$정도 깊이에 위치할 경우, 6MV 광자선의 선량분포는 표면선량이 낮아서 치료에 적합하지 않기 때문에 Bolus와 같이 사용하지만 Skin Sparing(피부보호)효과의 손실로 피부의 손상이 발생할 수 있다. 이러한 이유로 피부의 보호와 치료 시 표면선량의 증가를 위해 Spoiler(산란판)를 제작하여 측정 후 그 특성을 이해하고 선량의 분포를 통하여 Bolus와 비교한 후에 Spoiler의 유용성에 대해 평가하고자 하였다. 2.방법 Siemens사 선형가속기(PRIMUS)의 6MV 광자선을 사용하여 Spoiler의 사용여부 및 Spoiler의 사용 시에는 조사면의 크기를 $5{\times}5,\;7{\times}7,\;10{\times}10,\;15{\times}15,\;20{\times}20cm^2$로 하고 Spoiler와 표면과의 거리는 6, 10, 15cm로 바꾸어 가면서 물팬톰(PTW. 독일)을 이용해 깊이와 측방에 따른 선량분포를 Markus 전리함(PTW. 독일)으로 측정하였으며 전리함의 방수를 위해 씌어진 방수 캡 때문에 표면선량을 별도의 고형 팬톰으로 측정하였다. 표면의 측정선량은 전리함의 측면 벽 등에 의한 선량 측정치의 증가 현상으로 과 반응을 보였으며 이를 교정하였다. 그리고 측정된 데이터를 치료계획 시스템(Pinnacle 6.0m)으로 비교, 분석하였다. 3.결과 Spoiler의 사용 시 3cm깊이 측정선량 백분율과 Spoiler를 사용하지 않은 해당 치료 조사면의 3cm깊이 선량의 백분율에 일치하도록 하여 가상의 치료 깊이인 2mm에서 측정값을 비교하여 본 결과 조사면 $5{\times}5,\;10{\times}10,\;20{\times}20cm^2$에서 OPEN시 62, 64, $70\%$, Bolus는 97, 97, $99\%$로 Spoiler의 사용 시 표면과의 거리가 6cm에서 82, 98, $103\%$, 10cm에는 72, 89, $101\%$, 15m에 65, 79, $96\%$로 나타났으며 표면에서의 측정값을 비교하여 본 결과 OPEN시 11, 17, $27\%$, Bolus는 84, 84, $86\%$, Spoiler의 사용 시 6cm에서 40, 71, $93\%$, 10cm에는 25, 50, $81\%$, 15cm에 18, 36, $67\%$를 나타내었다. 또한 3m깊이에서의 측방 선량분포에서 Spoiler의 거리변화(6, 10cm)는 심부선량의 변화에 영향을 주지 않는 것으로 확인할 수 있었다. 그리고 위의 실험측정치를 치료계획 시스템에 입력하여 선량분포를 확인한 결과 Spoiler를 사용하는 경우 OPEN에 비해 선량분포 영역을 표면으로 끌어 올릴 수 있으며 Bolus 보다 피부 보호효과는 어느 정도 유지가 되는 것을 보여주었다. 4.결론 이와 같이 Spoiler는 Bolus와 비교하여 6MV 광자선의 build up 영역을 표면으로 증가시키는 동시에 Skin Sparing(피부보호)효과를 유지할 수 있으며 두경부암의 치료에서 Spoiler의 사용이 가능한 조건으로는 조사면이 $5{\times}5cm^2$에서 Spoiler와 표면과의 거리가 6cm일 때, $7{\times}7cm^2$에서 6cm, 10cm였고 $10{\times}10cm^2$는 10cm, 15cm로, $15{\times}15cm^2$는 15cm의 간격으로 평가되었다. 또한 $20{\times}20cm^2$의 조사면, Spoiler가 6cm 간격 인 경우 Bolus를 사용한 것 보다 더욱 높은 표면선량을 나타내었다. 그러나 Spoiler와 표면간의 거리를 다르게 함으로써 깊이에 따라 선량분포를 다양하게 나타낼 수 있기 때문에 표면선량의 증가와 피부의 보호를 위해 환자의 피부 두께, 실제 치료 부위의 깊이 등을 고려한다면 Spoiler를 사용하는 것이 bolus를 사용하는 것보다 더 유용하게 적용할 수 있을 것으로 사료된다.

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Validation on Usability of Time Domain Reflectometer for Identifying Defected Aircraft Wiring (항공기 배선 결함 식별을 위한 TDR(시간영역 반사계) 활용 적합성)

  • Kim, Su-Woong;Lee, Jang-Ryong
    • The Journal of Advanced Navigation Technology
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    • v.24 no.3
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    • pp.205-211
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    • 2020
  • Wiring defect is a major concern for safe aircraft operations. However, troubleshooting process of a wiring defect is very difficult due to extensive and complex wiring system and installed location. Recently, time domain reflectometer (TDR) equipment that enables effective defected wiring troubleshooting has been introduced. Unfortunately, TDRs have not practically adopted by most of airlines' maintenance departments because the effectiveness and usefulness of TDRs have not been verified. This study was conducted to verify if TDRs can identify the location and type of defected aircraft wiring, and whether they can be applied for troubleshooting purposes. Experimental plan was established by using various wires and connections applied to actual aircraft and the observed results were compared with the TDR operation guide. The usability of the TDR in actual aircraft wiring defect detection may be acceptable as the experimental results showed similar results to the TDR operation guide.

Mammalian Research Topics and Trends in Korea (국내 포유류 연구의 주제와 동향)

  • Ko, Byung June;Eo, Soo Hyung
    • Korean Journal of Environment and Ecology
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    • v.31 no.1
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    • pp.30-41
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    • 2017
  • Mammals in Korea have been studied in various fields such as animal science, veterinary medicine, laboratory animal science, ecology, and genetics. As the importance of biodiversity has been emphasized recently, conservation and management of mammals have attracted much public attention. However, in spite of such an increase in scientific research and public interest, it is still difficult to find a report or summary to grasp the trend of mammalian research in Korea. The purpose of this study is to provide the basic data for future plans of the detailed research area and the related policies by grasping the research trends of mammals in Korea. Using text-ming and co-word analysis, we analyzed 392 mammalian research papers published in Korean national journals as of 2015. Our results showed that the number of mammalian research papers published in Korea has gradually increased and that the research target species have also become increasingly diverse. The major research areas identified through text-mining and co-word analysis are (1) evolution/phylogenetics/genetics, (2) environmental science/ecology, (3) embryology/reproductive biology/cell biology, (4) veterinary medicine related to parasites, (5) parasitology related to rodents, (6) bacteriology/virology, (7) anatomy/cell biology/laboratory animal science, (8) veterinary science related to morphology and anatomy, (9) animal science, (10) marine mammalogy, and (11) Chiroptera (bat) research. Environmental science/ecology has been the most active field among the 11 research areas in recent times, and the proportion of research has increased sharply compared to the past. Environmental science/ecology is the core of biodiversity conservation, and as the importance of biodiversity has been emphasized in recent years, researchers' interest in mammal ecology appears to have increased. We expect that the results of this study will be useful for future research plan and related policies on mammals in Korea.

Reliability Based Design Optimization for the Pressure Recovery of Supersonic Double-Wedge Inlet (이중 쐐기형 초음속 흡입구의 압력회복률에 대한 신뢰성 기반 최적설계)

  • Lee, Chang-Hyuck;Ahn, Joong-Ki;Bae, Hyo-Gil;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.11
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    • pp.1067-1074
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    • 2010
  • In this study, RBDO(Reliability Based Design Optimization) was performed for a supersonic double-wedge inlet. By considering uncertainty of design with given design space, the pressure recovery was transformed into the probabilistic constraint while the inlet drag was considered as a deterministic objective function. To save computational analysis cost and to search good design space, Latin-Hypercube design of experiment and the Kriging model were incorporated and then RBDO was performed. Monte-Carlo simulation was performed to verify the accuracy of AFORM(Advanced First Order Reliability Method). It was found that AFORM result agreed very well with the Monte-Carlo simulation result. The system reliability was guaranteed by considering uncertainty of the design variables. In case of considering diverse uncertainty of system design, RBDO was found to be useful.

Feasibility Study of Isodose Structure Based Field-in-Field Technique for Total Body Irradiation (전신조사방사선치료 시 Isodose Structure를 이용한 Field-in-Field Technique의 유용성 평가)

  • Lee, Yoon Hee;Ban, Tae Joon;Lee, Woo Seok;Kang, Tae Young;Back, Geum Mun
    • The Journal of Korean Society for Radiation Therapy
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    • v.25 no.1
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    • pp.15-24
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    • 2013
  • Purpose: In Asan Medical Center, Two parallel opposite beams are employed for total body irradiation. Patients are required to be in supine position where two arms are attached to mid axillary line. Normally, physical compensators are required to compensate the large dose difference for different parts of body due to the different thicknesses compared to the umbilicus separation. There was the maximum dose difference up to 30% in lung and chest wall compared to the prescription dose. In order to resolve the dose discrepancy occurring on different body regions, the feasibility of using Fieid-in-Field Technique is investigated in this study. Materials and Methods: CT scan was performed to The RANDO Phantom with fabricated two arms and sent to Eclipse treatment planning system (version 10.0, Varian, USA). Conventional plan with physical lead compensator and new plan using Field-in-Field Technique were established on TPS. AAA (Anisotropic Analytical Algorithm) dose calculation algorithm was employed for two parallel opposite beams attenuation. Results: The dose difference between two methods was compared with the prescription dose. The dose distribution of chest and anterior chest wall uncovered by patient arms was 114~124% for physical lead compensator while Field-in-Field Technique gave 106~107% of the dose distribution. In-vivo dosimetry result using TLD showed that the dose distribution to the same region was 110~117% for conventional physical compensator and 104~107% for Field-in-Field Technique. Conclusion: In this study, the feasibility of using FIF technique has been investigated with fabricated arms attached Rando phantom. The dose difference was up to 17% due to the attached arms. It is shown that the dose homogeneity is within ${\pm}10%$ with the CT based 3-dimensional 4 step FIF technique. The in-vivo dosimetry result using TLD was showed that 95~107% dose distribution compared to prescription dose. It is considered that CT based 3-dimensional Field-in-Field Technique for the total body irradiation gives much homogeneous dose distribution for different body parts than the conventional physical compensator method and might be useful to evaluate the dose on each part of patient body.

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Evaluation of Usefulness on In-vivo Diode Dosimetry for Measuring the Tumor Dose of Oral Cancer Patient (구강암 환자의 종양 선량 측정을 위한 In-vivo Diode Dosimetry의 유용성 평가)

  • Na Kyung-Su;Lee Je-Hee;Park Heung-Deuk
    • The Journal of Korean Society for Radiation Therapy
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    • v.17 no.2
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    • pp.133-140
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    • 2005
  • Purpose : This test is designed to identify the validity of treatment plan by implementing real-time dosimetry by means of dose that is absorbed into PTV and OAR when preparing doses of 3D and POP plans. Materials and Methods : In treatment. error can be calculated be comparing Exp. Dose with the actual dose, which has been converted from 'the reading value obtained by placing diode detector on the area to be measured'. Same test can be repeated using Alderson-Rando phantom. Results : Errors were found: A patient(POP plan): 197.6/199=-1.2%, B patient(3D-plan): 199.9/198.7=+0.6%, C patient: 196/200=-1.5%. In addition, considering the resulted value of measuring OAR besides target-dose for C patient showed 96/200, representing does of 47%, the purpose of protection was judged to be duly accomplished. Also it was acknowledged the resulted value of -3.7% met the targeted dose within the range of ${\pm}5%$. Conclusion : Aimed for identifying the usefulness of pre-treatment dose measurement using diode detector, this test was useful to evaluate the validity of curing because it resulted in the identification of category to be protected as well as t dose. Moreover, it is thought to have great advantage in ascertaining the dose of target, dose of which is not calculated yet. Similar to L-gram before treatment, this test is thought to be very effective so that it can bring great advantages in the aspects such as validity of curing method and post-treatment plan as well.

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Feasibility study of the usefulness of SRS thermoplastic mask for head & neck cancer in tomotherapy (두경부 종양의 토모치료 시 정위적방사선수술 마스크의 유용성 평가에 대한 연구)

  • Jeon, Seong Jin;Kim, Chul Jong;Kwon, Dong Yeol;Kim, Jong Sik
    • The Journal of Korean Society for Radiation Therapy
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    • v.26 no.2
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    • pp.355-362
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    • 2014
  • Purpose : When head&neck cancer radiation therapy, thermoplastic mask is applied for patients with fixed. The purpose of this study is to evaluate usefulness of thermoplastic mask for SRS in tomotherapy by conparison with the conventional mask. Materials and Methods : Typical mask(conventional mask, C-mask) and mask for SRS are used to fix body phantom(rando phantom) on the same iso centerline, then simulation is performed. Tomotherapy plan for orbit and salivary glands is made by treatment planning system(TPS). A thick portion and a thin portion located near the treatment target relative to the mask S-mask are defined as region of interest for surface dose dosimetry. Surface dose variation depending on the type of mask was analyzed by measuring the TPS and EBT film. Results : Surface dose variation due to the type of mask from the TPS is showed in orbit and salivary glands 0.65~2.53 Gy, 0.85~1.84 Gy, respectively. In case of EBT film, -0.2~3.46 Gy, 1.04~3.02 Gy. When applied to the S-mask, in TPS and Gafchromic EBT3 film, substrantially 4.26%, 5.82% showed maximum changing trend, respectively. Conclusion : To apply S-mask for tomotherapy, surface dose is changed, but the amount is insignificant and be useful when treatment target is close critical organs because decrease inter and intra fractional variation.