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A Numerical Study on the Selection of Main Specification of the 18.5ft Bass Fishing Boat (18.5ft급 경기용 배스보트의 주요제원 선정에 관한 수치해석 연구)

  • Lim, Jun-Taek;Seo, Kwang-Cheol;Park, Geun-Hong;Kim, Sang-Won
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.7
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    • pp.945-952
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    • 2018
  • Recently, bass fishing has become a marine leisure sport in Korea. There are 4 major fishing associations in Korea, and each association holds 10-15 tournaments each year. However, supply of 17 ft bass boats, which are preferred in leagues, depends 100 % on imports. In this study, we have derived the main specifications to develop the initial hull forms of a 18.5ft bass boat through statistical analysis based on mothership data. In addition, CFD numerical analysis was carried out according to deadrise angle and longitudinal center of gravity, which strongly influenced the resistance and planing performance. For numerical analysis, design speed was set to $Fn=3.284 (Re=9.858{\times}10^7)$, the deadrise angle was set from 12 to $20^{\circ}$, and the longitudinal center of gravity was set in the range of 0 to $8%L_{wL}$ from the center of buoyancy to the stern. Based on the numerical results, we first set the range of these factors by resistance performance and immersion keel length. Furthermore, using a correlation graph of Savitsky's Drag-Lift ratio, we derived the deadrise angle ($14-16^{\circ}$) and longitudinal center of gravity ($4-6%L_{wL}$).

A Study on the Deformable Art Pavilion Spatial Expression Characteristics (가변형 아트 파빌리온 공간 표현특성에 관한연구)

  • Du, Bo-Yu;Hong, Kwan-Seon
    • The Journal of the Korea Contents Association
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    • v.19 no.8
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    • pp.23-34
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    • 2019
  • The space before modern times is fixed and closed, then that after modern times is flexible and open. Based on the concept of space, the modern art exhibition hall gradually shifts from the interior space of a building to the outdoor space, giving birth to the concept of outdoor art pavilion. Based on this background, we analyzed and learned about the latest deformable art pavilions, focused on the investigation of its space performance characteristics and the case analysis, fully understood the design principles of deformable pavilions, and proposed the basic design directions and strategies for future research. Firstly, through learning the theories of transformable space, the characteristics and concept range of deformable space are understood. Secondly, based on the preliminary research and analysis of art pavilions, the performance characteristics are summarized. Thirdly, the pattern of deformable space and the method of reflecting the characteristics of deformable space are investigated based on cases. After summarizing the case analysis, we identified the differences of different art pavilions between deformable modes and space characteristics, and analyzed the causes. This work provides a basis for distinguishing the transformation patterns of the deformable space, and reveals the changes in space concepts and the expansion of space meaning in future architectural space design.

Change Pattern of Heart Age in Korean Population Using Heart Age Predictor of Framingham Heart Study (Framingham Heart Study의 Heart Age Predictor를 활용한 한국인 심장나이 추이분석)

  • Cho, Sang Ok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.8
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    • pp.331-343
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    • 2019
  • The purpose of this study is to observe the trends of heart age of Koreans by using the predictor of heart age of the Framingham Heart Study. The subjects were 20,012 adults aged 30~74 years who were enrolled in the Korean National Health and Nutrition Examination Survey from 2005~2013. They filled in the determinants data and they had no history of cardiovascular disease (CVD). The heart age was calculated using a non-laboratory based model of prediction. The difference of heart age and chronological age, and the rate of excessive heart age over 10 years were calculated. The annual trend, the difference according to gender, the age bracket and geographic region, the heart age were all evaluated. Data analysis performed using the SAS program (version 9.3). Complex designed analysis was done. The heart age showed differences according to gender, age bracket and geographic region. The heart age is a useful comprehensive indicator for predicting the CVD events in the near future. So, it could be used for the purposes of exercising caution and guidance on CVD for administering medical care. It is strongly recommended to use heart age as an indicator for customized medical management to focus efforts on relatively vulnerable subjects and their factors for CVD. Further study on Koreans' customized heart age is needed.

A Study on Vibration & Noise Reduction of Fast Back Feeding Device for Manufacturing Process (제조공정용 Fast Back 이송장치 진동·소음 저감에 관한 연구)

  • Han, Doo-Hee;Lee, Seung-Hun;Son, Yung-Deug
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.8
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    • pp.642-648
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    • 2019
  • This paper presents a fast back-type transfer device for snack food processing that uses the inertia of transferred material. A conventional conveying system is a drive system that uses a belt conveyor and mechanical crank, which generate noise and vibration and cause environmental pollution. Vibration and noise are reduced in the proposed fast back feeding device by using a counterweight. The crank drive unit was replaced with a linear servomotor, and an equilibrium device was designed to balance the force due to acceleration. This makes it is possible to adjust the forward and backward speed and acceleration through PLC control. A vibration damper device offsets the vibration force of the periodic shock form. The main cause of the vibration was identified through vibration analysis, and reduction measures were established. We verified the effectiveness of the vibration by making a prototype and performing about 10 vibration tests. Because no mechanical transducer is needed, energy loss, noise, and vibration do not occur, and the operating speed is not limited.

Drone Deployment Using Coverage-and-Energy-Oriented Technique in Drone-Based Wireless Sensor Network (드론 기반 무선 센서 네트워크에서의 커버리지와 에너지를 고려한 드론 배치)

  • Kim, Tae-Rim;Song, Jong-Gyu;Im, Hyun-Jae;Kim, Bum-Su
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.8
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    • pp.15-22
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    • 2019
  • Awireless sensor network utilizes small sensors with a low cost and low power being deployed over a wide area. They monitor the surrounding environment and gather the associated information to transmit it to a base station via multi-hop transmission. Most of the research has mainly focused on static sensors that are located in a fixed position. Unlike a wireless sensor network based on static sensors, we can exploit drone-based technologies for more efficient wireless networks in terms of coverage and energy. In this paper, we introduce a transmission power model and a video encoding power model to design the network environment. We also explain a priority mapping scheme, and deploy drones oriented for network coverage and energy consumption. Through our simulations, this research shows coverage and energy improvements in adrone-based wireless sensor network with fewer sensors, compared to astatic sensor-based wireless sensor network. Concretely, coverage increases by 30% for thedrone-based wireless sensor network with the same number of sensors. Moreover, we save an average of 25% with respect to the total energy consumption of the network while maintaining the coverage required.

Effects of Respiratory Infectious Disease Simulation-based Education on Nursing Student's of Clinical Competency, Self-leadership and Critical Thinking (호흡기 감염병 시뮬레이션 교육이 간호대학생의 호흡기 감염병 관련 임상수행능력, 셀프리더십 및 비판적 사고에 미치는 효과)

  • Kim, Jung-Kyung;Song, Min-Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.8
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    • pp.93-101
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    • 2019
  • This study was conducted to develop a simulation-based education program for respiratory infectious disease and to identify the effects of clinical competency, self-leadership and critical thinking after applying to nursing students. A non-equivalent pre-post test of quasi-experimental design was used. The study subjects were 30 students for the experimental group and 30 for the control group. Respiratory infectious disease simulation-based education was provided for 5 weeks. Data analysis was performed using SPSS WIN Ver 21.0 with Fisher's exact test, independent t-test, and paired t-test. Clinical competency, self-leadership, and critical thinking of the experimental group showed statistically significant differences in comparison with the control group. These study results proved that a simulation-based education program for respiratory infectious disease is effective in raising nursing students' clinical competency, self-leadership and critical thinking. Therefore, it is considered that simulation-based education should be provided to cultivate nursing problem-solving clinical competency, self-leadership or critical thinking by developing a scenario based on various clinical situations.

Analysis of Epistemic Thinking in Middle School Students in an Argument-Based Inquiry(ABI) Science Class (논의기반 탐구(ABI) 과학수업에서 나타나는 중학생들의 인식론적 사고 분석)

  • Park, Jiyeon;Nam, Jeonghee
    • Journal of The Korean Association For Science Education
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    • v.39 no.3
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    • pp.337-348
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    • 2019
  • The purpose of this study is to examine epistemic thinking in middle school students in an argument-based inquiry science class. Participants of the study were 93 9th grade students from four classes of a middle school in a metropolitan city. Observations were made over one semester during which argument-based inquiry lessons on five subjects were conducted. Data was collected from argument-based inquiry activity worksheets and student questionnaires. After analysis of epistemic thinking in the written reflections, students were found to have the highest frequency of epistemic metacognitive skills, followed by epistemic cognition, epistemic metacognitive experience, and epistemic metacognitive knowledge. While investigating the effects of an argument-based inquiry science class on student epistemic thinking and after analysis of the reflections written for the first ABI activity and the fifth ABI activity, we found that all of the sub-elements of epistemic thinking have increased. The rate of growth for epistemic cognition is greatest, followed by epistemic metacognitive knowledge and epistemic metacognitive skills. Assessed for epistemic thinking, the level of epistemic thinking improved over the course of the argument-based inquiry science class. The results of the survey show that students actively participating and being recognized for their active participation in the argument-based inquiry science class are helpful in understanding scientific knowledge. Therefore, an argument-based inquiry science class is a teaching and learning program that allows students to understand and experience the epistemic nature of scientific knowledge and its construction through collaboration and agreement.

A Case Study on the Construction at Near Verge Section of Secure Objects Using Electronic Detonators (전자뇌관을 이용한 보안물건 초근접구간 시공 사례)

  • Hwang, Nam-Sun;Lee, Dong-Hee;Lim, Il-soo;Kim, Jin-soo
    • Explosives and Blasting
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    • v.37 no.2
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    • pp.22-30
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    • 2019
  • On sites where explosives are used, the effects of noise and vibration produced by the blast wave are subject to a number of operational restrictions. Recently, the number of civil complaints has increased and the standard of environmental regulations on secure goods has been greatly tighten. Therefore, work is generally carried out by machine excavation in case of close proximity of safety thing. Machine excavation methods have the advantage as reducing noise and vibration compared to blasting methods, but depending on the conditions of rock intended to be excavated, they are sometimes less constructive than planned. In general, the closer a rock type is to hard rock, the less constructible it becomes. In this paper, we are going to explain the construction of a construction section with a close proximity to a safety thing using electronic detonators. While the project site was designed with a machine excavation methods due to the close(9.9m) proximity of safety thing(the railroad), construction using electronic detonators was reviewed as an alternative method for improving rate of advance time and construction efficiency when expose to hard rock. Through blasting using electronic detonators, construction and economic efficiency were maximized while minimizing impact on surrounding safety things. Because $HiTRONIC^{TM}$, which is produced by Hanwha, has innovative stability and high explosion reliability, it is able to explode with high-precision accuracy. Electronic detonators are widely used in construction sites of railway or highway, other urban burrowing areas and large limestone mines.

Application of Eco-friendly Planning of Sinseo Innovation City in Daegu using the Analysis of Satellite Image and Field Survey (위성영상 분석과 현장조사를 통한 대구 신서혁신도시의 친환경적 도시계획의 적용 검토)

  • Kim, Jiyeong;Kim, Eun Jung
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.37 no.3
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    • pp.143-156
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    • 2019
  • The purpose of this study is to examine whether the Sinseo Innovation City of Daegu has been eco-friendly developed by analyzing changes in NDVI (Normalized Difference Vegetation Index) and LST (Land Surface Temperature) and conducting field surveys. Using Landsat satellite images, it compares NDVI and LST changes between the years of 2008 and 2018. The results of the study are as follows. First, the NDVI has decreased by 0.07 and the zLST has increased by $0.85^{\circ}C$ over the past 10 years. Second, districts with lower NDVI and higher zLST were concentrated with infrastructure with impermeable materials. Districts with higher NDVI and lower zLST were utilized urban design techniques such as permeable parking lot, green roof, and permeable pavement. Third, districts with higher NDVI and lower zLST were applied eco-friendly planning items properly by district unit plan guideline. It is meaningful to suggest planing directions and urban planning elements considering the environmental friendly development.

Study on EPB TBM performance by conducting lab-scaled excavation tests with different foam injection for artificial sand (실내 굴진 시험을 통한 폼 주입 조건에 따른 인공 사질토 지반에서 EPB TBM 굴진성능에 대한 고찰)

  • Lee, Hyobum;Shin, Dahan;Kim, Dae-Young;Shin, Young Jin;Choi, Hangseok
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.4
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    • pp.545-560
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    • 2019
  • During EPB TBM tunnelling, an appropriate application of additives such as foam and polymer is an essential factor to secure the stability of TBM as well as tunnelling performance. From the '90s, there have been many studies on the optimal injection of additives worldwidely contrary to the domestic situation. Therefore, in this paper, the foam, which is widely adopted for soil conditioning, was selected as an additive in order to investigate the effect of foam injection on TBM performance through a series of laboratory excavation tests. The excavation experiments were carried out on artificial sandy soil specimens with consideration of the variance of FIR (Foam Injection Ratio), FER (Foam Expansion Ratio) and $C_f$ (Surfactant Concentration), which indicate the amount and quality of the foam. During the tests, torque values were measured, and the workability of conditioned soil was evaluated by comparing the slump values of muck after each experiment. In addition, a weight loss of the replaceable aluminum cutter bits installed on the blade was measured to estimate the degree of abrasion. Finally, the foam injection ratio for the optimal TBM excavation for the typical soil specimen was determined by comparing the measured torque, slump value and abrasion. Note that the foam injection conditions satisfying the appropriate level of machine load, mechanical wear and workability are essential in the EPB TBM operational design.