• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.150-158
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• 2022

This paper presents the results of a sea trial for very long range spread spectrum underwater acoustic communication conducted in the East Sea in September 2021. Signals were collected through 8 vertical sensors, and the range between the transmitter and receiver was about 160 km. 30 bps Multi-Code Spread Spectrum (MCSS) method and 100 bps Chirp Spread Spectrum method were used for the transmitting signal generation. The results show that when the channel coding technique was not used in a single channel, the uncoded bit error rate was high, but when the Equal Gain Combining (EGC) diversity technique was used after frame synchronization in each receiving channel, the uncoded bit error rate was reduced to 0.1 or less.

• The Korean Journal of Pain
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• v.31 no.2
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• pp.125-131
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• 2018

Background: The thoracic transforaminal epidural block (TTFEB) is usually performed to treat herpes zoster or postherpetic neuralgia (PHN). Especially, multiple segmental involvements and approximate contrast medium spread range, according to volume, help to choose the proper drug volume in the transforaminal epidural block. This study investigated the contrast medium spread patterns of 1-ml to 3-ml TTFEBs. Methods: A total of 26 patients with herpes zoster or PHN were enrolled in this study. All participants received 1 ml, 2 ml, or 3 ml of contrast medium. Results were divided into Groups A, B and C based on the volume (1, 2, or 3 ml), with n = 26 for each group. After the injection of contrast medium, the spread levels were estimated in both the lateral and anteroposterior (AP) images using fluoroscopy. Results: The cephalad spread of contrast medium in the lateral image as expressed by the median (interquartile range) was 2.00 levels (1.00-2.00) for Group A, 2.50 (2.00-3.00) for Group B, and 3.00 (2.00-4.00) for Group C. The caudal spread level of contrast medium was 1.00 (1.00-2.00) for Group A, 2.00 (2.00-3.00) for Group B, and 2.00 (2.00-3.00) for Group C. There was ventral and dorsal spread of the 3-ml contrast medium injection in 88% (23/26) of cases in the lateral image. Conclusions: Injection of 3 ml of contrast medium through the foramina spread 6 levels in a cephalocaudal direction. Spread patterns revealed a cephalad preference. TTFEB resulted in dorsal and ventral spread in a high percentage of cases. This procedure may be useful for transferring drugs to the dorsal and ventral roots.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.183-189
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• 2014

Purpose : Intravenous contrast medium is a substance used to enhance the contrast of normal tissues or malignant tissues within the body. For this reason, intravenous contrast media have been extensively used form treatment-planning CT. However, when the patient is receiving proton therapy, there is no contrast medium in that moment. In this study, evaluate the influence of intravenous contrast medium on proton range and Spread-Out Bragg peak(SOBP) in Treatment Planning System(TPS). Materials and Methods : Hounsfield Unit(HU) value were measured by 20 liver cancer patients with phase change. and evaluate the proton range and SOBP on 5 liver proton treatment plan. By using the hand made water phantom measure the proton range and SOBP on proton treatment plan with changing HU and Depth. Results : Changing value(Pre contrast, Arterial phase, Portal phase) in liver cancer patient were ($58{\pm}5.7$, $75{\pm}9.5$, $117{\pm}14.6$ for liver tissue) and ($40{\pm}6.1$, $279{\pm}49.0$, $154{\pm}22.8$ for aorta), respectively. The mean difference of range was 2.5mm and SOBP was 1.4mm according to HU change. In phantom study, proton range was shorter and SOBP was narrowed with increasing HU. Conclusion : We verify that HU change lead to range and SOBP change in TPS. Additional study is required to verify that change of HU make range and SOBP be changed in actual substance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.308-308
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• 2010

실리콘 나이트라이드 박막의 굴절률과 lifetime을 유전자 알고리즘과 일반화된 회귀 신경망을 이용하여 모델링하였다. 종래의 모델링에서 평가한 Spread Range 범위보다 더 작은 0.04~1.0 범위에서 평가를 수행하였다. 통계적 실험계획법을 적용해서 수집한 데이터가 이용되었다. 평가결과 보다 낮은 spread range에서 보다 우수한 예측모델이 개발될 수 있음을 확인하였다.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.168-170
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• 2007

Sn-Bi eutectic solder alloy have is good wetting and physical properties. The results of solder paste properties test, melting point is about $139^{\circ}C$ and spread test is represent spread properties of $7{\sim}16%$. The results of shear strength after as reflowed, thermal shock test, high temperature storage test of 500hr and 1000hr at $100^{\circ}C$. The shear strength value range is from 6000 to 11000gf, pull strength value range is from 2200 to 3300gf.

• Fire Protection Technology
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• s.24
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• pp.32-39
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• 1998

A room-corner fire scenario of ISO 9705 with flame spread model developed by Quintiere is applied to the interior finish materials to show the sensitivity of properties derived from AST, E-1321 and ASTM E-1354 is investigated and various range of thermal properties by the author were analyzed in the model. There are including flame heat flux and thermal inertia, lateral flame spread parameter, heat of combustion and effective heat of gasfication. The time for total energy release rate to reach 1MW is examined. Though some areas are neede for improvements, The model appears to predict good results with all the range of input properties and could be

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.242-247
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• 2009

In this paper, we investigate interference between short-range radiocommunication devices (SRDs) with frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-Carlo (MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate (BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than bandwidth does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.299-310
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• 2021

External fire spread has the potential to breach vertical compartmentation and violate the fire safety strategy of a building. The traditional design solution to this has been the use of non-combustible materials and spandrel panels but recent audits show that combustible materials are widespread and included in highly complex systems. Furthermore, most jurisdictions no longer require detailing of spandrel panels under many different circumstances. These buildings require rapid investigation using rational scientific methods to be able to adequately classify the fire risk. In this work, we use an extensive experimental campaign of material-scale data to explore the critical parameters driving upward flame spread. Two criteria are outlined using two different approaches. The first evaluates the time to ignition and the time to burnout to assess the ability for a fire to spread, and can be easily determined using traditional means. The second evaluates the preheated flame length as the critical parameter driving flame spread. A wide range of cladding materials are ranked according to these criteria to show their potential propensity to flame spread. From this, designers can use conservative approaches to perform fire risk assessments for buildings with combustible materials or can be used to aid decision-making. Precise estimates of flame spread rates within complex façade systems are not achievable with the current level of knowledge and will require a substantial amount of work to make progress.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.137-143
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• 2008

In the present study, a forest fire spread was simulated with a three-dimensional, fully-transient, physics-based, computer simulation program. Physics-based fire simulation is based on the governing equations of fluid dynamics, combustion and heat transfer. The focus of the present study is to perform parametric study to simulate fire spread through flat and inclined wildland with vegetative fuels like trees or grass. The fire simulation was performed in the range of the wind speeds and degrees of inclination. From the results, the effect of the various parameters of the forest fire on the fire spread behavior was analyzed for the future use of the simulation in the prediction of fire behavior in the complex terrain.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.217-223
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• 2015

In this paper, the performance of a system was analyzed according to the design parameters of a LED secondary lens that can be applied at a very close range, e.g., for direct lighting or display systems. We designed the secondary lens of the very-close-range LED using an aspheric equation and analyzed its performance-particularly the angle of the beam spread, central luminous intensity, and light uniformity-with respect to the thickness of lens, radius, conic constant, and asphericity (4th). Our analysis shows that four parameters affect the performance. The simulation results indicate an optimal thickness of 1 mm and show that a larger radius yields higher performance. The optimal range for the conic constant was determined as -1.21 to -1.25, the optimal range for the asphericity was determined as 0.0047xx to 0.0049xx (4th).