• 한국음향학회지
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• 제41권2호
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• pp.150-158
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• 2022

본 논문에서는 2021년 9월 동해에서 수행된 초장거리 대역확산 수중음향통신의 해상실험 결과를 제시한다. 8개의 수직 배열 센서를 이용하여 수중음향통신 신호를 수집하였으며, 전송 거리는 160 km로 하였다. 송신 신호로 30 bps의 다중 코드 대역 확산 방식과 100 bps의 처프 대역확산 방식이 사용되었다. 실험 결과 단일 채널에서 채널 부호화 기법이 적용되지 않은 경우에 높은 비트 오류율을 나타내었으나 각 수신 채널에서 프레임 동기화를 수행한 후 신호들에 등이득 조합 다이버시티 기법을 적용하면 비부호화 비트 오류율이 순방향 오류 정정 한계인 0.1 이하로 감소하였다.

• The Korean Journal of Pain
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• 제31권2호
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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.

• 대한방사선치료학회지
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• 제26권2호
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• pp.183-189
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• 2014

목 적 : 조영제는 CT모의치료시 정상조직과 악성종양을 구분하는데 뛰어난 대조도를 제공하기 때문에 CT모의치료에 널리 사용하고 있다. 하지만 조영제는 치료계획 CT에서 일시적으로 존재하기 때문에, 치료계획과 실제 치료 사이에는 Hounsfield Unit(HU)의 차이가 발생하게 된다. 이에 본 연구에서는 조영제 사용으로 인한 HU의 변화가 양성자 치료계획에 미치는 영향을 확인 하고자한다. 대상 및 방법 : 20명의 간암 환자에게서 Phase에 따른 HU값의 변화를 측정하였다, 그리고 5명의 양성자치료계획에서 HU변화에 따른 Range와 Spread-Out Bragg peak(SOBP)의 변화를 살펴보았다. Hand made water phantom을 이용하여 깊이와 HU의 변화에 따른 Range와 SOBP의 변화를 확인하였다. 결 과 : 20명 간암 환자의 HU 변화(Pre contrast, Arterial phase, Porta phase)는 간 조직에서 ($58{\pm}5.7$, $75{\pm}9.5$, $117{\pm}14.6$)이었으며 대동맥에서($40{\pm}6.1$, $279{\pm}49.0$, $154{\pm}22.8$)이었다. 5명의 간암 양성자치료계획에서 HU 변화에 따른 Range 변화는 평균 2.5 mm, SOBP 변화는 평균 1.4 mm 이었다. Hand made water phantom study에서는 HU가 증가함에 따라 Range는 감소되었고 SOBP는 줄어들었다. 결 론 : 양성자 치료계획에서 HU값의 변화는 양성자 Range와 SOBP를 변화시켰다. 실제 양성자 빔에서 HU 변화에 따른 Range와 SOBP의 변화에 대한 추가적인 연구가 필요할 것으로 사료 된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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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.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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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.

• 방재기술
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• 통권24호
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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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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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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.

• 국제초고층학회논문집
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• 제10권4호
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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.

• 설비공학논문집
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• 제20권2호
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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.

• 한국생산제조학회지
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• 제24권2호
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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).