경사진 QRD를 이용한 전자파 잔향실 내 전자기장 균일도 향상을 위한 연구

이병준,김혜광,이중근,Lee, Byoung-Jun,Kim, Hye-Kwang,Rhee, Joong-Geun 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.6

Schroeder 방식의 QRD(quadratic Residue Diffuser) 구조에서 더욱 진화한 경사진 QRD를 사용하여 전자파 잔향실(reverberation chamber) 내의 전자기장 균일도를 향상시켰다. FDTD(Finite-Difference Time-Domain) 수치 해석방식을 이용하여 $2{\sim}3GHz$ 대역에서의 전자파 잔향실 내의 전자기장의 분포를 해석하였다. QRD 경사 각도의 조절과 경사 방향을 전환하여 전자파 잔향실 내부의 시험 공간에서의 E_x,\;E_y,\;E_z$ 샘플의 표준편차 및 공차가 각각 0.3 dB, 2.5 dB 향상되고 전체적으로 전자기장 분포의 균일성이 확보되었다. The field uniformity inside the reverberation chamber has been improved using sets of quadratic residue diffuser (QRD). The electromagnetic field inside the reverberation chamber with the dimension of $100{\times}80{\times}80cm$ has been analyzed by the finite-difference time-domain(FDTD) method. The calculated fields in a $40{\times}30{\times}30cm$ test volume have been sampled to obtain a standard deviation and field uniformity. Results show that the standard deviation of the calculated field and uniformity have been improved by varying angles and orientation of the inclined surfaces of the QRDs installed inside the reverberation chamber.

알루미늄 AC4CH 합금주물의 냉각속도 변화에 따른 기계적 물성 예측 및 전산모사 적용

이병준,조인성,Lee, Byoung-Jun,Cho, In-Sung 한국주조공학회 2018 한국주조공학회지 Vol.38 No.2

In a numerical study, equations relating the mechanical properties and cooling rate in a casting process have been applied to an AC4CH cast aluminum alloy. Good agreement was found between the measured and predicted material properties. Step-shaped steel blocks were made to comprise a casting mold with a Y-shaped cavity. Thermometers were inserted into each step of the mold to investigate temperature changes. The microstructure and mechanical properties, such as hardness and tensile stress were measured for each cut of piece. The correlation between the cooling rate and SDAS was found by curved fitting. Moreover, both the solidification time and the temperature were simulated using a commercial package, ZCast. The simulation results for yield strength, tensile strength, elongation, and hardness were compared with experimental results. Using the estimated K and n values, the hardness values of a ship propeller were simulated, and the results were similar to those obtained for actual castings.

와이브로 시스템의 채널 대역폭 확장에 따른 인접채널 간섭 분석

이병준(Byoung Jun LEE),김진우(Jin Woo Kim),곽도영(Do Young Kwak),강충구(Chung G. Kang) 한국통신학회 2010 한국통신학회 학술대회논문집 Vol.2010 No.2

체육수업 팀 활동에서 분노의 유발원인 분석

이병준(Byoung Jun Lee),이주욱(Joo Wook Yi),김동환(Dong Hwan Kim) 한국스포츠교육학회 2009 한국스포츠교육학회지 Vol.16 No.3

물 함량과 NCO Index 변화가 자동차용 폴리우레탄 시트 폼 패드의 정적 안락감에 미치는 영향 고찰

이병준 ( Byoung Jun Lee ),이성훈 ( Sung Hoon Lee ),최권용 ( Kwon Yong Choi ),김상범 ( Sang-bum Kim ) 한국공업화학회 2017 공업화학 Vol.28 No.1

본 연구에서는 다양한 NCO index에서 물 함량 변화가 자동차용 폴리우레탄 시트 폼 패드의 정적 안락감에 미치는 영향을 알아보았다. 정적 안락감에 영향을 미치는 요인을 파악하기 위해 UTM을 사용한 정하중 특성 시험을 통하여 히스테리시스 곡선을 나타냈으며, 이를 통해 25% 변형 시 경도와 65% 변형 시 경도, hysteresis loop area, hysteresis loss (%), 그리고 Sag factor를 구하였다. 동일한 NCO index에서 물 함량이 증가함에 따라 우레아 결합의 증가로 경도가 증가하고, 가교밀도가 증가하는 경향을 swelling ratio 측정으로 확인하였으며, 이에 따라 복원력은 감소하는 경향을 확인하였다. 또한 표면 경도의 증가로 인해 Sag factor가 감소하는 경향을 확인하였다. 동일한 물 함량에서 NCO index가 증가함에 따라 우레탄과 우레아 결합이 이소시아네이트와 추가 반응하여 가교도와 경도가 증가하고 이에 따라 복원력이 감소함을 확인하였다. In this study, we identified how the water content change in various NCO index affects the static comfort of polyurethane seat foam pad for automobiles. In order to identify factors that affect the static comfort, a static load test was performed using UTM to plot a hysteresis curve. The hardness of the foam when it was modified by 25, 65%, hysteresis loop area, hysteresis loss (%), and Sag factor were also obtained. By measuring the swelling ratio, it was confirmed that, as the water content increased in a fixed NCO index, the hardness and crosslinking density increased while the restoring force decreased due to the increase of urea bond. Also the Sag factor decreased due to the increase of surface hardness. As the NCO index increased in a fixed water content, the urethane and urea bond reacted more with isocyanate, leading to an increase in hardness and decrease in restoring force.

극한 환경용 소재 초저온용 고분자 재료 기술 현황

이병준 ( Byoung Jun Lee ),김상범 ( Sang Bum Kim ) 한국공업화학회 2014 공업화학전망 Vol.17 No.5

산업의 발전으로 초저온 상태에서 안정한 고분자 복합재료들의 중요성이 대두되고 있다. 초저온 상태의 고분자 복합재료는 우주왕복선 등의 소재로 쓰이고 있으며, LNG운반선에서 폴리우레탄 폼 보냉제의 성능이 운반선의 성능을 결정짓는 중요 요소가 되고 있으며 이에 따른 안정성도 중요시되고 있다. 이에 따라 저온 환경 하에서의 적합한 재료 평가 및 시험법이 개발되고 있다. 또한 초저온 환경에서 안정한 고분자 복합 재료 기술개발을 위해서 저온 및 초저온 환경에 뛰어난 기계적 특성을 가지는 구조용 재료의 개발이 절실히 요구되어 지고 있다. 그에 따른 열전도도, 전기 전도도 및 열팽창 계수 등 응용 분야에 따른 기계적 물성 이외의 재료로서 요구 사항을 만족시켜야 한다. 본고에서는 초저온용 보냉재로 사용되는 폴리우레탄의 상온과 초저온 거동특성과 초저온 범위에서 구조물의 신뢰성을 얻기 위해서 재료의 파괴 인성, 피로 거동 및 균열 진전 등 특성을 개괄적으로 정리하였다. 그리고 초저온용 고분자 복합재료로서 사용되는 수지의 유리전이온도(Tg)와 물성 측정을 통해서 초저온용 재료로서 적합한지를 판단하였다.

호흡기 내과계 중환자실 전공의 수와 중환자실 사망률의 관련성

이병준 ( Byoung Jun Lee ),이창훈 ( Chang Hoon Lee ),김덕겸 ( Deog Kyeom Kim ),김경희 ( Kyoung Hee Kim ),김은선 ( Eun Sun Kim ),박태연 ( Tae Yun Park ),정근범 ( Keun Bum Chung ),강효재 ( Hyo Jae Kang ),정윤정 ( Yun Jeong Jeong ) 대한내과학회 2010 대한내과학회지 Vol.79 No.2

Background/Aims: The treatment outcome of patients hospitalized in intensive care units (ICUs) can be influenced by physician factors, including both intensivists and resident physicians. We evaluated the association between the number of residents who are exclusively responsible for the ICU and the mortality rate in a medical ICU. Methods: The data obtained from an open medical ICU in a teaching hospital from Jan. 2005 to Dec. 2009 were analyzed retrospectively. We evaluated the associations between the ICU mortality rate and both the number of resident physicians and the number of patient-days per resident physician using multivariate Poisson regression analysis adjusted for year and month. Results: The months with fewer than two residents tended to have a higher ICU mortality rate, although this difference was not significant in the univariate analyses. Multivariate Poisson regression analysis showed that months with fewer than two residents had a significantly higher ICU mortality rate compared with months with two residents (incidence risk ratio (IRR) 1.59, 95% confidence interval (CI) 1.05-2.41; p=0.029). The number of ICU patient-days per resident physician was not associated with the ICU mortality rate (IRR; 1.00, 95% CI, 0.99-1.01; p=0.649). Conclusions: The presence of fewer than two residents exclusively responsible for the medical ICU was an independent risk factor of a higher ICU mortality rate. However, no association was found between the number of ICU patient-days per resident physician and the ICU mortality rate. (Korean J Med 79:155-162, 2010)

대학가 주변 PC방의 실내 금연법 시행에 따른 PM2.5 농도 평가

이병준 ( Byoung Jun Lee ),이현수 ( Hyun Soo Lee ),이석용 ( Seok Yong Lee ),허정 ( Jung Heo ),정다영 ( Da Young Jung ),권제혁 ( Je Hyeok Gwon ),김건영 ( Keon Young Kim ),심재윤 ( Jae Yoon Shim ),이근창 ( Geun Chang Lee ),양원호 ( 대구가톨릭대학교 자연과학연구소 2014 자연과학연구논문집 Vol.12 No.1

As the National Health Promotion Act was again revised, expanding the coverage of non- smoking areas to include restaurants and Internet Cafe, as well as entertainment venues such as bars and pubs, the purpose of this study was to determine the change in PM2.5 concentrations before and after non-smoking policy was enforced and to evaluate the status of the non-smoking policy on its own. PM2.5 Concentration levels were measured on Internet Cafes (n=12) in Hayangsi using fine-particle direct monitor, from December in 2013 through February in 2014. For accurate measurement of the concentration of PM25, researchers investigated the environmental impacts of each factor in Internet Cafe (block form between Internet Cafe and smoking room, the number of cigarettes and users observed). Measured PM2.5 concentration data were processed and analyzed. When non-smoking policy is not enforced the average indoor and outdoor PM2.5 concentrations were found to be 90.89±64.92 μg/m3 and 26.69±14.51 μg/m3 respectively, otherwise when non-smoking policy is enforced, the average indoor and outdoor PM2.5 concentrations were 77.90±53.67 μg/m3 and 44.77±23.77 μg/m3. Though we found that concentrations were numerically lower than before, the concentration of post results showed no significant difference compared to the previous results.

파상풍 환자의 치험례

이병준(Byoung Jun Lee),류종회(Chong Hoy Ryu),설인택(In Taek Seol),김영균(Young Kyun Kim),김수관(Su Kwan Kim) 대한구강악안면외과학회 1993 대한구강악안면외과학회지 Vol.19 No.2

Tetanus is a disorder of neurotransmission associated with infection by Clostridium tetani, and is characterized by convulsive spasm. The organisms produce the exotoxin tetanospasmin which involves the neuromuscular organs. Most of tetanus are caused by wounds, but in some of cases, portal of entry may not be obvious. History and clinical findings suggest the diagnosis. The most therapeutic maneuver is to insure airway patency, other therapeutic principles include antimicrobial drugs, active and passive immunization and supportive care. A 51-year-old woman with moth opening limitation and dysphagia visited our hospital. We had diagnosed her as tetanus and treated successfully.

새로운 인계 난연제 합성과 이를 이용한 경질 폴리우레탄 폼의 난연성 및 물성 분석

이병준 ( Byoung Jun Lee ),김상범 ( Sang Bum Kim ) 한국공업화학회 2016 공업화학 Vol.27 No.6

본 연구에서는 새로운 비할로겐-인계 난연제를 포함하는 경질 폴리우레탄 폼[BHP-RPUF]과 할로겐-인계 난연제를 포함하는 경질 폴리우레탄 폼[TCPP-RPUF] 그리고 난연제를 포함하고 있지 않은 폴리우레탄 폼[Pure-RPUF]의 기계적물성 및 난연 특성에 대해 비교 분석하였다. 새로운 비할로겐-인계 난연제인 bis(3-(3-hydroxypropoxy)propyl) phenyl phosphate [BHP]는 disodium phenyl phosphate와 3-chloro-1-propanol의 반응을 통해 합성하였다. BHP-RPUF, TCPP-RPUF, 그리고 Pure-RPUF의 압축강도는 BHP-RPUF와 TCPP-RPUF가 비슷한 압축강도를 나타내었고, 열전도도에서는 BHPRPUF가 TCPP-RPUF보다 낮은 값인 0.023 W/m·K를 갖는 것을 확인하였다. 반응속도와 SEM을 통해 기공의 크기를 측정하여 열전도도에 미치는 영향에 대하여 분석하였고, TGA 분석을 통해 내열성을 확인하였다. 난연성은 한계산소지수(Limited Oxygen Index) 측정 실험을 통하여, Pure-RPUF보다 BHP-RPUF에서 난연성이 향상됨을 확인하였다. In this study, we compared and analyzed the flame retardancy and mechanical properties of three different rigid polyurethane foams (RPUF) containing noble non-halogen phosphorus flame retardant (BHP-RPUF) or halogen-phosphorus flame retardant (TCPP-RPUF) or no flame retardant material (Pure-RPUF). The noble phosphorus-based flame retardant, bis(3-(3-hydrox-ypropoxy) propyl) phenyl phosphate (BHP), was synthesized by the reaction between disodium phenyl phosphate and 3-chloro-1-propanol. Through universal testing machine (UTM) experiments, the compressive strength of BHP-RPUF was sim-ilar to that of TCPP-RPUF. From the result of foam morphology analysis, it was confirmed that BHP-RPUF has the lowest thermal conductivity of 0.023W/m·K. We also measured the size of air bubbles using reaction velocity and SEM, and ana-lyzed how they affect the thermal conductivity. In addition, the heat-resisting property was investigated through TGA analysis. The limited oxygen index (LOI) test confirmed that BHP had the ability to increase the flame retardancy of RPUF.