새로운 Poly ( enaryloxynitriles ) 의 합성과 그 열적 성질

김병구,배장순,공명선 ( Byung Gu Kim,Jang Soon Bae,Myoung Seon Gong ) 한국공업화학회 1995 공업화학 Vol.6 No.4

주쇄에 다양한 화학 구조를 가진 새로운 poly(enaryloxynitriles)을 p-bis(1-chloro-2,2-dicyanovinyl)benzene (2)과 sulfide, sulfone, azo, acetal, imide, ether 그리고 ester 결합을 포함한 디 페놀 유도체의 나트륨 염과 계면중합에 의하여 합성하였다. 생성된 중합체는 고유 점도가 0.12∼0.45 dL/g이었으며 중량 평균 분자량은 9000∼12000이었다. 그들 중합체는 극성 반양자성 용매에 매우 잘 녹았으며 alkyl, acetal, ester를 가진 diphenol로부터 합성된 중합체는 THF나 aceton에도 매우 잘 녹았다. 그러나 중합체의 DMF 용액으로 부터 용매 증발후 단단하고 부서지시 쉬운 막이 형성되었다. 중합체들은 350℃에서 열경화 반응이 진행되어 불용성 물질이 형성되었다. 거의 모든 중합체가 350∼450℃사이에서 10% 중량 감량을 유지하였으며, 500℃에서 잔사량은 70∼85%로서 열안정성을 보여주었다. New poly(enaryloxynitriles) with a variety of chemical structure in the main chain were prepared by interfacial polymerization of p-bis(1-chloro-2,2-dicyanovinyl) benzene (2) with disodium salts of diphenol derivatives containing sulfide, sulfone, azo, acetal, imide, ether and ester group. The resulting polymers possess inherent viscosities of 0.12∼0.45 dL/g and Mw in the range 9000∼12000. They are easily soluble in polar aprotic solvents. The polymers derived from diphenols with alkyl, acetal and ester units were even soluble in common organic solvents such as THF and acetone. Brittle and hard films can be cast from DMF solutions. These polymers show a large exotherm in differnetial scanning calorimetry and undergo a curing reaction around 350℃ to form insoluble materials. Almost all the poly (enaryloxynitriles) retained a 10% weight loss being recorded between 350∼450℃ in nitrogen and displayed 70∼85% residual weight at 500℃.

평균풍속 및 난류 예측을 위한 도심지 모델

김병구(Byung-Gu Kim),이창훈(Changhoon Lee),김석철(Seogcheol Kim),주석준(Seok-Jun Joo),장동두(Dong Du Jang),심우섭(Woo-Sup Shim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

The study of model for velocity and turbulence within the urban canopy was carried out. To evaluate existing urban model we conducted wind tunnel experiment and large-eddy simulation (LES). Mean velocity profile and turbulence are measured within simple three different obstacle arrays. To obtain supplemental data and to verify morphological model large-eddy simulation was performed. Several methods have been used to achieve embodying the flow field in urban area. Recently, morphological method obtaining flow parameters from the statistical or physical representation of obstacle elements is a arising method. It was found that all morphological model, evaluated in this study, over predict the friction velocity, most sensitive one among the flow parameters. Velocity and turbulence in the urban canopy layer were improved by the correction using 'true' friction velocity.

복잡한 지형을 지나는 도시경계층유동의 Large-eddy Simulation

김병구(Byung-Gu Kim),이창훈(Changhoon Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

Boundary-layer flows over arrays of regularly distributed obstacles with various wind directions were investigated by wind-tunnel experiment and large eddy simulation. Inflow conditions are generated such that given profiles of mean wind and turbulence properties such as integral length or time scales are matched. Constant Smagorinsky subgrid-scale model is used. Surface flow parameters such as friction velocity, roughness length and displacement thickness were evaluated by changing wind direction. It was found that the parameters for the arrays composed of slender rectangular cylinders whose characteristics are similar to a real urban area than cube arrays are highly sensitive to the wind direction. Many previous works that have been focused on cube arrays would differ from the real urban area in the characteristics of flow field.

안정 성층인 채널유동에서 난류의 감쇠

김병구(Byung-Gu Kim),이창훈(Changhoon Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Suppression of turbulence in stably stratified flow is investigated in this study using large eddy simulation. Stably stratified turbulent flow owing to negative buoyancy or adverse density gradient is important phenomenon that is frequently observed in geophysical flow as well as in engineering flow. Severe suppression of turbulence or relaminarization was reported from many experiments but it was not reproduced by using numerical simulation typically performed for not only low Richardson number but also low Reynolds number flow. In this study, near-wall behavior of suppression of turbulence in stably stratified channel flow was investigated in both wide range of Richardson number and Reynolds number. To accomplish sufficiently high Reynolds number flow and to diminish a numerical error, large eddy simulation employing spectral method is conducted.

창호 결로 성능의 물리적 분석과 컴퓨터 시뮬레이션 분석에 대한 비교 연구

김병구(Kim, Byung-Gu),고귀한(Koh, Gwi-Han),홍승훈(Hong, Seung-Hun) 대한건축학회 2014 대한건축학회 학술발표대회 논문집 Vol.34 No.2

고밀도 가스 확산 예측을 위한 라그랑지안 확산 모델

김병구(Byung-Gu Kim),이창훈(Changhoon Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8

분자선에피택시에 의해 성장한 ZnO 나노결정 박막에 완충층 두께와 활성층 성장 온도가 미치는 효과

김병구 ( Byung Gu Kim ),남기웅 ( Gi Woong Nam ),박영빈 ( Young Bin Park ),박형길 ( Hyung Gil Park ),임재영 ( Jae Young Leem ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.9

ZnO thin films were deposited on a Si (100) substrate by plasma-assisted molecular beam epitaxy (PA-MBE). Growth of ZnO thin films on a Si substrate is limited due to the large difference between the lattice constants of ZnO and Si. In this research, we studied the effects of the buffer-layer thickness and active-layer growth temperature on the structural and optical properties of ZnO thin films. Scanning electron microscopy, X-ray diffraction, and photoluminescence were carried out to investigate the structural and optical properties of the ZnO thin films. The structural and optical properties of the ZnO thin films were improved when the buffer layers were grown for 20 min and the active layers were grown at 800 ℃.(Received September 9, 2013)

경찰공무원의 근무환경이 재난대응역량에 미치는 영향

김병구 ( Kim¸ Byung Gu ),이상훈 ( Lee¸ Sang Hun ) 한국경찰학회 2021 한국경찰학회보 Vol.23 No.5

재난 상황에서 위기관리 국가의 시스템이 제대로 작동하느냐는 물음에 우리 사회의 우려가 커지고 있다. 경찰은 전통적으로 법집행, 범죄예방 및 대응, 그리고 치안서비스를 제공하는 역할을 담당하며 이러한 본연의 역할 이외에 국가적 재난 및 위기사태 시 지원기관으로서 국가 및 지자체 등을 지원하는 역할도 동시에 담당해야 한다. 이러한 경찰관의 재난 대응 능력은 근무환경의 개선으로 인해 증대 될 수 있을 것이며 이를 실증적 분석을 통해 알아보고자 한다. 이를 실증적으로 검증 위하여 경찰청 및 전국의 시ㆍ도경찰청, 경찰서 그리고 지구대와 파출소에 근무하는 경찰공무원을 대상으로 설문조사를 실시하였으며 최종적으로 1,242매가 회수되었다. 연구 결과, 경찰관들의 경찰관의 근무환경은 그들의 재난 대응 능력에 통계적으로 유의미한 정적 (+) 영향을 미치는 것으로 나타났다. 이 연구를 통하여 경찰관들의 재난대응과 관련 있는 요인을 찾아내고 이를 향상시킬 수 있는 구체적인 개선방안을 제시해 후속 연구 활성화 기반을 마련하고자 한다. Concerns in our society are growing when asked if the crisis management state’s system is working properly in a disaster situation. The police traditionally play a role in law enforcement, crime prevention and response, and providing security services, and should also play a role in supporting the state and local governments as a support organization in the event of a national disaster and crisis. This police officer's ability to respond to disasters can be increased due to the improvement of the working environment, and this will be investigated through empirical analysis. To this end, a survey was conducted on the National Police Agency, metropolitan and provincial police offices, police stations, and police officials working in patrol stations and police boxes across the country, and 1,242 copies were finally recovered. As a result of the study, it was found that the working environment of police officers had a statistically significant positive (+) effect on their ability to respond to disasters. Through this study, it is hoped that police officers will evaluate their ability to respond to disasters and present specific improvement measures to lay the foundation for revitalizing follow up research.

경찰협상팀 운용현황과 발전 방안에 대한 연구

김병구 ( Byung Gu Kim ) 대한범죄학회 2010 한국범죄학 Vol.4 No.2

There have been several crisis situations that hostages and even policemen were killed or injured during tactical team``s entry. But since 1970``s the foreign law enforcement agencies have developed crisis negotiation skills and actively used trained negotiators. They are dispatching negotiators to domestic and suicide situations as well as hostage incident cases. In using flexible tactics through crisis intervention such as active listening, they saved many people in crisis situations. Crisis negotiation skills have consistently been proven to be law enforcements`` effective strategies to resolve crisis incidents during last 30 years. As the community is more and more complicate, we can no longer rely on informal control functions of family or community. This paper intended to examine theoretical concept of crisis negotiation, to review the current stage of our police policies in this area, and to offer some helpful suggestions for further developing our capabilities of crisis negotiation tactics. Since it is expected that threats of suicide, hostage, and psychiatric disorder crisis will increase continuously, our law enforcement agencies should develop and maintain negotiation capabilities. This may include establishing management policies for negotiation teams, conducting intensive training for negotiation, and organizing a multi-agency ``negotiation cadre center`` in the KNP.

도시지형을 지나는 난류 경계층 유동의 대와류 수치모사

김병구(Byung-Gu Kim),이창훈(Changhoon Lee) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5

Large-eddy simulation has been conducted to simulate turbulent boundary-layer flows over an array of regularly distributed obstacles considering various cases of a wind incident angle. The effect of wind direction was investigated in the square cube array that periodic boundary condition was imposed. Characteristics of the turbulent flow over the obstacle array have been found to be very sensitive to the direction of prevailing wind or of mean wind or of mean pressure gradient. Velocity of planar average shows that the direction of the velocity is not always aligned with mean pressure gradient but varied with height, specially below the urban canopy. Turbulent statistics are changed sensitively with the direction of mean pressure gradient around 10 degree.