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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℃.
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.
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)
김병구(Byung-Gu Kim),여경민(Kyeongmin Yeo),이창훈(Changhoon Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
We investigated modification of near-wall turbulence in the stably stratified turbulent channel flow by using direct numerical simulation. Detailed investigation revealed that the baroclinic torque plays an important role in generation and intensification of small-sized vortical structures. Thus typical length scale of vortical structures becomes smaller under stratification, whereas the length scale associated with temperature variation becomes larger. Both streamwise and spanwise component of baroclinic torque showed strongly intermittent behaviors. In addition to, streamwise baroclinic torque showed that it's non-gaussian behavior returned to like gaussian as stability was increased. As we increased stability, angle of strong vortical structure makes with the horizontal was increased in buffer layer, while decreased in the outer layer.
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.
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.