Mastication에 의한 Polystyrene의 機械的分裂

정기현,성좌경,Ki Hyun Chung,Chwa Kyung Sung 대한화학회 1973 대한화학회지 Vol.17 No.4

Roll을 사용한 mastication에 의한 polystyrene(단독시와 rubber와의 blend시)의 기계적 분열에 대하여 검토한 결과는 다음과 같다. 1) Polystyrene 단독시의 기계적 분열속도는 Goto가 밝힌 중합도$(P_t-P_{\infty})$에 관하여 2차인 다음식에 적합함을 알았다. $-\frac{dP_t}{dt} = k_s(P_t-P_{\infty})^2$2 2)Polystyrene-rubber (SBR, BR) blend계에서 polystyrene성분의 분열은 단독시와 비스하게 일어났다. 3)본 실험 조건하에서 polystyrene-rubber (SBR, BR) blend계에서, polystyrene성분의 분열속도도 단독시와 같이 상기한 2차식에 근사적으로 적합됨을 알았다. Following results were obtained for the mechanical degradation of polystyrene (for polystyrene itself and when blended with rubber) by roll mastication. 1) The rate of mechanical degradation for polystyrene itself can be represented by the second-order rate equation proposed by Goto. $-\frac{dP_t}{dt} = k_s(P_t-P_{\infty})^2$ Where Pt is the degree of polymerization of the degraded polymer at t minutes and $P{\infty}$ is the final degree of polymerization. 2) The mechanical degradation of polystyrene component in the polystyrene-rubber (SBR, BR) blend system occurred similarly as that of polystyrene itself. 3) Under the experimental conditions the mechanical degradation rate of the polystyrene component of the polystyrene-rubber, (SBR, BR) blend system followed approximately the same second-order equation as that for polystyrene itself.

경사균열을 갖는 복합재료 보강판의 피로균열 성장에 관한 연구

정기현,양원호,김철,Chung, Ki-Hyun,Yang, Won-Ho,Kim, Cheol 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.12

Fatigue crack growth behavior of inclined cracked Al 6061-T6 thick aluminum plate(6mm) repaired with the bonded composite patch was studied. A 0°inclined crack bonded reinforced composite patch and 15°, 30°, 45°, 60°inclined crack plates were tested. The effect of patch and inclined angle were studied and compared to each other. Also we investigated to the crack propagation direction and debonding behavior during the fatigue crack growth test. In this paper. a study was con(ducted to get an fatigue life, fatigue crack growth ratio and crack growth direction. Finally, the effectiveness of composite patch on inclined cracked plate was investigated. The results demonstrated thats there was a definite variation in fatigue life and fatigue crack growth behavior depending on the inclined crack angle.

전원무결성 해석에 의한 PCB 전원안정화 설계기법 연구

정기현,장영진,정창원,김성권,Chung, Ki-Hyun,Jang, Young-Jin,Jung, Chang-Won,Kim, Seong-Kweon 한국전자통신학회 2014 한국전자통신학회 논문지 Vol.9 No.7

본 논문에서는 전원무결성(Power Source Integrity) 해석을 기반으로 PCB(Printed Circuit Board)내부 전원 선로의 RLC 공진(Resonance)현상을 해석하고 PCB내부 공진현상 감쇄를 위한 설계기법을 제시한다. 제시하는 기법은 PCB의 구조적 특성으로 형성되는 공진주파수를 예측하며, 공진현상 감쇄를 위한 디커플링 캐패시터의 적용위치 및 용량을 결정할 수 있다. 본 논문에서는 산업용 제어기 내부의 메인보드 회로 시뮬레이션 모델을 통해서 PCB 공진현상 감쇄 설계기법에 대한 타당성을 검증하였다. 본 연구결과는 향후, PCB 회로 설계에서 PDN(Power Delivery Network)구조의 안정도 향상에 기여할 것으로 기대된다. This paper introduces the reduction design technique of the resonance phenomenon of the inner PCB based on power integrity from the analysis about the inner power supply line generating RLC resonance. With the technique, the resonant frequency resulted from the structural characteristics of the PCB can be analyzed and allows to predict and the capacitor for resonance phenomenon reduction can be decided as a decoupling capacitor. From the simulation result, it was confirmed that the PCB's resonance phenomenon reduction design technique should have the reduction effect in the inner motherboard of the industrial controller. This research will be contributed to the improvement of the safety of a PDN (Power Delivery Network) structure in the layout design technique of the PCB.

활혈거어법(活血祛瘀法)으로 호전된 중풍환자(中風患者)의 불면(不眠) 2례

정기현,김영석,강경숙,Chung, Ki-Hyun,Kim, Young-Suk,Kang, Kyung-Suk 대한한방내과학회 2002 大韓韓方內科學會誌 Vol.23 No.2

Insomnia is defined as an experience of inadequate or poor-quality sleeping habit, coupled with more than one of the following symptoms : having difficulty sleeping, waking up too early in the morning or not having sound sleep. Insomnia is one of the most common complications that stroke patients experience, which interfere the patients' recovery. The authors observed two improved cases of insomnia in stroke patients by administrating traditional Korean medicine. The patients suffered from insomnia with nocturnal irritation, constipation, petechia of the tongue, thready or weak pulse. These symptoms, were diagnosed as blood stasis and we administered Hyulboochucke-tang three times a day, to improve blood circulation to remove blood stasis. After the administration, nocturnal irritation disappeared and the insomnia improved. Based on this experience, it is considered that enhancing blood circulation to remove blood stasis can be applied to the treatment of insomnia that stroke patients suffer.

Acrylamide와 Styrene의 共重合에 關한 硏究

정기현,Chung, Ki-Hyun 대한화학회 1970 대한화학회지 Vol.14 No.4

1) The copolymerzation of acrylamide $(M_1)$ with styrene $(M_1)$ was studied in absolute methanol solution at $50^{\circ}C$, using azobisisobutyronitrile as a initiator. The monomer reactivity ratios determined at $50^{\circ}C$ were as follows: $r_1=0.2,\;r_2=1.05$ and from these values, Q and e values for acrylamide were calculated as 0.37$(Q_1)$ and 0.45 $(e_1)$. 2) Overall activation energy of copolymer was calculated to 24.3K/cal mol, using the Arrhenius epuation. 3) Measurement of intrinsic viscosity and observation of physical properties were made on the copolymer.

Mastication에 依한 Polystyrene의 機械的 分裂 (第2報). 廢 Polystyrene 樹脂의 再生利用에 關한 基礎的 硏究

정기현,김국중,김상대,Ki-Hyun Chung,Kook Joong Kim,Sang Dae Kim 대한화학회 1975 대한화학회지 Vol.19 No.5

Roll을 사용한 mastication에 의한 polystyrene(단독시와 SBR과의 blend시)의 기계적분열에 대하여 검토한 결과 다음과 같은 결론을 얻었다. 1. Polystyrene-SBR blend계에서 polystyrene 성분의 MWD는, original polystyrene속에 존재하는 고분자량의 polymer 분자가 기계적으로 절단되어 소멸하여 보다 낮은 분자량의 polymer 분자를 생성하며, 분포곡선의 정점은 분열이 진행함에 따라 저분자량역으로 이동하고 점차 높은 정점을 가지는 폭이 좁은 곡선으로 되어 최종적으로 비교적 균일한 polymer로 됨을 실증하였다. 2. Polystyrene chain의 절단수는 roll에 의한 mastication time이 길어짐에 따라 증가하였고, 140, 150 alc $160^{\circ}C$에서 각각 100분간 mastication시킨 처리물에서는 $2.36{\times}10^{20}개,\;1.76{\times}10^{20}개\;및\;1.52{\times}10^{20}$개의 분열 polymer가 생성하였다. 3. Polystyrene의 mechanical degradation의 분열속도는 온도가 상승함에 따라 감소되었고, -8.7kcal/mole이란 부(負)의 활성화에너지를 나타내었으며, 따라서 이 경우의 mechanical degradation은 활성화에너지를 기계적으로 공급받는 화학적 process임을 실증하였다. Polystyrene and polystyrene blended with SBR were subjected to the mechanical degradation by roll mastication. The results obtained are as follows. 1. For the polystyrene which is blended with SBR, the overall shape of the molecular weight distribution curve moves from the higher molecular weight portion to the lower molecular weight portion, becomes narrower in breadth, and its peak becomes higher as the degradation proceeds. The final molecular weight distribution exhibits a relative uniformity. This is due to the fact that only the polymer molecules with the high molecular weight consisted in original polystyrene are degraded mechanically and produced the polymer molecules with the low molecular weight. 2. The scission number of polystyrene chains increases with mastication time, and the number of degraded polymer chains produced when the polymer is masticated for 100 minutes at 140, 150 and $160^{\circ}C$ are $2.36{\times}10^{20},\;1.76{\times}10^{20}\;and\;1.52{\times}10^{20}$, respectively. 3. The rate of the degradation of polystyrene decreases with the mastication temperature. The activation energy is found to have the negative value, -8.7 kcal/mole. Therefore it is indicated that the mechanical degradation is a chemical process of which the activation energy is supplied mechanically.

Global-Navigation Satellite Service를 위한 Electromagnetic Band Gap 구조체 설계

정기현,장영진,여성대,정창원,김성권,Chung, Ki-Hyun,Jang, Young-Jin,Yeo, Sung-Dae,Jung, Chang-Won,Kim, Seong-Kweon 한국전자통신학회 2015 한국전자통신학회 논문지 Vol.10 No.1

본 논문에서는 GNSS(Global-Navigation Satellite Service)에서 사용되는 단말기의 PCB(Printed Circuit Board) 전원안정화를 위해서 PCB 내층에 삽입될 EBG(Electromagnetic Band Gap) 구조체를 제안한다. 버섯모양의 제안된 EBG 구조체를 통한 PCB에서의 관심 금지대역폭/저지대역폭 주파수는 GNSS와 이동통신 관련 주파수를 포함하는 1.55GHz에서 1.81GHz이었으며, 시뮬레이션 결과, 이 구간에서 삽입손실(S21)이 약 -40dB 이하로 형성됨을 볼 수 있었다. 본 연구결과는 향후, PCB 회로 설계의 PDN(Power Delivery Network)구조의 안정화 향상 및 EMI(Electro Magnetic Interference) 대책에 효과적 대응이 유용할 것으로 기대된다. In this paper, a mushroom typed electromagnetic band gap (EBG) structure to be inserted in the printed circuit board (PCB) inner layer in order to stabilize the PCB power line is proposed for global-navigation satellite service (GNSS). In designing the proposed EBG structure, the target stop-bandwidth was designed from 1.55GHz to 1.81GHz including GNSS and mobile communication-related frequency bandwidth. In this bandwidth, the insertion loss(S21) was observed below about -40dB. From the simulation results, it is expected that the stabilization of power delivery network (PDN) structure in the PCB circuit design should be improved and the effective correspondence to EMI will be helpful.

Triton X 系를 乳化劑로 하는 Vinyl Acetate 의 乳化重合

정기현,한상구,Chung, Ki-Hyun,Han, Sang-Ku 대한화학회 1962 대한화학회지 Vol.6 No.1

In the emulsion polymerization of vinyl acetate with Triton-X(Alkyl-aryl-polyether alcohol) and polyvinyl alcohol as emulsifier, some relations between the conditions of polymerization and the polymerization rate, polymerization degree and stability of the emulsion are studied and discussed.

N - Methylolacrylamide 와 Styrene 의 공중합에 미치는 용매 효과

정기현(Ki Hyun Chung),김만호(Man Ho Kim),백태무(Tae Moo Baek) 한국고분자학회 1989 폴리머 Vol.13 No.3

p - 아미노 살리실산과 키틴 , 키토산 혼합물의 용해성에 관한 영향

정기현(Ki Hyun Chung),김경호(Kyoung Ho Kim),김공수(Kong Soo Kim),임정수(Jeong Soo Lim),신재섭(Jae Sup Shin) 한국고분자학회 1988 폴리머 Vol.12 No.1