Mixed Amplitude and Phase Grating Effect in Forced Rayleigh Scattering

Jungmoon Sung,Taihyun Chang,Jo Woong Lee,Hyungsuk Park Korean Chemical Society 1993 Bulletin of the Korean Chemical Society Vol.14 No.1

리튬이온 이차전지용 미세다공성 폴리에틸렌 분리막의 열적 안정성 향상을 위한 내열 고분자층 코팅

성정문(Jungmoon Sung),박준영(Junyoung Park),정현욱(Hyun Wook Jung) 한국고분자학회 2021 폴리머 Vol.45 No.3

에너지 밀도가 높은 리튬이온 이차전지 제조를 위해 폴리올레핀계 분리막에 향상된 열 안정성을 부여하는 것이 매우 중요하다. 이러한 목적을 위해 본 연구에서는 내열성 폴리아미드이미드(PAI) 고분자 용액을 미세다공성 구조의 폴리에틸렌(PE) 분리막에 연속 슬롯 코팅 공정을 적용하여 나노 크기의 박막 코팅 두께로 도포하였다. 적외선 분광 분석(ATR-FTIR)과 전자현미경(SEM) 측정을 통해 미세다공성 막에 PAI의 박막 코팅을 확인하였고, 막 표면과 단면에서 PAI 코팅량과 기공 구조 변화의 관계를 규명하였다. 또한 PAI 코팅 전후 투과도, 기공도, 수축률 등 분리막의 다양한 특성치 변화를 체계적으로 고찰하였다. 이러한 실험 결과를 바탕으로 약 1.23 g/㎡의 PAI 코팅량이 주로 활용된 PE-1 분리막의 내열 특성을 최적으로 향상시킴을 밝혔다. It is very important to impart enhanced thermal stability to polyolefin-based separators for the fabrication of Li-ion secondary batteries with high energy density. For this purpose, in this study, a heat-resistant polyamide-imide (PAI) polymer solution was coated onto a microporous polyethylene (PE) separator with a nano-sized coating thickness, employing a continuous slot coating process. Through attended total reflection infrared spectroscopy (ATR-FTIR) and scanning electron microscope (SEM) measurements, a thin coating of PAI inside the microporous membrane was confirmed, and the relation between the PAI coating amount and the change in pore structures on membrane surface and cross-section was clearly identified. In addition, various characteristics of the separator such as permeability, porosity, and shrinkage before and after PAI coating were systematically investigated. Based on these experimental results, it was found that the PAI coating of 1.23 g/㎡ optimally enhanced the heat resistance properties of the PE-1 separator.

못난이 농산물 활용을 통한 지속가능 식품 서비스 플랫폼 연구

이정문(Jungmoon Lee),이희원(Heewon Lee),윤승현(Seounghyun Yoon),박승민(Seungmin Park) 한국디자인학회 2020 한국디자인학회 학술발표대회 논문집 Vol.2020 No.11

Characterization of Spherical Particles by Light Scattering

Sangwook Park,Jungmoon Sung,Taihyun Chang Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.3

We have studied a characterization method of accurate size of spherical particles by fitting experimental light scattering profile to the rigorous theoretical scattering function. An efficient software has been developed for computation of the theoretical scattering function and regression analysis. A light scattering instrument has been built and the necessary data acquisition and analysis are carried out by use of a personal computer with an emphasis on the reduction of analysis and time aiming that this study will be extended toward a development of a practical particle sizing apparatus. The performance of the instrument and the software has been evaluated with latex spheres and found to be satisfactory.

Self-Powered 30 µW to 10 mW Piezoelectric Energy Harvesting System With 9.09 ms/V Maximum Power Point Tracking Time

Minseob Shim,Jungmoon Kim,Junwon Jeong,Sejin Park,Chulwoo Kim IEEE 2015 IEEE journal of solid-state circuits Vol.50 No.10

<P>A piezoelectric (PE) energy harvesting system with one-cycle maximum power point (MPP) sensing is presented. The one-cycle MPP sensing method uses a very small size sensing capacitor and it can make the transducer output voltage reach the open circuit voltage within one cycle. The proposed MPP sensing block can sense the open circuit voltage with a proposed peak detector and stores the MPP voltage using charge sharing blocks. The one-cycle MPP sensing approach simplifies the design of an MPP tracking algorithm and greatly reduces the tracking time. All control blocks are self-biased and choose the higher voltage between the input or output voltages of the switching converter as a supply voltage (V DD). Therefore, a voltage multiplexer and a low-power ramp generator with V DD independence are also proposed to control the system without additional DC to DC converter. The entire system has been implemented in a 0.35 μm BCDMOS process. It operates at 90 kHz with a 10-mH inductor. The total power dissipation of the controller is 10 μW at a V DD of 2.7 V. The MPP tracking time is only 9.09 ms/V when the input voltage of the switching converter is changed from 3.4 V to 1.2 V.</P>

Probe Diffusion in Polymer Solutions by Forced Rayleigh Scattering

Jaeyung Lee,Taiho Park,Jungmoon Sung,Sangwook Park,Taihyun Chang Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.5

Methyl red diffusion in polymer solutions was studied by a transient holographic method, forced Rayleigh scattering. In semi-dilute solutions of a polystyrene, where no specific interaction with the probe exists, we found within experimental uncertainty that the retardation of diffusion rate of methyl red is independent of the solvents used. This indicates that the hydrodynamic interaction in polymer coils is not affected by the nature of solvents enough to exhibit a detectable change in the diffusion rate of the probe. On the other hand, a substantial reduction of diffusion rate was observed in poly(methyl methacrylate) solutions in toluene. Together with the similar observation reported with poly(vinyl acetate), it is confirmed that hydrogen bond between the probe and the polymer is responsible for the retarded diffusion. The decay-growth-decay profile found in this system reveals a finite difference in diffusion coefficients of cis and trans isomer of methyl red. We estimate the difference and suggest that the cis isomer interacts with the polymer more strongly than the trans isomer.

채널 가감 파장분할다중(WDM)망에서 EDFA 이득의 빠른 과도 응답 제어

박정문,이상헌,신서용,송성호,Park Jungmoon,Lee Sangheon,Shin Seoyong,Song Seongho 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.4A

In this paper, we have shown the gain recovery time of erbium-doped fiber amplifier(EDFA) in WDM add/drop networks can be reduced to less than $3\mu$sec by employing disturbance observer technique with PID controller which is based on 3-level EBFA model. The $3\mu$sec transient time is the fastest one ever reported and it is about $1\%$ of $250\mu$sec previously obtained from disturbance observer technique with PI controller which was based on 2-level EDFA model and it is also less than $200\mu$sec of commercially available EDFAs for WDM networks. We were able to obtain this result by analyzing various system characteristics as we change the parameters of disturbance observer and PID controller. If this result is applied to a commercial product, the product will do an important role in the future dynamic WDM networks. 본 논문에서는 파장분할다중(WDM)망에 적용된 어븀첨가 광섬유증폭기(EBFA)의 이득이 채널의 가감(add/drop)게 따라 변화하는 것을 EDFA의 3-레벨 모델을 기반으로 하는 비례-적분-미분 제어기(PID controller)가 적용된 새로운 외란관측기법을 통해 제어함으로써 이득회복시간을 $3\mu$sec 이하까지 단축시킬 수 있음을 보였다. $3\mu$sec이하의 이득회복 및 안정화 시간은 지금까지 발표된 것들 가운데 가장 빠른 것으로 종전에 2-레벨 EDFA 모델을 기반으로 하는 PI 제어기가 사용된 외란관측기법을 통해 얻었던 $250\mu$sec의 약 $1\%$, 그리고 현재 상용화되어 있는 WDM 망용 EDFA의 가장 빠른 이득회복시간인 $200\mu$sec의 $2\%$도 채 안되는 시간이다. 이러한 결과는 외란관측기의 파라미터와 PI 제어기의 제어 파라미터의 변화에 따른 시스템의 특성 변화를 분석하여 제어기를 최적함으로써 얻어 낼 수 있었으며, 이를 상용화에 적용할 경우, 향후 유동적(dynamic) WDM 망에서 매우 중요한 역할을 할 것으로 전망된다.

조향계의 중간축어셈블리 형식 및 조건에 따른 조향 감성품질평가

구광모(Kwangmo Koo),이종화(Jonghwa lee),김정문(Jungmoon kim),박종남(Jongnam park) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

Emotional Quality Criteria of steering system in vehicle is more important and required from customer. Intermediate Shaft Assembly is not only simple design and also, easily mounting to the vehicle. Therefore, purpose of this study is to improve the product engineering of Intermediate shaft assembly by evaluated and analyzed the related quality factors with each type of Intermediate shaft. This study is verified the 5types of Intermediate shaft assembly with following items; noise, torsional stiffness, FFT analysis and emotional quality with looseness grade in bench and vehicle. The results are followings; First, vibration value is small when sti ffness is high in bench and vehicle. Especially, ball-slider type is best stiffness and quality. Second, Vibration value is small when an gle variation is small with lash. For example, Vibration value is increased with minimum lash for 23’and emotional level is evaluate d for 6+.In conclusion, to meet the emotional level for 7-, accepted lash criteria of Intermediate shaft assembly may be considered the maximum lash for 14’ under the loaded the torque for 4N.m when tested.