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송정환,중도장,Song, Jeong-Hwan,Nakajima, Akira 한국재료학회 2007 한국재료학회지 Vol.17 No.11
The static and dynamic hydrophobicities of the water droplets placed on a hydrophobic surface coated using a fluoroalkylsilanes monolayer with different molecular chain lengths were investigated through direct observation of the actual droplet motion during the sliding process. The surface roughness of both was found to be less than 1 nm. The static contact angles of the coated FAS-3 and FAS-17 were respectively $80^{\circ}$ and $108^{\circ}$ at $150^{\circ}C$, 1 h. The slope of sliding acceleration against the water droplet mass exhibited an inflection point, thus suggesting the switching of the dominant sliding mode from slipping to rolling. While their sliding angles were similar in value, notable differences were exhibited in terms of their sliding behavior. This can be understood as being due to the contribution of the shear stress difference at the interface between the solid surface and water during the sliding process. These results show that the sliding acceleration of the water droplets depends strongly on the balance between gravitational and retentive forces on the hydrophobic surface.
저온 동시소결을 위한 Ni-Zn-Cu 폐라이트와 Pb(Fe<sub>1/2</sub>Nb<sub>1/2</sub>)O<sub>3</sub>에서의 열적 거동 및 계면층 특성
송정환,Song, Jeong-Hwan 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.10
In order to apply a complex multilayer chip LC filter, this study has estimated the interfacial reaction and coupling properties of dielectric materials $Pb(Fe_{1/2}Nb_{1/2})O_3$ and Ni-Zn-Cu ferrite materials through low-temperature co-sintering (LTCS). PFN powders were fabricated using double calcinated at $700^{\circ}C$ and then $850^{\circ}C$. While the perovskite phase rate was found to be 91 %, after heat treatment at $900^{\circ}C$ for 6h, the perovskite phase rate and density exhibited a value of 100 % and 7.46$g/cm^3$, respectively. The PFN/Ni-Zn-Cu ferrite, PFN/CUO (or $Pb_2Fe_2O_5$) and ferrite/CuO (or $Pb_2Fe_2O_5$) were mechanically coupled through interfacial reactions after the specimen was co-sintered at $900^{\circ}C$ for 6 h. No intermediate layer exists for the mutual coupling reaction. This result indicates the possibility of low-temperature co-sintering without any interfacial reaction layer for a multilayer chip LC filter.
송정환,이경식,Song, Jeong-Hwan,Lee, Kyung-Shik 대한전자공학회 2000 電子工學會論文誌-SD (Semiconductor and devices) Vol.37 No.7
다양한 수소처리 조건에 의하여 수소 처리된 광섬유에 광섬유 격자를 제작하여, 광섬유 코어 내에 포화된 수소분자 농도와 광섬유 격자의 굴절률 변화폭(photoinduced index modulation)과의 관계를 분석하여 보았다. 실험으로 측정된 광섬유 결자의 굴절률 변화폭은 코어 내에 수소분자 농도가 100ppm 증가함에 따라서 ${\sim}2{\times}10^{-5}$만큼 증가하였다. 그리고 광감도현상에 관여하는 전체결함, 즉 GeE' 센터와 GeH결함은 포화된 수소농도 100ppm 당 대략 $3.8{\times}10^{17}/cm^3$ 만큼 많아지는 것으로 추정된다. The relationship between calculated hydrogen molecular concentration in fiber core and measured index change during the grating growth is analyzed. The index change increases by ${\sim}2{\times}10^{-5}$ per 100ppm of $H_2$ concentration in standard telecommunication optical fiber and the defects related photosensitivity generate ${\sim}3.8{\times}10^{17}$ per 100ppm of $H_2$.
PLD 법에 의한 c-사파이어 기판위의 MnS 박막성장
송정환,Song, Jeong-Hwan 한국재료학회 2007 한국재료학회지 Vol.17 No.9
Pulsed laser deposition was utilized to grow MnS thin films on c-sapphire substrate using a KrF excimer laser at growth temperatures that ranged from room temperature to $700^{\circ}C$. The results of X-ray diffraction (XRD) and UV-visible spectroscopy were employed to investigate the structural and optical properties of the MnS films. While the growth rate decreased as $T_s$ increased, the overall quality of the film improved. The highest quality MnS film was obtained at $700^{\circ}C$. Variations in the $T_s$ resulted in the MnS films exhibiting different growth mechanisms. The oriented (200) rocksalt MnS film was grown at room temperature. In the case of higher $T_s,\;200{\sim}500^{\circ}C$, the films consisted of mixed phases of rocksalt and wurtzite. The main structure of the films was altered to (111) rocksalt when the temperature was increased to in excess of $600^{\circ}C$. This behavior may very well be the result of elements such as surface energy and atomic arrangement during the growth process. The optical band gap of the obtained ${\alpha}-MnS$ film was estimated to be 3.32 eV.
송정환(Jeong Hwan Song),조재훈(Jae Hoon Cho),김채수(Chae Soo Kim) 한국산업경영시스템학회 2006 한국산업경영시스템학회 학술대회 Vol.2006 No.추계
For the steady growth and survival of the enterprise of today, a prompt response to the changes in the competitive market environment is vital. The operational innovations are continuously pursued by the enterprises. The most fundamental method in IT innovation up to today is the SOA(Service Oriented Architecture) which has been accepted as the standard for the system integration and makes the business more flexible. The AHP(Analytic Hierarchy Process) suggested by Saaty in 1971 is a tool to support a decision-making including the personal opinion and intuition, and it is easier than other method. Then, it has an advantage that control the complex object having multiple criteria simply. This study describes the concept and merit of AHP and procedure of AHP. Also this study discusses evaluation procedure of more efficient SOA deployment methodology using AHP. And this study proves through AHP, SOA deployment 6 step using pattern for e-business is more effective and efficient in building the SOA than the method with 12 step to implementing a Service Oriented Architecture, or the method with 4 step from IBM. It shows AHP can be used to evaluate SOA deployment methodology.
산화물계 촉매 적용을 통한 Li-CO₂ 전지 성능개선 연구
송정환(Jeong-hwan Song),서준교(Joon Kyo Seo),마지영(Jiyoung Ma),우중제(Jung-je Woo),송진주(Jinju Song),장일찬(Il Chan Jang) 한국전지학회 2023 한국전지학회지 Vol.3 No.2
Li-CO₂ battery performance is closely related to the formation of reaction products. Li₂CO₃ forms crystals at about 5 nm and MnO₂ is known to have a strong anchoring force with a Li-containing carbonaceous species. In this study, the performance of Li-CO₂ battery was improved by applying a 10wt% mesoporous Beta-MnO₂ catalyst by a hard template method using mesopore silica.