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제주도에 있어서의 풍력에너지 이용을 위한 공학적 예측에 관한 연구(III) : 대정지역에 대하여
고장권,허종철 제주대학교 1986 논문집 Vol.23 No.-
The aim of this paper is to investigate wind speed charateristics based on the wind data of Daejung site as the place of the highest potential energy of wind power in Cheju Island. and to provide optimum design for wind power conversion system being suitable to the wind speed charateristics. The results are as follows 1. Suitable Weibull coefficients, K and C. of wind speed distribution at Daejung site are evaluated. And then the wind speed charateristics are examined and determined. 2. The optimal rated wind speed of which wind power conversion system is suitable to wind speed charateristics is evaluated. 3. Monthly no-generation percentage by the results from calculating optimal starting wind speed and calm is graphed. 4. In the case of varing the system heights from 10m to 70m,optimal rated wind speeds of the system are determined by extrapolating Weibull coefficient, K and C. variations of maximum efficiency and load factor of the system are graphed, depending on the heights.
제주도에서의 풍력에너지 이용을 위한 공학적 예측에 관한 연구(Ⅱ) : 풍력에너지 포텐살에 관하여
고장권,권기린,허종철 제주대학교 1986 논문집 Vol.23 No.-
This paper was designed to compute the actual expected output power of the wind wind energy conversion system in Cheju Island. The wind data were measured by the four local weather stations at Cheju, Seogui. Sungsan and Daejung from Oct. 1984 to Sep. 1985. The ideal wind power density was calculated from which the characteristics of the wind speed at 10m from surface were analyzed. Thus, it made it possible to choose the best site in setting up the wind energy conversion system. We estimated the. optimum rated wind speed of the system to fit with the characteristics of the wind speed of each site.
주유철,이동민,양종태,신병철,임태영,서정균,정기영,최동헌,김원,조영신,고희관 조선대학교 2001 The Medical Journal of Chosun University Vol.26 No.2
Background and Objectives : Palindromic rheumatism (PR) is known to be triggered without any obviously inciting events in most patients, although, in a few cases, attacks have been noted to relate to another events such as weather change, childbirth, ingestion of certain foods, or over-exercise. The aim of this study was to characterize the triggering factors on palindromic attacks. Materials and Methods : We evaluated sixty-four patients with PR for the presence of triggering factors and the relationship between attacks and triggering factors by interview of patients. We considered that there was an probable association between episodes and PR, if episodes within 24 hours prior to PR had triggered at least 50% of all attacks and a definite association between episodes and PR, if episodes within 24 hours prior to PR had triggered 100% of all attacks. Results : In 15 patients (35.9%), there was a possible association between episodes of PR and initiating events. In 8 patients (12.5%), there was a definite association between episodes of PR and initiating events. The triggering factors were physical over-activity including exercise (19/64: 29.7%), foods, such as rawfish, crab, and chicken, including alcohol (19/96: 19.8%). However, there were no difference between the groups with and without the triggering factor in sex ratio, duration and onset of PR, the positive rate of rheumatoid factor and involved sites. Conclusion : Our observations showed that PR was triggered by physical over-activity more than in previous reports and hypersensitivity to foods was a causative factor in some patients with PR. However, patients with triggering factors had a similiar clinical profile to patients without triggering factors.
Prediction of the glass transition temperature of semicrystalline polymer/salt complexes
Koh, Joo Hwan,Park, Jung Tae,Koh, Jong Kwan,Kim, Jong Hak Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of polymer science. Part B, Polymer physic Vol.47 No.8
<P>An explicit expression based on the configurational entropy model, the Flory-Huggins theory and Guggenheim's form of Debye-Hückel theory has been derived for predicting the glass transition temperatures (T<SUB>g</SUB>) of binary semicrystalline polymer/salt complexes. The proposed configurational entropy (S<SUB>c</SUB>) of polymer/salt systems consists of the disorientation entropy of polymer 1 (S<SUB>diso-1</SUB>), the dissociation entropy of salt (S<SUB>diss-2</SUB>), the mixing entropy (S<SUB>mix-12</SUB>) and the specific interaction entropy (S<SUB>spe-12</SUB>). In particular, the effect of crystalline segments was accounted for by the current model. The prediction of the proposed T<SUB>g</SUB> model is in good agreement with experimental data. Our results demonstrate that the small change of the T<SUB>g</SUB> in semicrystalline polymer/salt complexes compared to amorphous systems is mostly attributable to the reduced configurational entropy due to the presence of crystalline segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 793–798, 2009</P>
Koh, Joo Hwan,Seo, Jin Ah,Koh, Jong Kwan,Kim, Jong Hak IOP Pub 2010 Nanotechnology Vol.21 No.35
<P>An amphiphilic graft copolymer of poly(vinyl chloride-<I>graft</I>-4-vinyl pyridine), i.e., PVC-<I>g</I>-P4VP was synthesized via atom transfer radical polymerization (ATRP) and modified by introducing 1,5-dihydroxynaphthalene (DHN) as a hydrogen bonding donor to form hydrogen-bonded macromolecules. The PVC-<I>g</I>-P4VP graft copolymer prepared from a selective solvent for PVC, i.e., tetrahydrofuran (THF) exhibited a well-organized micellar morphology consisting of a P4VP core and a PVC corona. However, the graft copolymer prepared from a good solvent for both domains, i.e., <I>N</I>, <I>N</I>-dimethylformamide (DMF) showed a less-organized, random microphase-separated morphology. Upon the introduction of DHN, a more spherical morphology and a more-organized ‘bicontinuous-like’ morphology was observed in THF and DMF, respectively. This results from strong segregation between the two domains due to the enhanced interfacial energy by DHN. When DHN was removed by methanol, nanoporous films with versatile pore sizes and shapes were generated. </P>
Koh, Joo Hwan,Koh, Jong Kwan,Seo, Jin Ah,Shin, Jong-Shik,Kim, Jong Hak IOP Pub 2011 Nanotechnology Vol.22 No.36
<P>Porous TiO<SUB>2</SUB> nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol–gel process assisted by poly(vinyl chloride-<I>graft</I>-4-vinyl pyridine), PVC-<I>g</I>-P4VP graft copolymer and a ZnO nanorod template. A 7 µm long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO<SUB>2</SUB> sol–gel solution templated by the PVC-<I>g</I>-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO<SUB>2</SUB> nanotubes consisting of 10–15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (<I>M</I><SUB>w</SUB>) and 0.74% for high <I>M</I><SUB>w</SUB> polymer electrolytes. </P>
Preparation and Characterization of Proton Conducting Membranes by Blending PVC-g-PHEA and PVA
Koh, Jong-Kwan,Choi, Jin-Kyu,Seo, Jin-Ah,Zeng, Xiaolei,Kim, Jong-Hak The Membrane Society of Korea 2009 Korean Membrane Journal Vol.11 No.1
This work reports the preparation of proton conductive crosslinked polymer electrolyte membranes by blending poly(vinyl chloride)-g-poly(hydroxyl ethyl acrylate) (PVC-g-PHEA) and poly(vinyl alcohol) (PVA). The PHEA chains of the graft copolymer were crosslinked with PVA using sulfosuccinic acid (SA) via the esterification reaction between -OH of polymer matrix and -COOH of SA. The PVC-g-PHEA graft copolymer was synthesized via atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC backbones. Ion exchange capacity (IEC) continuously increased with increasing concentrations of SA, due to the increasing portion of charged groups in the membrane. However, the water uptake increased up to 20.0 wt% of SA concentration above which it decreased monotonically. The membrane exhibited a maximum proton conductivity of 0.026 S/cm at 20.0 wt% of SA concentration, which is presumably due to competitive effect between the increase of ionic sites and the crosslinking reaction.
Koh, Jong Kwan,Kim, Yong Woo,Ahn, Sung Hoon,Min, Byoung Ryul,Kim, Jong Hak Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of polymer science. Part B, Polymer physic Vol.48 No.2
<P>An amphiphilic comb polymer consisting of poly(vinylidene fluoride-co-chlorotrifluoroethylene) [P(VDF-co-CTFE)] main chains and poly(oxyethylene methacrylate) (POEM) side chains was synthesized using direct initiation of the chlorine atoms in CTFE units through atom transfer radical polymerization, as confirmed by <SUP>1</SUP>H NMR and FTIR spectroscopy. The P(VDF-co-CTFE)-g-POEM comb polymer was introduced as an additive to prepare poly(vinylidene fluoride) antifouling ultrafiltration membranes. As the contents of comb polymer increased, the mechanical properties of membranes slightly decreased due to the decreased crystallinity of the membranes, as revealed by universal testing machine and X-ray diffraction. However, water contact angle measurement and X-ray photoelectron spectroscopy showed that the hydrophilic POEM segments spontaneously segregated on the membrane surfaces. As a result, the antifouling property of the membranes containing P(VDF-co-CTFE)-g-POEM comb polymer was considerably improved with a slight change of water flux. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 183–189, 2010</P>
Koh, Jong Kwan,Kim, Jeonghun,Kim, Byeonggwan,Kim, Jong Hak,Kim, Eunkyoung WILEY‐VCH Verlag 2011 Advanced Materials Vol.23 No.14
<P><B>A solid‐state polymerizable conductive monomer with good conductivity and penetration to the photoelectrode</B> is introduced to iodine‐free, solid‐state dye‐sensitized solar cells (DSSCs) using an easily accessible and widely applicable fabrication method. A conducting polymer as a hole transporting material effectively penetrates into the TiO<SUB>2</SUB> pores and polymerizes with heating to mild temperatures. The fabricated DSSCs exhibited the highest energy conversion efficiency of 5.4% in N719 dye. </P>