양이온 교환막을 이용한 이산화탄소의 전기화학적 환원

김학윤,안상현,황승준,유성종,한종희,김지현,김수길,장종현,Kim, Hak-Yoon,Ahn, Sang Hyun,Hwang, Seung Jun,Yoo, Sung Jong,Han, Jonghee,Kim, Jihyun,Kim, Soo-Kil,Jang, Jong Hyun 한국전기화학회 2012 한국전기화학회지 Vol.15 No.4

전기화학적 환원을 통한 이산화탄소의 활용을 위한 노력은 오래 전부터 계속되어 왔다. 최근에는 액체연료 중 가격이 비싸고 그 활용도가 높은 포름산의 생성을 위한 연구가 많이 진행되고 있지만 실제 포름산을 생성하고 분석하는 과정에서 효율의 개선과 분석에 어려움이 따른다. 따라서 이산화탄소 환원을 이용한 포름산 생성에 필요한 시스템의 제조, 반응 조건의 개발 및 분석 방법의 정량화가 필요하다. 본 연구에서는 이산화탄소의 전기화학적 환원을 통한 포름산의 생성을 진행하고 생성된 포름산의 양을 분석하였다. 실험에 이용된 셀은 양이온 교환막을 사용하는 대용량의 회분형 셀을 이용하였으며 전위차계를 통하여 삼전극에서 전기화학 실험을 진행하였다. 전기화학 실험은 다양한 촉매 금속을 이용하여 선형 전위 주사법과 chronoamperometry를 통해 진행했으며 이 때 기준전극은 염화은 전극을 이용하였고 상대전극은 백금 전극을 사용하였다. 실험을 통해 생성된 포름산의 농도를 high performance liquid chromatography(HPLC)를 통하여 분석하여 시스템의 적정성과 분석 방법의 유효성을 검증하였다. Electrochemical reduction of carbon dioxide has been widely studied by many scientists and researchers. Recently, the production of formic acid, which is expensive but highly useful liquid material, is receiving a great attention. However, difficulties in the electrochemical reduction process and analyzing methods impede the researches. Therefore, it is important to design an adequate system, develop the reduction process and establish the analyzing methods for carbon dioxide reduction to formic acid. In this study, the production of formic acid through electrochemical reduction of carbon dioxide was performed and concentration of the product has been analyzed. Large scale batch cell with proton exchange membrane was used in the experiment. The electrochemical experiment has been performed using a series of metal catalysts. Linear sweep voltammetry (LSV) and chronoamperometry were performed for carbon dioxide reduction and electrochemical analysis using silver chloride and platinum electrode as a reference electrode and counter electrode, respectively. The concentration of formic acid generated from the reduction was monitored using high performance liquid chromatography (HPLC). The results validate the appropriateness and effectiveness of the designed system and analyzing tool.

피로 하중을 받는 열간 압연 연강판재의 기계적 성질과 모우드 변화에 관한 연구

김학윤,이성호 ( Hak Yoon Kim,Seong Ho Lee ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.4

Using natural frequency measurement method, which is one of NDT method, natural frequency of the hot-rolled mild steel plate(specimen) under fatigue loading was measured. Between the degradation of the specimen under fatigue loading and the variation of the natural frequency of the specimen was investigated. As a result, the degradation of the specimen was described and monitored as variation of natural frequency of specimen. The natural frequency of specimen decreased gradually under fatigue loading. This means the variation of material properties of specimen. Especially. It means the variation of Young`s modulus of specimen.

UV-B가 강낭콩(Phaseolus vulgaris L.)의 지방산 구성, 지질과산화 및 polyamine 함량에 미치는 영향

김학윤,Kim Hak-Yoon 한국생명과학회 2006 생명과학회지 Vol.16 No.3

To investigate the effects of UV-B on fatty acid composition, lipid peroxidation and biochemical defense responses of plant, kidney bean (Phaseolus vulgaris L.) was subjected to enhanced UV-B irradiation [daily dose : 0.02.(No UV-B) and 11.36 (enhanced UV-B) $kJ\;m^{-2};UV-B_{BE}$] for 3 weeks. UV-B drastically inhibited both height and dry weight of kidney bean. The content of malondialdehyde significantly increased by about 50% after 3 weeks of UV-B irradiation. The ratio of unsaturated to saturated fatty acids of kidney bean was increased by UV-B irradiation. Three major polyamines of kidney bean leaves : putrescine, spermidine and spermine, were observed. All of the polyamine contents were increased with UV-B irradiation. These results suggested that enhanced UV-B radiation caused oxidative stress on lipids and biochemical protection responses might be activated to prevent from damaging effects of oxidative stress generated by UV-B irradiation. UV-B에 의한 강낭콩 식물의 피해양상, 지질과산화, 지질조성 변화와 UV-B에 대한 식물의 방어기작 등을 조사하기 위하여 3주간 UV-B 조사 실험을 수행하였다. UV-B 처리에 의해 초장이 약 22% 정도 감소하는 것으로 나타났다. MDA 함량은 UV-B 처리에 의해 약 50% 정도 증가하는 것으로 나타났다. Glutathione 및 ascorbate acid 함량은 UV-B 조사에 의해 산화형이 증가하고 환원형이 감소하는 것으로 나타났다. UV-B 조사에 의한 지방산 구성 변화를 조사한 결과 당지질 및 인지질 모두 UV-B조사에 의해 포화지방산이 증가하는 것에 반해, 불포화지방산이 감소하는 것으로 나타났다. 강낭콩 잎에는 주로 3종류의 polyamine이 존재하는 것으로 나타났으며, 3종류 모두 UV-B 조사에 의해 증가하는 것으로 나타났다. 본 실험 결과로 볼 때, UV-B 조사는 활성산소를 생성하여 생체막 지질에 직접적인 영향을 미치는 것으로 나타났으며, ascorbate acid, glutathione, polyamine 등의 항산화물질들이 이에 대한 피해를 최소화하기 위하여 작용하는 것으로 나타났다.

고성능 회전익기의 개발동향과 자동회전의 해석기법

김학윤,신병준,Kim, Hak-Yoon,Sheen, Byung-jun 한국항공운항학회 2014 한국항공운항학회지 Vol.22 No.3

Technical history of VTOL aircraft is examined from the early helicopter appearance to recent experimental rotorcraft in order to distinguish the core issues of those aircraft. Performance and technological challenges of some VTOL aircraft such as tilt rotor, convertiplane, gyroplane, and coaxial helicopter are discussed. As a new generation high performance rotorcraft, Sikorsky X2 is intensively investigated. Considering the developmental history of X2, the autorotational ability at high speed is recognized as a core technology. Analytic method of autorotation and some results are shown and presents research subjects related to the future Korean high performance rotorcraft.

봉선화(Impatiens balsamina L.)에 대한 pH 수준별 처리가 항산화 물질 및 관련 효소 활성에 미치는 영향

김학윤,Kim Hak Yoon 한국생명과학회 2005 생명과학회지 Vol.15 No.3

산성비가 식물 생장에 미치는 영향과 식물의 생화학적 방어반응을 조사하고자 봉선화를 이용하여 인공 산성비(pH 2.0, 3.0, 4.0, 5.6) 실험을 수행하였다. 산성비의 pH가 낮을수록 생육 피해는 심하게 나타났으며 pH 3.0 이하의 처리에 의해 잎에 암회색 또는 적갈색의 괴사반점이 생성되었다. MDA 함량은 pH 2.0 처리에서 약 $40\%$의 증가를 나타내었다. 산성비의 $H^+$ 부하량 증가에 따라 산화형인 DHA 및 GSSG의 함량이 증가하였다. 항산화효소인 SOD, APX, DHAR, GP등의 활성도 산성비의 $H^+$ 부하량의 증가에 따라 크게 증가하는 것으로 나타났다. 이상의 결과로 볼 때 산성비는 봉선화 식물에 활성산소 생성에 의한 산화스트레스를 일으키며, 이를 무독화하기 위해 식물의 생화학적 방어반응이 작용하는 것으로 사료된다 To investigate the effects of simulated acid rain (SAR) on growth and biochemical defense responses of plant, garden balsam (Impatiens balsamina L.) was subjected to four levels of SAR based on pH (5.6, 4.0, 3.0, 2.0) and placed in the growth chambers for 2 weeks. SAR drastically inhibited both height and dry weight of garden balsam. The content of total carotenoid was tended to decrease, but the level of malondialdehyde was significantly increased by SAR. As the pH levels decreased from 5.6 to 2.0, the content of dehydroascorbate and oxidized glutathione of the plant were significantly increased. The enzyme (superoxide dismutase, ascorbate peroxidase etc.) activities of the plant affected by SAR were increased as the pH decreased. The results indicate that garden balsam may receive oxidative stresses by the application of SAR and by which the plant growth can be significantly retarded. A biochemical protective mechanism might be activated to nullify the oxidative stresses generated through SAR.

蟲垂炎에 있어서의 淋巴濾胞의 數 및 그 態度

金學潤(Hak Yoon Kim),崔元(Wone Choi) 대한외과학회 1970 Annals of Surgical Treatment and Research Vol.12 No.2

간농양의 임상적 고찰

김학윤(Hak Yoon Kim),박원회(Y.H. Park),박춘봉(C.B. Park) 대한소화기학회 1972 대한소화기학회 추계학술대회 Vol.1972 No.-

N/A

出血性 消化性 潰瘍의 外科的 考察

金學潤(Hak Yoon Kim),李喜萬(Hee Man Lee),金光?(Kawng Lock Kim) 대한외과학회 1970 Annals of Surgical Treatment and Research Vol.12 No.2

La(Ⅲ)로 표면처리된 메조포러스 실리카에 의한 불소(F) 및 인(P)의 흡착 동력학적 특성 연구

김학윤 ( Hak-yoon Kim ),노백호 ( Paik-ho Rho ),김정배 ( Jeung-bea Kim ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.3

La(Ⅲ)-impregnated mesoporous silica(La-MS) adsorbent has been developed for the removal of F and P ions by adsorption. These adsorbent have been characterized by zeta potential, XRD and SEM analysis. To elucidate the surface characteristic of adsorbent, the zeta potentials were measured. As a result of zeta potential data, mesoporous silica(MS) indicated that the surface potentials seem to be dependent on the pH and the -15∼-55㎷ showed in the range of all pH. Otherwise, the surface potentials of La-MS indicated that the +50∼-40㎷ charge at the range of all pH. La-MS was tested for the removal of F and P ions from aqueous solution. Experiments were carried out as a function of pH and anion concentration in aqueous phase. The equilibrium time was 120min and equilibrium experiment data obeyed the pseudo second order kinetic model. The Langmuir model and Temkin model represented the experimental data as well. The maximum adsorption capacity of F and P ions calculated from Langmuir isotherm model was 22.24㎎/g and 23.86㎎/g, respectively. From calculated Temkin constant(B=2.857∼3.503J/㏖), this adsorption process is physical adsorption. The mechanism of the adsorption process showed that adsorption was dependent on intra particle diffusion model according to two step diffusion. To estimated thermodynamic parameters(△H0, △S0 and △G0) indicated that the adsorption was spontaneous and endothermic. The removal selectivity by La-MS was in order by F < P.

오존층 파괴에 의한 자외선 중가가 식물에 미치는 영향

Hak Yoon Kim(김학윤),Moon Soo Cho(조문수) (사)한국생물환경조절학회 2001 생물환경조절학회지 Vol.10 No.3