N과 AlN 시트에 다양한 기체(CO_x, NO_x, SO_x)의 흡착에 관한 이론 연구

김성현,김백진,신창호,김승준,Kim, Sung-Hyun,Kim, Baek-Jin,Shin, Chang-Ho,Kim, Seung-Joon 대한화학회 2017 대한화학회지 Vol.61 No.1

본 연구는 그래핀과 유사한 2차원 붕소-질소(BN)와 알루미늄-질소(AlN) 시트에 여러 대기 유해 가스($CO_x$, $NO_x$, $SO_x$)가 흡착될 때의 구조적 특징과 결합에너지를 밀도 범함수 이론(DFT)과 MP2 방법을 사용하여 연구하였다. 분자 구조는 $B3LYP/6-31G^{**}$와 $CAM-B3LYP/6-31G^{**}$이론 수준에서 최적화하고, 진동 주파수를 계산하여 열역학적으로 가장 안정한 분자 구조를 확인하였다. 결합에너지는 $MP2/6-31G^{**}$ 이론 수준에서 한 점(single point) 에너지를 계산하고, 영점 진동에너지(ZPVE)와 바탕집합 중첩에러(BSSE)를 모두 보정하였다. BN 시트에 가스의 흡착은 모두 물리흡착으로 예측되었으며, AlN 시트에 대한 가스 흡착은 $CO_x$나 $NO_x$에 대해서는 물리흡착이 그리고 $SO_x$에 대해서는 화학 흡착이 일어날 것으로 예측되었다. The adsorption of various atmospheric harmful gases ($CO_x$, $NO_x$, $SO_x$) on graphene-like boron nitride(BN) and aluminum nitride(AlN) sheets was theoretically investigated using density functional theory (DFT) and MP2 methods. The structures were fully optimized at the $B3LYP/6-31G^{**}$ and $CAM-B3LYP/6-31G^{**}$ levels of theory and confirmed to be a local minimum by the calculation of the harmonic vibrational frequencies. The MP2 single-point binding energies were computed at the $CAM-B3LYP/6-31G^{**}$ optimized geometries. Also the zero-point vibrational energy (ZPVE) and 50%-basis set superposition error (BSSE) corrections were included. The adsorptions of gases on the BN sheet were predicted to be a physisorption process and the adsorptions of gases on the AlN sheet were predicted to be a physisorption process for $CO_x$ and $NO_x$ but to be a chemisorption process for $SO_x$.

풀러렌-물 클러스터의 상호작용에 대한 양자 역학적 이론 연구

김성현,신창호,김지선,강소영,김승준,Kim, Sung-Hyun,Shin, Chang-Ho,Kim, Ji-Sun,Kang, So-Yung,Kim, Seung-Joon 대한화학회 2015 대한화학회지 Vol.59 No.1

풀러렌(fullerene)의 내부에 캡슐화될 수 있는 물 분자의 수와 물 분자들이 증가함에 따라 풀러렌의 안정적인 구조에 미치는 영향을 조사하기 위해 밀도 범함수 이론(density functional theory, DFT)을 이용하여 풀러렌-물 클러스터$(H_2O)_n@C_{60}$, (n=1-10)의 구조 변화에 따른 열역학적 안정성 및 결합에너지를 계산하였다. 각각의 구조들에 대해서 여러 이론 수준에서 최적화하였으며 진동주파수를 계산하여 가장 안정한 구조를 조사하고 IR 스펙트럼을 예측하였다. 또한 풀러렌 내의 물 분자 수가 증가함에 따른 수소결합의 세기 변화를 순수한 물 클러스터$(H_2O)_n$, (n=1-6)의 수소결합과 비교 분석하였다. The density functional theory (DFT) calculations on $(H_2O)_n@C_{60}$, (n=1-10) complexes have been performed to elucidate hydrogen interaction between fullerene and water clusters. The optimized geometries, harmonic vibrational frequencies, and binding energies are predicted at various levels of theory. The harmonic vibrational frequencies for the molecules considered in this study show all real numbers implying true minima. We also compare the H-bond interaction between $(H_2O)_n$ and $(H_2O)_n@C_{60}$, (n=1-10) clusters.

골절 방지 시스템의 개발을 위한 낙상 시뮬레이션과 충격 흡수 시스템에 관한 연구

김성현,김동욱,김남균,Kim, S.H.,Kim, D.W.,Kim, N.G. 대한의용생체공학회 2010 의공학회지 Vol.31 No.6

The social activities of the elderly have been increasing as our society progresses toward an aging society. As their activities are increased, the occurrence of falls that could lead to fractures are increased. Falls are serious health hazards to the elderly and we need more thorough understanding of falls including the progress of falls and the impact area in various fall directions. Many of the traditional methods of falls research dealt with voluntary falls by younger subject since older subject can easily get fracture from voluntary falls. So, it has been difficult to get exact data about falls of the elderly. Here, we tried to capture the characteristics of the movements of major joints using three dimensional motion capture system during falls experiments using a moving mattress that can safely induce unexpected falls. Healthy younger subjects participated in the actual falls experiment and the moving mattress was actuated by a pneumatic system. The kinematic parameters such as velocities of major segments were imported to a computer simulation environment and falls to hard surfaces were simulated in a computational environment using a realistic human model of aged persons. The simulation was able to give approximations to contact forces which can occur during actual falls. And we designed impact absorption system to reduce the impact during falls. We can adapt this system to fracture prevention system that we are going to study.

치주치료 후 구강 내 Volatile Sulfur Compounds(VSC)의 변화

김성현,채경준,정의원,김창성,최성호,조규성,채중규,김종관,방은경,Kim, Sung-Hyun,Chae, Gyeong-Jun,Jung, Ui-Won,Kim, Chang-Sung,Choi, Seong-Ho,Cho, Kyoo-Sung,Chai, Jung-Kyu,Kim, Chong-Kwan,Bang, Eun-Gyeong 대한치주과학회 2006 Journal of Periodontal & Implant Science Vol.36 No.3

Oral malodor may cause a significant social or psychological handicap to those suffering from it. Oral malodor has been correlated with the concentration of volatile sulfur compounds (VSC) produced in the oral cavity. Specific bacteria identified in the production of VSC have been reported and many of these bacteria are commonly suspected periodontal pathogens. The aim of this study was to estimate the change of the VSC concentration after periodontal treatment, Twenty subjects with probing depth $(PD)\;{\geq}5mm$ (experimental group) and 20 subjects with PD<5mm (control group) participated. VSC concentration measurement was made with gas chromatography. VSC concentration was measured at pre-treatment, 2 weeks after scaling and 1 month after periodontal treatment(root planning and flap operation). Maximum probing depth and bleeding on probing(BOP) were also examed at pretreatment and 1 month after periodontal treatment, The conclusions were as follow: 1. In the experimental group VSC concentration and CH3SH/H2S ratio were higher than control group. (p<0.05) 2. Both VSC concentration and CH3SH/H2S ratio showed decrease after periodontal treatment, But only CH3SH/H2S ratio after 1 month periodontal treatment was statistically significantly different from pre-treatment. (p<0.05) 3. CH3SH/H2S ratio tended to be on increase according to maximum probing depth and bleeding on probing. Periodontal disease could be a factor that caused oral malodor and oral malodor could be decreased after periodontal treatment.

기후변화와 선박에너지효율

김성현,Kim, Seong-Hyeon 대한조선학회 2016 大韓造船學會誌 Vol.53 No.1

FR4 PCB면적과 Via-hole이 LED패키지에 미치는 열적 특성 분석

김성현,이세일,양종경,박대희,Kim, Sung-Hyun,Lee, Se-Il,Yang, Jong-Kyung,Park, Dae-Hee 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.3

In this study, the heat transfer capability have been improved by using via-holes in FR4 PCB, when the LED lighting is designed to solve the thermal problem. The thermal resistance and junction temperature were measured by changing the dimension of FR4 PCB and size of via hole. As a result, when the dimension was increased initially, the thermal resistance and junction temperature was decreased rapidly, the ones was stabilized after the dimension of 200 $[mm^2]$. Also, the light output was improved up to maximum 17% by formation of via-hole and expansion of dimension in FR4 PCB. Therefore, the thermal resistance and junction temperature could be improved by expansion of PCB dimension and configuration of via-hole ability.

소나무(Pinus densiflora) 묘목의 생장에 미치는 납과 CO₂의 영향

김성현,홍선화,강호정,류희욱,이상돈,조경숙,이인숙,Kim, Sung-Hyun,Hong, Sun-Hwa,Kang, Ho-Jeong,Ryu, Hee-Wook,Lee, Sang-Don,Cho, Kyung-Suk,Lee, In-Sook 한국생태학회 2006 Journal of Ecology and Environment Vol.29 No.6

본 연구는 $CO_2$ 증가와 Pb 오염이 소나무 묘목에 미치는 영향에 대하여 조사하였다. 납 오염 토양(500 mg/kg-soil)과 비오염토양에 2년생 소나무를 식재한 후, $CO_2$ 농도를 380 PPM 혹은 760 ppm으로 조절한 배양기에서 3개월간 생육시킨 후, 소나무 묘목의 성장, 납 함량 변화 및 토양의 물리 화학적 변화를 조사하였다. 소나무의 생체량과 뿌리 길이는$CO_2$ 농도에 따라 유의적인 차이를 보이지 않았으나, 납에 의한 저해는 뚜렷이 나타났다. 납 오염 토양에서 토양중의 납 잔류랑은 $CO_2$ 농도에 영향을 받지 않았으나, 소나무 뿌리중의 축적량은 $CO_2$ 농도가 높으면 2배 정도 높았다. 이러한 결과는 $CO_2$ 농도 증가가 소나무 뿌리의 Pb 생물 이용성에 영향을 미치는 것을 시사한다. This work was investigated the effects of the elevated $CO_2$ and Pb contamination on the growth of Pinus densiflora. Two-years pine trees were planted in Pb-contaminated soils (500 mg/kg-soil) and uncontaminated soils, and cultivated for 3 months in the growth chamber where $CO_2$ concentration was controlled at 380 or 760 ppmv. The growth of P. densiflora were comparatively analyzed in 4 kinds of soil samples (CA : $CO_2$ 380 ppmv + Pb 0 mg/kg, CB : $CO_2$ 380 ppmv + Pb 500 mg/kg, EA : $CO_2$ 760 PPmv + Pb 0 mg/kg, EB : $CO_2$ 760 ppmv + Pb 500 mg/kg). It was measured the growth changes of the p. densiflora caused by $CO_2$ concentration and Pb contamination. The growth of P. densiflora was remarkably inhibited in the Pb-contaminated soil, although the biomass and the root elongations were not significantly affected by the elevated $CO_2$. These results suggested that the growth of p. densiflora was sensitively influenced by Pb contamination rather than $CO_2$ concentration. Compared to the initial soil, total Pb concentration in the soil samples was decreased at 760 ppmv $CO_2$ as well as at 380 ppmv $CO_2$ after 3 months. The accumulation of Pb in the roots at 760 ppmv $CO_2$ was two-fold of that at 380 ppmv $CO_2$, indicating that Pb bioavailability in the root of p. densiflora might be affected by the elevated $CO_2$.

의료기관의 Y2K문제 해결 방안

김성현,Kim, Seong-Hyeon 한국가톨릭의료협회 2000 한국가톨릭병원협회지 Vol.30 No.-

UAV와 ENVI-met을 활용한 공간 유형별 열환경 특성 분석

김성현,박경훈,이수아,송봉근,KIM, Seoung-Hyeon,PARK, Kyung-Hun,LEE, Su-Ah,SONG, Bong-Geun 한국지리정보학회 2022 한국지리정보학회지 Vol.25 No.1

This study classified UAV image-based physical spatial types for parks in urban areas of Changwon City and analyzed thermal comfort characteristics according to physical spatial types by comparing them with ENVI-met thermal comfort results. Physical spatial types were classified into four types according to UAV-based NDVI and SVF characteristics. As a result of ENVI-met thermal comfort, the T_MRT difference between the tree-dense area and other areas was up to 30℃ or more, and it was 19. 6℃ at 16:00, which was the largest during the afternoon. As a result of analyzing UAV-based physical spatial types and thermal comfort characteristics by time period, it was confirmed that the physical spatial types with high NDVI and high SVF showed a similar to thermal comfort change patterns by time when using UAV, and the physical spatial types with dense trees and artificial structures showed a low correlation to thermal comfort change patterns by time when using UAV. In conclusion, the possibility of identifying the distribution of thermal comfort based on UAV images was confirmed for the spatial type consisting of open and vegetation, and the area adjacent to the trees was found to be more thermally pleasant than the open area. Therefore, in the urban planning stage, it is necessary to create an open space in consideration of natural covering materials such as grass and trees, and when using artificial covering materials, it is judged that spatial planning should be done considering the proximity to trees and buildings. In the future, it is judged that it will be possible to quickly and accurately identify urban climate phenomena and establish urban planning considering thermal comfort through ground LIDAR and In-situ measurement-based UAV image correction.

음식물(飮食物)에 의(依)하여 발생(發生)되는 해수(咳嗽)에 대(對)한 문헌적(文獻的) 고찰(考察)

김성현,이준무,한상환,Kim, Sung-Hyun,Lee, Jun-Mu,Han, Sang-Whan 대한한방내과학회 1991 大韓韓方內科學會誌 Vol.12 No.2

This study has been carried out to investigate the cause and symptom of coughing made of foods and wine by referring to 43 literatures. The results were obtained as follows; 1. The factor causing Sik Juk Su ( 食積嗽 ) is Dam Yeum ( 痰飮 ) made from mistaking meals. 2. Excepted Sik Juk Su ( 食積嗽 ), Coughing made of foods and wine are Bi Hae ( 脾咳 ), Uey Hae ( 胃咳 ), Dam Su ( 痰嗽 ). Ju Su ( 酒嗽 ). Han Su (寒嗽). 3. The symptom of Sik Juk Su ( 食積嗽 ) is as follows. pale-looking cough in early morning pain of right sub-ribs body tired low appetite body fever vomitting acid 4. Excepted Sik Juk Su ( 食積嗽 ), the symptom of Coughing made of foods and wine are simulanted of Sik Juk Su ( 食積嗽 ).