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N과 AlN 시트에 다양한 기체(CO<sub>x</sub>, NO<sub>x</sub>, SO<sub>x</sub>)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 $SO_x$.
김성현,정성택,김현정,백승엽,Kim, Seong Hyun,Jung, Sung Taek,Kim, Hyun Jeong,Baek, Seung Yub 한국금형공학회 2018 한국금형공학회지 Vol.12 No.2
Recently, as machine components and products are getting smaller, it is demanded to develop superprecision production technologies multilaterally. Along with the advancement of production technology, people are paying keener attention to the development of eco-friendly technology and efficient processing technology. Particularly, in many industries related to automobiles, shipbuilding, or airplane components, it is demanded to obtain technology to process multiple micro-holes. On account of this trend, micro-hole processing employing high-power electron beams is rising nowadays, and more interest is being shown in it, too. In Korea, however, the process of manufacturing vaporized amplification sheets influencing high-power electron beam processing technology and the processability considerably has not been developed sufficiently yet. Therefore, this study has applied vaporized amplification sheets manufactured to analyze the processability of high-power electron beams and examine necessity for vaporized amplification sheets.
부모-자녀 간 의사소통 훈련이 중학생의 또래관계기술 및 학교적응에 미치는 효과
김성현(Kim, Sunghyun),백현옥(Baek, Hyunok) 한국학부모학회 2021 학부모연구 Vol.8 No.3
이 연구에서는 부모-자녀 간 의사소통 훈련이 중학생의 또래관계기술 및 학교적응에 미치는 효과를 알아보기 위해 연구가 진행되었다. 본 연구에서는 다음과 같이 연구문제를 설정하였다. 첫째, 부모-자녀 간 의사소통 훈련은 중학생의 또래관계기술에 어떠한 효과 있는가이었고 둘째, 부모-자녀 간 의사소통 훈련은 중학생의 학교적응에 어떠한 효과가 있는가이었다. 본 연구에서의 대상은 G시 소재 중학생 학부모 22명과 중학생 22명이었다. 조사도구로는 또래관계기술척도와 학교적응척도를 사용하였고, 분석방법으로는 빈도, t-검증, 공변량분석(ANCOVA)을 실시하였다. 본 연구의 결과를 살펴보면 첫째, 부모-자녀 간 의사소통 훈련이 중학생의 또래관계기술을 증진시키는 것으로 나타났다. 둘째, 부모-자녀 간 의사소통 훈련은 중학생의 학교적응력을 증진시키는 것으로 나타났다. 이 연구를 통해 부모-자녀 간 의사소통 훈련과 중학생의 또래관계기술, 학교적응과 관련하여 교육현장에서의 시사점을 제공한다고 볼 수 있다. The study was conducted to investigate the effect of parent-child communication training on peer relationship skills and school adaptation of middle school students. The research questions were set as follows. First, what effect did parent-child communication training have on the peer relationship skills of middle school students, and second, what effect did parent-child communication training have on middle school students school adaptation. The subjects of this study were 22 parents of middle school students in G city and 22 middle school students. The peer relationship skill scale and school adaptation scale were used as research tools, and frequency, t-test, and covariate analysis (ANCOVA) were performed as analysis methods. Looking at the results of this study, it was found that parent-child communication training improves the peer relationship skills of middle school students. Second, parent-child communication training was found to enhance middle school students ability to adapt to school. It can be seen that the results of this study provide implications in the educational field regarding communication training between parents and children, peer relationship skills of middle school students, and school adaptation.
김성현(Sung-Hyun, Kim),박종원(Jong-Won, Park),이기천(Gi-Chun, Lee),백민혁(Min-Hyeok, Baek),김재훈(Jae-Hoon, Kim) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.5
A truck that can lift the lid of the loading box using hydraulic or pneumatic cylinders. It is called Wingcar in the related industry in the wingbody vehicle by the name which derives from the appearance that the loader cover is opened like a wing In the domestic market, large-sized commercial vehicles with 2.5 tons or more produce about 60.000 units a year, and 30.000 are produced as wing-body vehicles, about 50%. It is known that it is common in Asia, and it is hard to see it in Europe and North America where the curtain side method is mainstream. It is known that the market size of the hydraulic cylinders for wing body automobile is about 10 times as large as the domestic market for the domestic companies to enter the Japanese market. The seal and packing of cylinder produced in Korea, due to the characteristics of maintain the function for a long-term once it is installed and it is difficult to maintenance through exchange, it should be careful in the design. More than 95% of domestic cylinder seals are manufactured using global brands such as BUSAK, MERKEL and NOK, which is a stumbling block to cost reduction. The hydraulic cylinder rod eye has a process of finishing the deformed roundness by welding the rod eye after the rod roughing and post-processing. Comparing the shape of the load eye. the strain of each part according to the thurst of the hydraulic cylinder for the wing body was checked and compared, and the cylinder load eye suitable for the use environment was selected.
금속 접합 PCB를 적용하여 방열 특성을 개선시킨 높은 전력밀도의 스위칭 정류기 모듈에 관한 연구
김성현(Sung Hyun Kim),백종옥(Jong Ok Baek),안태영(Tae Young Ahn) 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.3
In this paper, the experimental result on switching rectifier module with high power density which improved heat dissipation characteristics by metal bonded PCB was reported with a prototype. The height of the switching rectifier module was lowered under 13mm, and power density was increased to 127W/in³ while the module was designed with maximum output of 700W class. To minimize the internal heat and losses, bridgeless boost converter circuit was applied. As a consequence, the prototype was performed with 97.5% of maximum power transition efficiency and 99.8% of maximum power factor, hence it was confirmed that the prototype was stably operated under its maximum output by transferring the internal loss to outside effectively.