암모니아 공정에서 CO₂ 고정의 최적화

서성규,이정섭,송준석 國立麗水大學校 環境問題硏究所 2004 環境硏究論文集 Vol.6 No.-

This study was investigated the effects of various system parameters on the absorption of carbon dioxide into absorption solution. An aqueous potassium carbonate solution was used as a chemical absorbent in order to figure out the effect of chemical reaction. For this purpose, the chemical analysis of potassium carbonate solution was performed. The changes of pressure, temperature, K₂CO₃solution flow/feed gas ratio and solution concentration in the absorber and the changes of pressure and temperature in the stripper were also analyzed. The analysis result shows that K₂CO₃ concentration in potassium carbonate solution was 99.6%. The optimum pressure was found to be 27.0㎏/㎠ and the optimum temperature was to be 68℃, the optimum concentration of potassium carbonate solution was to be 26.0wt% in the absorber. The CO₂ leakage decreased with the increment of the K₂CO₃ solution flow/feed gas ratio. But the H₂ leakage in the CO₂ product increased at or above the K₂CO₃ solution flow/feed gas ratio of 1.10. This H₂ leakage induced by the loss of ammonia production. The effects of the changes of the operation condition of the CO₂ stripper to the K₂CO₃ conversion are as follows. The K₂CO₃ conversion decreased as the pressure decreased. The K₂CO₃ conversion increased as the temperature increased. However, increasing the temperature without decreasing the pressure did not bring positive effect. The optimum pressure was found to be 0.45㎏/㎠.

SS400강 용접부의 파괴인성치에 관한 연구

국정한,송일규,김봉중,오세용,성호현 한국기술교육대학교 1999 論文集 Vol.6 No.1

In this work, we studied the mechanical properties, structure and the stress intensity factor of the welded areas which were annealed from 500。C to 900。C with an interval of 100。C. The main results are as follow. 1. The as-welded specimen showed the highest tensile strength and yield point. The tensile strength and the yield point decrease as the annealing temperature increased from 500。C to 900。C, and they became smaller in the order of deposited metal, heat affected zone and base metal. 2. The hardness was maximum at about 9 mm from the welding center line, and it decreased drastically in the heat affected zone located between 9∼15mm from the center line. 3. The elongation decreased in the order of base metal, the fusion zone and heat affected zone while it increased as annealing temperature increased. 4. The stress intensity factor(S. I. F.) declined as the length of notch increased and it became smaller in the order of fusion zone, base metal and heat affected zone. This is because fracture toughness is affected by brittlization at heat affected zone as well as the initiation and propagation of cracks.

이종재료 접합부 선단의 크랙 전파 거동

국정한,성호현,송일규 한국기술교육대학교 1997 論文集 Vol.4 No.1

In this study, the crack behavior around the bonded dissimilar materials is analyzed by using by Finite Element Method(FEM) in case that it approaches or passes through the bonded line perpendicularly. The analysis criterion is based on the energy(△U) when the crack progresses or passes through the bonded line. The variables are the width of dissimilar material and distance from the crack tip to the bonded line. Values of E(Young's modulus), V(Poisson's ratio) and △U(Energy) for base material are different from those(E', V', △U') for dissimilar material. The outcome of this study is obtained by comparing △U with △U'

국균세포벽을 모델로 한 새로운 고정화담체의 개발

유은정,김종덕,송상호,임현수,최명락,정규화 여수대학교 1997 論文集 Vol.11 No.2

The purpose of this investigation was to develop a new carrier using chitin and glucan as the model for Aspergillus oryzae cell wall. In case of the ratio of chitin and glucan(3/1), the activity of the immobilized protease had higher than that of model(chitin/glucan=1/3) and carriers were formed gel. In case of soluble chitin and glucan treated with calcium carbonate, there were a 1.8-fold increase in activity of immobilized protease compared with untreated chitin. The scanning electron microscope image showed that a pore size of this carrier had a homogenized pore size and a smooth surface.

소성변형 부위에서의 피로크랙전파

성호현,송일규,국정한 한국기술교육대학교 1998 論文集 Vol.5 No.1

In this study, the behavior of a fatigue crack propagation near the expanded hole was investigated in terms of the plastic deformation and position of hole with respect to the propagating crack tip. The results of this study are summarized as follows. 1. The crack propagation rate is high when the crack tip approaches the hole but the retardation effect becomes prolonged when the crack tip is at the very vicinity of the hole. 2. The proper expansion of the hole seemed to play an important role for the retardation of the fatigue crack propagation rate. It is found that 5% of plastic deformation in mild steel show the best effect of the fatigue crack retardation.

임피던스 방법을 이용한 뇌혈류량 측정기기의 개발(Ⅰ)

김덕원,김정래,송철규,김정열,남문현 대한의용생체공학회 1989 의공학회지 Vol.10 No.1

In this study, Rheoencephalography(REG) was designed and constructed. Using the constructed instrument cerebral blood flow(CBF) of left and right brain, CBF change by posture, and reproducibility were studied. Followings are important results. Relative CBF could be measured noninvasively and continuously. Since reproducibility of the constructed REG was found to be quite high (4 %), the accuracy of the instrument itself was proved. REG can be easily applied for testing the effect of drugs for the patients with cerebral vessel diseases since it is quite sensitive to the relative changes of CBF. Various cerebral diseases can be diagnosed by analyzing the REG waveforms. The area of restricted cerebral blood vessels can be located by arranging the electrode configuration. Comparative studies with the standard techniques of measuring CBF are needed to verify the accuracy of REG. Further studies on optimal electrode configuration and various artifacts are also necessary.

즉흥사고를 이용한 글쓰기 전략 개발 연구

김재수,임성규,김재봉,정경미 광주교육대학교 초등교육연구소 2001 初等敎育硏究 Vol.15 No.2

The purpose of this study was to develop an writing strategy with brainstorming. Concrete instructional contents for the dvelopment of writing strategy with brainstorming and the continuous application of the strategy to the whole writing's processes were developed here. And its method of application to elementary school and university were also described. The modern writing theory which reflects the importance of thinking had emphasis on the diversification of thinking ability. From this point of view, brainstorming which is adopted to a way of enhancing thinking ability was applied to students' writings. Brainstorming aims to pull out the unique idea from the consciousness of students and this study tried to develop continuous model of writing strategy through brainstorming. The advantage of continuous model could be in teaching the students interactively for whole writing processes. This study showed that brainstorming could be applied to the whole writing process, idea production - idea construction - paragraph writing, and described the results of its application at the order of method - application - consideration of instruction.

교육사회학의 연구 동향 분석

김경식,권민석,김병규,박형진,송승면,황정희 경북대학교 사범대학부속 중등교육연구소 2005 중등교육연구 Vol.53 No.3

한국, 일본, 미국, 영국의 교육사회학 학술지 논문을 주제별 내용분석을 통해 각각의 하위개념을 도출하고 개념의 유사성의 정도에 따라 다시 상위개념으로 분류하여 교육사회학의 주요 연구영역을 탐색하였다. 학술지에서 가장 많이 다루어진 영역은 교육과 평등/지위획득, 교육정책과 제도, 교육사회학의 성격/이론, 학교사회와 학업성취, 페미니스트(여성), 청소년 문제와 문화, 교사교육/교직사회, 공교육의 문제/교육개혁 등의 순으로 나타났다. 특히 교육정책과 제도 문제는 한국과 일본에서, 교육사회학의 발달과 정체성 문제는 영국에서, 학업성취 관련 내용은 미국에서 가장 많이 다루어졌다. The purpose of this study was to explore the research trend in sociology of education. To conduct the purpose of this study, the Korean Journal of Sociology of Education(KJSE), the Journal of Educational Sociology(JES), Sociology of Education(SOE), and Bitish Journal of Sociology of Education(BJSE)'s articles were analyzed. The findings of this study were as follows: First, though the major categories(major domains) of research areas were a few differences among nations, they were education & equality, educational policy, sociology of education theory, school society & academic achievement, feminism, adolescent problem & culture, teacher education, school crisis & education reform, course education, sociology of curriculum, and etc. Second, the most frequent research area was the educational policy & system problems in Korea and Japan; the development and identity of sociology of education in Britain; The school society & academic achievement in U.S.A.

Catalytic chemical vapor deposition of large-area uniform two-dimensional molybdenum disulfide using sodium chloride

Song, Jeong-Gyu,Hee Ryu, Gyeong,Kim, Youngjun,Je Woo, Whang,Yong Ko, Kyung,Kim, Yongsung,Lee, Changseung,Oh, Il-Kwon,Park, Jusang,Lee, Zonghoon,Kim, Hyungjun IOP Pub 2017 Nanotechnology Vol.28 No.46

<P>The effective synthesis of atomically thin molybdenum disulfides (MoS<SUB>2</SUB>) of high quality and uniformity over a large area is essential for their use in electronic and optical devices. In this work, we synthesize MoS<SUB>2</SUB> that exhibit a high quality and large area uniformity using chemical vapor deposition (CVD) with volatile S organic compound and NaCl catalysts. In the latter process, the NaCl enhances the growth rate (5 min for synthesis of monolayer MoS<SUB>2</SUB>) and purity of the synthesized MoS<SUB>2</SUB>. The optical microscopy, Raman spectroscopy, x-ray photoemission spectroscopy, photoluminescence, and transmission electron microscopy measurements indicate that the NaCl-CVD MoS<SUB>2</SUB> has a large grain size, clear Raman shift, strong photoluminescence, good stoichiometry, and 6-fold coordination symmetry. Moreover, we demonstrate that the electron mobility (10.4 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>) and on/off current ratio (3?×?10<SUP>7</SUP>) of monolayer MoS<SUB>2</SUB> measured using a field-effect transistor are comparable to those of previously reported MoS<SUB>2</SUB> synthesized using CVD.</P>

Vapor Deposition Techniques for Synthesis of Two-Dimensional Transition Metal Dichalcogenides

Song, Jeong-Gyu,Park, Kyunam,Park, Jusang,Kim, Hyungjun Korean Society of Microscopy 2015 Applied microscopy Vol.20 No.1

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted significant attention due to their unique and exotic properties attributed to their low dimensionality. In particular, semiconducting 2D TMDCs such as $MoS_2$, $WS_2$, $MoSe_2$, and $WSe_2$ have been demonstrated to be feasible for various advanced electronic and optical applications. In these regards, process to synthesize high quality 2D TMDCs layers with high reliability, wafer-scale uniformity, controllable layer number and excellent electronic properties is essential in order to use 2D TMDCs in practical applications. Vapor deposition techniques, such as physical vapor deposition, chemical vapor deposition and atomic layer deposition, could be promising processes to produce high quality 2D TMDCs due to high purity, thickness controllability and thickness uniformity. In this article, we briefly review recent research trend on vapor deposition techniques to synthesize 2D TMDCs.