• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.591-594
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• 1988

A three-step heuristic algorithm for PLA column folding and row folding of column-folded PLA is presented, which is significantly faster than the earlier works and provides nearly optimal results. The three steps are i) min-cut partition of vertices in the column (or row) intersection graph, ii) determination of products' order using Fiduccia's min-net cut algorithm, and iii) head-tail pairing for column folding, while some heuristics are proposed for deciding row folding pairs. The time complexity of this algorithm is O($n^{2}$log n) compared to the O($n^{3}$) - O($n^{4}$) of the earlier works.$^[2][3][9]$ For a test PLA with 23 inputs, 19 outputs and 52 products, the number of column folding pairs obtained using this algorithm is 20 which is optimal, as compared to 17 in a previous work.

• 소성∙가공
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• 제8권2호
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• pp.135-142
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• 1999

Tube Process(TP) is one of the processes to produce permanent magnets. Advantage claimed for this process is that it can accmplish both densification and anisotropication in one step forming. This process is distinguished from other processes since it uses deformable tube for densification of powder magnets. TP has, however, difficulties in manufacturing permanent magnets from Nd-Fe-B green powder due to folding resulted from large height reduction and localized densification. Therefore, an adequate preform is necessary to reduce folding resulted from large height reduction and localized densification. Therefore, an adequate preform is necessary to reduce folding, lead magnets into almost desired final shape and get uniform densification. In this paper, preform design for TP is carried out without a deformable tube to investigate the behaviour of magnet sinter-forging. Preform design is accomplished to increase the effective magnet area with a near net shape and uniform densification.

• 한국환경과학회지
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• 제11권5호
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• pp.419-436
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• 2002

The current paper reports on the enhancement of O$_3$, CO, NO$_2$, and aerosols during the Asian dust event that occurred over Korea on 1 May 1999. To confirm the origin and net flux of the O$_3$, CO, NO$_2$, and aerosols, the meteorological parameters of the weather conditions were investigated using Mesoscale Meteorological Model 5(MM5) and the TOMS total ozone and aerosol index, the back trajectory was identified using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model(HYSPLIT), and the ozone and ozone precursor concentrations were determined using the Urban Ashed Model(UAM). In the presence of sufficiently large concentrations of NO$\sub$x/, the oxidation of CO led to O$_3$ formation with OH, HO$_2$, NO, and NO$_2$ acting as catalysts. The sudden enhancement of O$_3$, CO, NO$_2$ and aerosols was also found to be associated with a deepening cut-off low connected with a surface cyclone and surface anticyclone located to the south of Korea during the Asian dust event. The wave pattern of the upper trough/cut-off low and total ozone level remained stationary when they came into contact with a surface cyclone during the Asian dust event. A typical example of a stratosphere-troposphere exchange(STE) of ozone was demonstrated by tropopause folding due to the jet stream. As such, the secondary maxima of ozone above 80 ppbv that occurred at night in Busan, Korea on 1 May 2001 were considered to result from vertical mixing and advection from a free troposphere-boundary layer exchange in connection with an STE in the upper troposphere. Whereas the sudden enhancement of ozone above 100 ppbv during the day was explained by the catalytic reaction of ozone precursors and transport of ozone from a slow-moving anticyclone area that included a high level of ozone and its precursors coming from China to the south of Korea. The aerosols identified in the free troposphere over Busan, Korea on 1 May 1999 originated from the Taklamakan and Gobi deserts across the Yellow River. In particular, the 1000m profile indicated that the source of the air parcels was from an anticyclone located to the south of Korea. The net flux due to the first invasion of ozone between 0000 LST and 0600 LST on 1 May 1999 agreed with the observed ground-based background concentration of ozone. From 0600 LST to 1200 LST, the net flux of the second invasion of ozone was twice as much as the day before. In this case, a change in the horizontal wind direction may have been responsible for the ozone increase.

• Applied Biological Chemistry
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• 제46권4호
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• pp.305-310
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• 2003

Hydrophobic core가 변이된 유비퀴틴 단백질이 pH 2 용액에서 보이는 구조적인 특성을 여러 분광학적 방법으로 측정하였다. 낮은 pH값을 갖는 용액에서 이 변이 유비퀴틴의 intrinsic tryptophan fluorescence emission spectrum은 unfolded 상태보다 약간 blue shift되어 있고 또한 그 intensity도 상당히 낮게 나타났다. 이는 이 용액 조건에서 이 변이 유비퀴틴의 삼차구조가 약간 남아 있는 것을 의미한다. 같은 용액에서 이 변이 유비쥐틴의 far-UV circular dichroic spectrum은 native 상태나 unfolded 상태의 spectrum과 현저히 달랐으며 220 nm 에서의 molar ellipticity 값을 통하여 볼 때 pH 2인 용액에서 상당량의 이차구조를 지니고 있었다. 또한 같은 용액에서 이 변이 유비퀴틴은 hydrophobic dye인 8-anilinonaphthalene-1-sulfonic acid(ANS)외 fluorescence emission intensity를 증가시키고 fluorescence emission maximum이 짧은 파장에서 나타나게 하였다(blue shift). 이러한 현상은 pH 2 용액에서 이 변이 유비퀴틴의 hydrophobic core가 느슨하여져서 hydrophobic dye인 ANS가 결합할 수 있는 구조를 띠고 있음을 나타낸다. 이러한 분광학적인 관찰은 이 변이 유비귀틴이 pH 2인 용액에서 상당량의 이차구조를 지니고 있지만 hydrophobic core는 느슨하게 형성된 molten globule과 같은 형태를 지니고 있음을 나타낸다. 이 변이 유비퀴틴의 molten 히obule 형태는 단백질 폴딩 반응의 경로를 연구할 수 있는 좋은 모델이 될 수 있을 것으로 생각된다.

• 터널과지하공간
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• 제18권3호
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• pp.185-193
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• 2008

이 연구에서는 시추공 분석 작업을 통해 획득된 암반절리 방향성이 심도에 따라 변화하는 양상의 확인을 위해 피어슨 카이제곱 통계검정이 실시되었다. 대상 암반은 모암이 화강암질 편마암인 두 지역으로서, 이와같은 엽리가 발달하지 않은 괴상의 암상 선정은, 엽리가 존재하는 암석의 경우 절리 방향성이 엽리에 의해 영향을 받고 엽리의 방향은 습속 등의 지질작용에 의해 심도에 따라 다를 수가 있기 때문이다. 암반 절리들의 방향 파악을 위해 시추공 영상이 이용되었다. 획득된 방향자료를 천부구간과 심부구간의 자료로 분류한 후 21 영역으로 구성된 분할망에 각각 투영 후, 분류표를 작성하여 통계검정을 실시하였으며, 분석결과 두 지역 중 한 지역의 자료는 비동질로 나타났다. 이러한 결과는 터널과 같은 지하구조물의 설계를 위한 암반공학적으로 중요한 절리면의 방향성에 대한 조사시 원위치 조사가 바람직함을 시사한다.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제23권2호
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• pp.297-312
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• 2009

다면체에 관한 연구 문제를 통해 수학사를 통한 문제 제기, 컴퓨터와 교구 등을 통한 수학실험, 추측, 그리고 정당화를 통한 수평적 수학화와 수직적 수학화의 과정을 다룬다. 구체적으로 본 논문에서는 아르키메데스 다면체와 카탈란 다면체를 중심으로, 수학사를 통해 등장하는 해밀턴 경로 문제, 다면체 색칠 문제, 그리고 다면체 전개도를 통한 구성 문제 등을 컴퓨터와 교구 등을 통해 수학실험으로 탐구하고, 추측과 정당화의 과정을 통해 얻어진 결과를 보고하며 또한 수학실험을 통해 발견된 미해결 문제를 제시한다.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.103-113
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• 2014

Hydrophobicity is the key concept to understand the role of water in protein folding, protein self-assembly, and protein-ligand interaction. Conventionally, hydrophobicity of amino acids in a protein has been argued based on hydrophobicity scales determined for individual free amino acids, assuming that those scales are unaltered when amino acids are embedded in a protein. Here, we investigate how the hydrophobicity of constituent amino acids depends on the protein context, in particular, on the total charge and secondary structures of a protein. To this end, we compute and analyze the hydration free energy - free energy change upon hydration quantifying the hydrophobicity - of three short proteins based on the integral-equation theory of liquids. We find that the hydration free energy of charged amino acids is significantly affected by the protein total charge and exhibits contrasting behavior depending on the protein net charge being positive or negative. We also observe that amino acids in the central ${\beta}$-strand sandwiched by ${\beta}$-sheets display more enhanced hydrophobicity than free amino acids, whereas those in the ${\alpha}$-helix do not clearly show such a tendency. Our results provide novel insights into the hydrophobicity of amino acids, and will be valuable for rationalizing and predicting the strength of water-mediated interaction involved in the biological activity of proteins.

• 한국학교수학회논문집
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• 제9권2호
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• pp.229-248
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• 2006

이 글은 컴퓨터 환경에서의 유창성 교육에 대하여 논의한다. 여기서 유창성이란 컴퓨터 환경, 기술 정보 환경을 이용하여 지식을 재조직하고, 창의적이고 적절한 방법으로 자신을 표현하고, 정보를 단지 이해하기 보다는 생산하거나 만드는 능력을 말한다. 이 글은 구성주의적 입장에서 유창성 교육의 의미와 유창성 교육을 위한 학습 전략으로 디자인을 통한 학습에 대하여 살펴본다. 또한 디자인을 통한 학습 환경으로 수학교육용 마이크로월드의 설계 원칙을 생각하고 이를 적용하여 마이크로월드를 구현한다. 마지막으로 이 환경에서의 학습-지도 사례를 제시하여 그 의미를 생각한다.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1022-1028
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• 2024

A neutronics study of a supercritical CO₂-cooled fast reactor core for nuclear propulsion has been performed in this work. The thermal power of the reactor core is 30 MWth and a ceramic UO₂ fuel can be used to achieve a 20-year lifetime without refueling. In order to make a compact core with inherent safety features, the drum-type reactivity control system and folding-type shutdown system are adopted. In addition, we suggest a cold shutdown system using gadolinium as a spectral shift absorber (SSA) against flooding. Although there is a penalty of U-235 enrichment for the core embedded with the cold shutdown system, it effectively mitigates the increment of reactivity at the flooding of seawater. In this study, the neutronics analyses have been performed by using the continuous energy Monte Carlo Serpent 2 code with the evaluated nuclear data file ENDF/B-VII.1 Library. The supercritical CO₂-cooled fast reactor core is characterized in view of important safety parameters such as the reactivity worth of reactivity control systems, fuel temperature coefficient (FTC), coolant temperature coefficient (CTC), and coolant temperature-density coefficient (CTDC). We can say that the suggested core has inherent safety features and enough flexibility for load-following operation.

• 자원환경지질
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• 제10권1호
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• pp.37-48
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• 1977

The earth's crust is unceasingly undergoing deformations because of the forces acting upon it. The relationship between the tectonic forces and the resulting deformations are found from the states of stresses in the earth's crust induced by these forces. The study has been attempted to analyze the deformations of the overlying sedimentary layers, which are deformed by the magma intrusion along its lower boundary. The elastic model is constructed to analyze the geologic structures, by means of the theory of elasticity, and then the appropriate boundary conditions are given. The solution of the Airy stress function which satisfies the given boundary conditions is derived from the analytic method. The internal stress distributions of the deformed elastic model layer are portrayed by principal stress trajetories, and then the corresponding potential faults and joints systems are predicted from the Coulomb-Mohr failure criterion. The internal displacement distributions are shown by the calculated displacement components vectors, namely horizontal, vertical and net components. Results of the numerical calculations show the developments of some geologic structures as follows; (1) one set of shear joints and or two sets of shear joints which are oppisite directions, and one set of extension joints parallel to the ${\sigma}_1$ direction, (2) one set of high angle thrusts and normal faults, (3) symmetric fold; both limbs are dipping in opposite direction with low angle. The field work at the Wall-A San area, located near Jinju City, in southern Korea, had accomplished to compare the field structures with the predicted ones. The results of the comparison exhibits the developments of joint and fault systems satisfactorily consistent with each others. But the area does not show any type of folding, in spite of the intrusion of a granodiorite massif, this fact is one of the important features of the whole Kyungsang sedimentary basins of Mesozoic age distributed at the south-eastern parts of Korea. For this reason, it is thought that the magma intrusion had occurred with extremly low pressure. The geologic structures have been modified by the erosion and weathering throughout the geologic time, and the conditions of the sedimentary layers (width, thickness and radius of magma) are not the same as before, being intruded by the magma. To enlighten this, it is preferable to study these geologic structures with analyses of various types of rheological models.