• 한국안광학회지
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• 제19권3호
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• pp.339-344
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• 2014

목적: 본 연구는 BS 프리즘의 반사면을 이용한 주야 조준경의 개발에 관한 것이다. 방법: BS(beam splitting) 프리즘의 반사면의 상하에 도트시표발생부와 LCD 패널을 배치하고, BS 프리즘 전방에는 doublet 형태로 설계된 반사경을 배치하였다. 이렇게 함으로서 도트시표 발생부에서의 도트시표 허상을 관찰자 쪽에 결상시키도록 하는 기능, 외부 목표물 주변부의 정보는 관찰자에게 1배로 보이도록 하는 기능과 LCD 패널의 영상을 직접 관찰자가 볼 수 있게 하는 기능을 가진 새로운 형태의 BS 프리즘을 이용한 주야 조준경을 개발하였다. 결과: BS 프리즘의 반사면이 도트 시표를 반사시키는 도트사이트로서의 역할과 LCD 패널에 디스플레이된 야간 열영상을 관찰자가 관찰할 수 있도록 하는 반사 광학계 역할을 하도록 함으로써 주간에는 도트사이트로서 주간조준경 기능을, 야간에는 열영상 디스플레이 장치로서 야간조준경 기능을 하는 주야 조준경 장치를 개발하였다. 결론: 본 연구에서 우리는 기존의 도트사이트와 기존의 야간조준경을 BS 프리즘을 이용하여 결합함으로서 선택적으로 주야 조준경 역할을 할 수 있는 주야 조준경을 개발하였다. 이렇게 함으로써 우리는 기존의 도트사이트와 야간조준경의 착탈식 조합보다 사격의 신속성을 더욱 높일 수 있으며 총기류에의 장착에 있어서 보다 편리함을 제공해주는 새로운 형태의 BS 프리즘을 이용한 주야 조준경을 설계 개발할 수 있었다.

• 한국자기학회지
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• 제17권3호
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• pp.114-119
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• 2007

[ $bcc-Th_3P_4$ ] 구조를 가지고 있는 단결정 $Nd_3Se_4$를 성장 시킨 후 $4{\sim}300\;K$ 사이의 온도 영역에서 자기감수율을 측정했다. 측정된 자기기감수율을 축퇴된 $Nd^{3+}$ 기저상태가 결정장의 영향을 받아 발생하는 에너지 갈라짐에 의한 이론적인 자기감수율값과 비교했다. 분석 결과 $Nd_3Se_4$ 결정체 안에 있는 $Nd^{3+}$ 이온의 경우에는 결정장에 의한 영향이 거의 없음을 알 수 있었다. 또한 $T_c$가 53 K인 $Nd_3Se_4$의 자발자기화의 온도에 따른 곡선이 J=9/2에 해당하는 Brillouin function과 일치함을 확인했다.

• 한국농공학회지
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• 제26권1호
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• pp.52-72
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• 1984

This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.

• 한국정보통신학회논문지
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• 제7권4호
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• pp.758-766
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• 2003

본 논문에서는 효율적인 비디오 데이터베이스를 구축하기 위하여 카메라와 객체 파라미터를 이용한 트리-기반 계층형 영상 모자이크 시스템을 제시한다. 장면 전환 검출을 위하여 그레이-레벨 히스토그램 차이와 평균 명암도 차이를 이용한 방법을 제시하였다. 카메라 파라미터는 최소 사각형 오류 기법과 어파인 모델을 이용하여 측정하고, 두 입력 영상의 유사성을 측정하기 위하여 차영상을 이용한다. 또한 동적 객체는 매크로 블록 설정에 의하여 검색되고 영역 분할과 4-분할 탐색에 의하여 추출한다. 동적 객체의 표현은 동적 궤도 평가 함수에 의하여 수행되고 블러링을 통하여 부드럽고 완만한 모자이크 영상을 구축한다.

• 한국공작기계학회논문집
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• 제14권1호
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• pp.30-36
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• 2005

This study is to investigate a damage estimation of single edge notched tensile specimens as a function of acoustic emission(AE) according to the uni-directionally oriented carbon fiber/epoxy composites, CFRP In fiber reinforced composite materials, AE signals due to several types of failure mechanisms are typically observed. These are due to fiber breakage, fiber pull-out matrix cracking, delamination, and splitting or fiber bundle breaking. And these are usually discriminated on the basis of amplitude distribution, event counts, and energy related parameters. In this case, AE signals were analyzed and classified 3 regions by AE event counts, energy and amplitude for corresponding applied load. Bath-tub curve shows 3 distinct periods during the lifetime of a single-edge-notch(SEN) specimen. The characterization of AE generated from CFRP during SEN tensile test is becoming an useful tool f3r the prediction of damage failure or/and failure mode analysis.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.603-610
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• 2003

The influence of Poisson's ratio on the tensile strength of brittle materials is neglected in many studies. When brittle materials are loaded in compression or impact, substantial tensile stresses are induced within the materials. These tensile stresses are responsible for splitting failure of the materials. In this paper, the state of stress in a spherical particle due to two diametrically opposed forces is analyzed theoretically. A simple equation for the state of stress at the center of the particle is obtained. An analysis of the distribution of stresses along the z-axis due to distributed pressures and concentrated forces, and on diametrically horizontal plane due to concentrated forces, shows that it is reasonable to propose the tensile stress at the center of the particle at the point of failure as a tensile strength of the particle. Moreover, the tensile strength is a function of the Poisson's ratio of the material. As the state of stress along the z-axis in an irregular specimen tends to be similar to that in a spherical particle compressed diametrically with the same force, this tensile strength has some validity for irregular particles as well. Therefore, it can be proposed as the tensile strength for brittle materials generally. The effect of Poisson's ratio on the tensile strength is discussed.

• 대한수학교육학회지:수학교육학연구
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• 제8권2호
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• pp.495-507
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• 1998

This article intends to review what problems the terms in calculus have and how those problems are caused. For this purpose We make examinations on the considerations in the analysis of mathematical terminology, which includes the problems of general and technical terms, the meaning and the boundary of words, their consistency, the name and meaning, concept and their concept images, translations and qwerty effects. And in chapter 3, We analyse the textbook which are currently used, through which I was able to find out that the terms in calculus have some problems, In other words, the key terms such as "differentiable", "differential coefficient", "differential" have their roots in the term "differential" but the term "derived function" is very distinct from other terms and thus obstructs the consistency of terms. And the central term "differential" is being used without clear definition. In particular, the fact that "differential", when used in its arbitrary definition, has the image of "splitting minutely" can be an obstacle to understanding the exact concepts of calculus. In chapter 4, We make a review on the history of calculus and the term "differential" currently used in modern mathematics so that I can identify the origin of the problem connected with the usage of the term "differential". We should recognize the specified problems and its causes and keep their instructional implications in mind. Furthermore, following researches and discussions should be made on whether the terminology system of calculus should be reestablished and how the reestablishment should be made.e terminology system of calculus should be reestablished and how the reestablishment should be made.

• 대한화학회지
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• 제21권1호
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• pp.23-31
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• 1977

Octahedral symmetry 를 지닌 리간드에 의한 영향 아래있는 하나의 d전자를 갖는 금속 착물을 대상으로, 결정장 분리계수 10Dq를 결정장이론에 의하여 이론적으로 계산하였다. 점전하 모형을 쓰되, Shull-Lowdin 함수를 사용하여 배치간 작용을 고려하고, Integral Hellmann-Feynman Theorem을 써서 고차섭동의 영향을 추출하였다. 고차섭동의 영향이 일차섭동의 약 $50{\%}$가 됨을 알았다. Octahedral potential에 의해 3d 함수의 각 성분의 변화가 없고, $E_g\;와\;T_{2g}$상태에서, 동경성분의 변화가 일정하므로 10Dq는 유일한 파라미터로 남을 것이라는 결론을 얻었다.

• 한국표면공학회지
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• 제53권5호
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• pp.232-240
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• 2020

Cu₂O films as a photocathode for photoelectrochemical water splitting were potentiostatically deposited on FTO glasses. The morphology and composition of the electrodeposited Cu₂O films were adjusted by the applied potentials. The potential-dependent grain size of Cu₂O films was characterized by XRD and SEM analysis. Photoelectrochemical properties of the fabricated Cu₂O photocathodes were investigated with photocurrents as a function of potentials under 1 sun condition of 100mW/㎠. Photocurrents of the electrodeposited Cu₂O films were controlled with the tailored surface morphologies of Cu₂O photocathodes.

• 한국가시화정보학회지
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• 제20권3호
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• pp.74-85
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• 2022

We propose a Cubic-Interpolated Pseudo-Particle Lattice Boltzmann method (CIP-LBM) for the convection-diffusion equation (CDE) based on the Bhatnagar-Gross-Krook (BGK) scheme equation. The CIP-LBM relies on an accurate numerical lattice equilibrium particle distribution function on the advection term and the use of a splitting technique to solve the Lattice Boltzmann equation. Different schemes of lattice spaces such as D1Q3, D2Q5, and D2Q9 have been used for simulating a variety of problems described by the CDE. All simulations were carried out using the BGK model, although another LB scheme based on a collision term like two-relation time or multi-relaxation time can be easily applied. To show quantitative agreement, the results of the proposed model are compared with an analytical solution.