• Bulletin of the Society of Naval Architects of Korea
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• v.12 no.1
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• pp.59-75
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• 1975

The thermal stresses due to a heat source moving crosswise on a finite breadth plate, which is much more like to the practical welding problems, were studied. The temperature distributions in the plate were obtained analytically using the mirror image method, and the thermal stresses were calculated by the finite-difference method. Some numerical calculations for temperature distributions and thermal stresses were performed. The temperature distributions were also obtained by experiment. It was found that the theory was in good agreement with the result of experiment, and the calculated thermal stresses were resonable.

• Journal of Integrative Natural Science
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• v.6 no.2
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• pp.82-86
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• 2013

This paper describes a method for the preparation of porous polymethylmethacrylate showing optical reflectivity from the porous silicon template. A porous polymethylmethacrylate showing optical reflectivity was prepared by replicating porous silicon template which was obtained by applying a computer-generated periodic square current density and resulted in a mirror with high reflectivity in a specific narrow spectral region. A porous polymethylmethacrylate showing an excellent reflectivity was successfully obtained by dissolving the Porous silicon template from the porous polymethylmethacrylate composite film. A porous polymethylmethacrylate exhibited a sharp reflection resonance in the reflectivity spectrum. Surface image of the porous polymethylmethacrylate indicated that the surface of the porous polymethylmethacrylate film had a porous structure. These porous polymethylmethacrylate films in aqueous solutions were stable for several days without any degradation.

• Journal of Chest Surgery
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• v.28 no.7
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• pp.698-703
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• 1995

Dextrocardia means right-sided position of the heart in the chest irrespective of the cause. For the absolute diagnosis of the dextrocardia, the segmental analysis of heart is necessary. Once the segmental analysis of the dextrocardia is made, it is often relatively easy to identify the presence of any associated defects based on conventional methods including physical examination, EKG, echocardiography, and angiocardiography. Two cases of dextrocardia with congenital heart disease were treated surgically.A eleven - months old boy was operated under diagnosis of ASD, VSD, and bilateral SVC with mirror - image dextrocardia {I,L,I} by primary closure of ASD and VSD.A twenty-four months old girl was operated under diagnosis of ASD, VSD, and PS with corrected TGA {I,D,D} by primary closure of ASD, VSD and dilatation of pulmonary stenosis. Both of them were discharged healthily after operation.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.613-620
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• 1992

The solvent-dependent photophysical properties of 2-biphenylcarboxylic acid (2BPCA) and 4-biphenylcarboxylic acid(4BPCA), which have a pre-twisted conformation in the ground state, have been investigated. The fluorescence spectra of 4BPCA show vibrational structure with a non-mirror image to the absorption spectra in nonpolar solvent while those of 2BPCA show no structure even in nonpolar solvents. As the solvent polarity increases, the fluorescence spectra become diffuse and broad with a strong red shift resulting in the large Stokes shift. The large fluorescence Stokes shift of BPCA's in polar solvent is also partially due to an intramolecular charge transfer (ICT) interaction in the excited state, as demonstrated by the large dipole moment in the excited state (7.6-10.6 D). The fluorescence decay behaviors of BPCA's (decay-times and their pre-exponential factors) also depend on solvent polarity in agreement with the solvent-dependent properties of the steady-state fluorecence. The data have been discussed in terms of change in the excited-state potential energy surface with respect to change of the dihedral angle of biphenyl moiety.

• International Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.8-15
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• 2018

For small earth observation satellites, alignment between the optical components is important for precise observation. However, satellite cameras are structurally subject to misalignment in the launch environment where vibration excitations and impacts apply, and in space environments where zero gravity, vacuum, radiant heat and degassing occur. All of these variables can cause misalignment among the optical components. The misalignment among optical components results in degradation of image quality, and a re-alignment process is needed to compensate for the misalignment. This process of re-alignment between optical components is referred to as a refocusing process. In this paper, we proposed a 3 - axis focusing mechanism to perform the refocusing process. This mechanism is attached to the back of the secondary mirror and consists of three piezoelectric inertia-friction actuators to compensate the x-axis, y-axis tilt, and de-space through three-axis motion. The fabricated focus mechanism demonstrated excellent servo performance by experimenting with PD servo control.

• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.308-313
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• 1998

A thermally irreversible photochromic system, 2,3-bis(2,4,5-trimethyl-3-thienyl)maleic anhydride (MTMA), has been studied by semi-empirical molecular orbital methods. There are one pair of stable conformations for the closed-ring form and three pairs for the open-ring form, each pair consisting of two mirror-image conformations. Interconversion between the parallel and anti-parallel conformations of the open-ring form is restricted due to high energy barriers. Only the anti-parallel conformation appears to be responsible for photochromic cyclization. Thermostability of the compound is attributed to an avoided crossing at high energy in the ground states of the isomers, whereas the photoreactivity can be explained by the mutually connected excited singlet (S1) states of the isomers, forming a double well potential with a low energy barrier. The large solvent effects can be partly explained with the low dipole moment of the anti-parallel conformation of MTMA in the S1 state. The large variation of quantum efficiency suggests that excess vibronic energy can be utilized to provide the activation energy for the photochromic reaction.

• Annual Conference of KIPS
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• 2021.11a
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• pp.170-172
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• 2021

현재 일상색활에서 다양한 사물들에 IT 기술이 접목되고 있다. 그 중 대표적인 제품으로 스마트미러가 있다. 스마트미러는 높은 접근성을 이용하여 사용자에게 일기예보, 뉴스피드, 캘린더, 개인맞춤정보 등 일상생활에 밀접한 다양한 정보를 제공한다. 본 논문은 영상처리 기반 얼굴인식을 이용한 스마트 미러 시스템을 제안한다. 그리고 실제 프로토타입을 제작함으로써 실제 사용가능 여부를 판단하였다.

• Clinical Pain
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• v.18 no.2
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• pp.133-137
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• 2019

The long-term prognosis of complex regional pain syndrome is difficult to predict because of its unclear pathophysiology. The syndrome can spontaneously spread to other regions in the body. We report a case in which a complex regional pain syndrome that occurred in a 75-year-old male patient after a stroke spread to the opposite side.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.8
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• pp.868-874
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• 2014

This paper proposes a novel mapping algorithm in Omni-directional Vision SLAM based on an obstacle's feature extraction using Lucas-Kanade Optical Flow motion detection and images obtained through fish-eye lenses mounted on robots. Omni-directional image sensors have distortion problems because they use a fish-eye lens or mirror, but it is possible in real time image processing for mobile robots because it measured all information around the robot at one time. In previous Omni-Directional Vision SLAM research, feature points in corrected fisheye images were used but the proposed algorithm corrected only the feature point of the obstacle. We obtained faster processing than previous systems through this process. The core of the proposed algorithm may be summarized as follows: First, we capture instantaneous $360^{\circ}$ panoramic images around a robot through fish-eye lenses which are mounted in the bottom direction. Second, we remove the feature points of the floor surface using a histogram filter, and label the candidates of the obstacle extracted. Third, we estimate the location of obstacles based on motion vectors using LKOF. Finally, it estimates the robot position using an Extended Kalman Filter based on the obstacle position obtained by LKOF and creates a map. We will confirm the reliability of the mapping algorithm using motion estimation based on fisheye images through the comparison between maps obtained using the proposed algorithm and real maps.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.89-93
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• 2020

Complex warpage behavior of the electronic packages causes internal stress so many kinds of mechanical failure occur such as delamination or crack. Efforts to predict the warpage behavior accurately in order to prevent the decrease in yield have been approached from various aspects. For warpage prediction, silicon is generally treated as a homogeneous material, therefore it is described as showing no warpage behavior due to thermal loading. However, it was reported that warpage is actually caused by residual stress accumulated during grinding and polishing in order to make silicon wafer thinner, which make silicon wafer inhomogeneous through thickness direction. In this paper, warpage behavior of the single-side polished wafer at solder reflow temperature, the highest temperature in packaging processes, was measured using 3D digital image correlation (DIC) method. Mechanism was verified by measuring coefficient of thermal expansion (CTE) of both mirror-polished surface and rough surface.