• 한국정밀공학회지
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• 제19권2호
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• pp.106-113
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• 2002

Stencil is used normally as a mask for seeder pasting on pad of PCB. The objective of this study is to develop stencil cutting system and determine optimal conditions which make good-quality stencil by using a Nd:YAG laser. The effects of process parameters such as laser power, type of mask, gas pressure, cutting speed and pulse width old the cut edge quality were investigated. In order to analyse fille cut surface characteristics(roughness, kerf width, dross) optical microscopy, SEM photography and roughness test were used. As a result, the optimal conditions of process parameters were determined, and the practical feasibility of the proposed system is also examined by using a commercial Gerber file for PCB stencil manufacturing.

• 한국정밀공학회지
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• 제4권4호
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• pp.84-92
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• 1987

To investigate the influence of the cutting pressure on the laser cutting quality, an expermental facility was constructed which can measure the cutting pressure distribution for various cutting conditions. Flow visualization was performed using the Schlieren photography and the pressure acting on the workpiece surface was measured, corresponding to the important process variables such as the kind of assist gas, nozzle pressure, distance between the nozzle exit and the workpiece surface, and the presence of the secondary nozzle. The cutting pressure acting on the workpiece was largely influenced by the nozzle pressure and nozzle-workpiece distance. The secondary nozzle which is used to raise the effective working pressure had its obvious role only when the angle between it and the main nozzle was small and when the distance between the nozzle exit and the workpiece surface was large.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.29-39
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• 2010

By understanding the construction process of sea dikes and the current state of the thickness and speed of fluid in the bottom layer protection work of final closure gaps, a construction method applicable for the blocking of bottom layer work will be selected. The three construction methods selected will be tested in site through various methods, and the reinforcement of bottom layer protection and impervious effect will be verified. The verification results are as follows: 1) The overall riprap layer were 0.5~1.0m thicker than planned so that the grouting depth and grout input amount increased 2) The applied construction methods permeability of riprap layers were improved from $\alpha{\times}10^{-2}cm/s$ before the construction to $\alpha{\times}10^{-4}cm/s$ after construction. 3) The results of core extraction in order to grossly verify the hardening time and durability allowed the identification of grout injection effect. The amount of filling of the injection was difficult to judge because the slime in many areas made the reading of borehole photography difficult.

• 한국실내디자인학회논문집
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• 제16권2호
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• pp.347-356
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• 2007

The concept of time-space to be seen in the modem society has complex features at the points of scientific, philosophical, artistic, religious point of view. It has been brought up at a points of neo centric religious, philosophical view and then after, phenomenal approach and scientific approach were rendered through Newton and Einstein and so many scholar approaches affected the artistic field significantly. With such visual expression, it has affected the paintings for a long time till the 19th century, and then has affected various fields such as photography, film, video, computer, architecture and has currently affected the various space expressive of our daily lives and virtual space of digital. This study is to extract a visual and expressionistic characteristic through historical examination and multi-scholar analysis of time-space concept. Especially, by expanding the previous time and space concept, experimental cases and expressionistic characteristics has come up on the media art that offers various experience and by analyzing the expressionistic characteristics of the time-space concept expressed in media art, it is to extract the basic factors for the diversity of space experience.

• 한국농촌건축학회논문집
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• 제13권4호
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• pp.83-90
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• 2011

The purpose of this study is to grasp the color situation of buildings on Urban Street, through the color image evaluation to research primary factors have an effect on color image preferences. A scope of this study is district of Sang Mu in Gwangju Metropolitan City. A method of study put out evaluation model after BIB test by photography, spot color. And performed Factorial Design, Multiple Regression Analysis through SD questionnaire. The result of this study show that color situation exceedingly used YR predominates, support, stress color, in the second place used predominate, support color is B, stress color is R. Luminosity showed middle luminosity 4.1~7.0, low freshness distribution. Color image was evaluated modern and cold image and appeared affirmative aspect clean, order, neat image and showed negative aspect stiff, flat image. And 'comfortableness', 'unification' had an effect on color image preferences The result of this study showed that color plan need to improve comfortableness, unification bring control into line color at building color image of urban street.

• 한국생활과학회지
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• 제22권6호
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• pp.571-586
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• 2013

The purpose of this study was to examine educational meanings of snack and lunch time of 4-year-old children and their teachers in a kindergarten class. The study was done in the Class of 4-year-old children in S Kindergarten located in Songpa-gu, Seoul. And 30 children of this class, Teacher A who is the teacher in charge of the Class, and Teacher B who is the researcher and teacher in charge of it participated in it. The study was carried out by the ethnography method and data collection was done through participation observation, interviews, video and voice recording, and data collection of photography shooting. The results are as follow: First, the children had private conversations, shared their cultures, deepened and expanded their existing concepts, expressed their emotions and relieved their tension, and strengthened relations with friends during the snack and lunch time. Second, the teachers promoted conversation and communication, gave the opportunity that the children can set the lunch table by themselves and tried to make the snack and lunch time with the children by discussing what they are how they are operated with them together. In conclusion, the snack and lunch time can be more meaningful time for children when there are proper educational plans and support of teachers which are considered children's viewpoints.

• 한국인쇄학회지
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• 제15권1호
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• pp.31-40
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• 1997

The objectives of color reproduction in printing, photography, and digital hard-copy is an important problem. The Color is obsorved differently from illumination an obsorvation condition, and varied according to individual taste. Generally, the color reproduction system is designed with colorimetric color reproduction method. But the color gamut of the color reproduction system is different each other and the one device has nonlinear relationalship between the other. By these reason, to predict the reproduced color based on linear color transform method is difficult. Some methods of non-linear color transform by neural network was proposed. These method was theoretical useful and valid to transform from CIE color to device color. But more studies were needed to realize the non-linear color transform system. In this paper, we described a method to realize the non-linear color transform system by neural network. The optimum structure of the non-linear color transform system was found out. The structure of descrived system has four layer( input, output and two hidden layers.) Input and output layer have 3 units, and a hidden layer has 27 units. We trained 216 color-samples, and estimated the realized color transform system by 1115 color-samples. The average color difference between original color samples and transformed color samples was 2.54.

• 한국추진공학회지
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• 제19권4호
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• pp.45-51
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• 2015

정상초음파의 영향을 받는 메탄-공기 예혼합화염의 주파수-당량비 상관도 분석을 위한 실험적 연구가 수행되었다. 슐리렌가시화기법을 이용하여 예혼합화염의 전파영상을 획득하였으며, 영상 후처리를 통해 화염의 구조변이 및 전파거동을 면밀히 관찰하였다. 정상초음파가 개재할 때, 화염선단과 기연부에서 구조적 변이와 연소반응 촉진으로 인한 화염의 전파속도의 증가를 가져온다는 사실에 더하여, 초음파 구동주파수와 당량비에 대한 화염거동의 종속성을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.258-262
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• 2011

실험용 분젠 연소기를 사용하여 예혼합된 메탄-산소 층류화염전파속도를 연구하였다. 이를 위해 $CH^*$ 자발광 측정기법과 슐리렌 사진술이 사용되었다. 실험결과는 CHEMKIN 3.7을 이용한 수치해석 결과와 비교하였다. 층류화염전파속도를 측정하기 위하여 층류여역 내에서 전체 당량비는 0.5에서 2.0까지 조절하였다. 동축 화염에서 화염전파속도는 각도측정법을 사용하였으며 슐리렌 사진에서는 3.1 m/s로 $CH^*$ 자발광 사진에서는 2.9 m/s로 측정되었다.

• 한방안이비인후피부과학회지
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• 제23권2호
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• pp.186-195
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• 2010

Objective : This study was performed to prove the effect of the oriental medical treatments like acupuncture, moxibustion, herbal medicine on macular edema resulted from branch retinal vein occlusion which could lead to terrible result like permanent visual loss at worst. Methods : The patient was treated 62 times, from July 15th, 2009 through May 12th, 2010. We used fundus photography and Dr. Hann's standard test chart for 5m to examinate the patient's eyesight. We used acupuncture, electropuncture, moxibustion and herbal medicine to treat the patient. We considered visual field, scotoma, metamorphopsia and vitreous floater to measure the effect of treatment. Results : After about 10 months of treatment, the eyesight of Rt eye was improved from 0.8 to 0.9, Lt. eye from zero to 0.3. The visual field turbidity were absolutely cleared. The scotomas in Lt. eye were reduced from 5 to 2. The metamorphopsia were improved. The vitreous floaters in Rt. eye were decreased from 5~6 to 1~2. Conclusion : These results show that the oriental medical treatment can be conservative measure to the macular edema resulted from branch retinal vein occlusion.