• 열처리공학회지
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• 제20권1호
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• pp.22-30
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• 2007

Effects of ferrite grain size on static and dynamic deformation behaviors of SCM415 stels were investigated in this study. Dynamic torsional test was conducted using torsional Kolsky bar with the strain rate of $1.6{\times}10^3/s$. Specimens with three different grain size of ferrite, $4.6{\mu}m$, $11{\mu}m$, $35.5{\mu}m$ were used. Dimple fracture mode of the dynamic test specimens showed adiabatic shear bands on the beneath of fracture surface. Increased uniform elongation and decreased non-uniform elongation appeared as grain size of ferrite decreased in dynamic torsional test. However, shear strength was independent on grain size of ferrite.

• 대한기계학회논문집B
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• 제23권10호
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• pp.1320-1326
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• 1999

Since it is not possible to generate spatially uniform particle distribution at low pressures in which in-situ particle monitors(ISPMs) are normally operated, it is of interest to investigate the response of an ISPM to particle beams at low pressures. The purpose of this study is to develop technique that can control the size of particle beams. In this study, particle beams were generated at low pressures by using identical aerodynamic lenses, and their shape and size were visualized by collecting uniform sized methylene blue aerosol particles on a filter media. It was found that the size of particle beams depends on the number of lens, the distance between lenses, and the downstream distance from the final lens. The size of particle beams decreases with increasing distance between lenses, and increases with increasing downstream distance from the final lens. The experimental results obtained in this work will be used to investigate performance of an ISPM at low pressures.

• 대한기계학회논문집
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• 제16권12호
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• pp.2376-2384
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• 1992

본 연구에서는 액적들의 분포상태가 비균일 분포 즉 비균일 액적크기 및 수밀 도 분포를 갖는 액적군에 대하여 집단점화 현상을 이론적인 해석을 통하여 규명한다. 이를 위하여 분사직후부터 점화순간까지의 과정 즉, 액적의 온도상승-증발-혼합기 형 성-반응의 진행-점화의 과정에 초기 액적들의 크기 및 수밀도 분포상태와 기체상의 조 건들이 중요 제변수들, 즉 온도, 속도, 성분질량농도 및 액적의 크기 분포등에 미치는 영향 등은 물론 액적군의 증발특성, 점화특성 등을 이론적 모델을 구성하여 해석한다. 결과들은 현재 사용되고 있는 집단연소 모델의 초기조건으로 사용하며, 액적들의 분포 상태에 따른 점화시의 액적군의 상태 및 점화 특성은 보다 향상된 연소시스템의 운전 및 설계에 분사조건으로서 활용될 것이 기대된다.

• 한국의류학회지
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• 제46권5호
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• pp.910-926
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• 2022

Suitability for the human body, freedom to move and thermal insulation are important design considerations in military clothing. This study investigates the performance and wearer-satisfaction of the functional inner winter uniform currently used in Korea; it is hoped that our data can inform the development of a future version. Interviews were conducted, in which the participants suggested various improvements. The uniforms were mainly worn for guard duty or as daily attire in cold weather. The participants chose how many layers to wear according to the current situation, rather than sticking to the layering recommended in the manual. Layering choices did not significantly affect combat efficiency but were found to affect wearers' comfort. Wearers' satisfaction was found to depend on the convenience of the clothing, whether it was in the appropriate size, freedom to move and thermal insulation. Also, this study suggests a problem with the current size system, as the analysis of size distribution, across all sizes, the range of current production is insufficient to cover the demand.

• 한국화재소방학회논문지
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• 제11권3호
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• pp.15-23
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• 1997

In this study, the alumina for gas sensor was prepared by anodic oxidation. It was stable thermally and chemically, and pore diameter and pore distribution was uniform. And the shape of pore was cylinderical. The aluminum plate was carried out by the thermal oxidation, chemical polishing and electropolishing pretreatment. The pore diameter, pore size distribution, pore density and thickness of alumina was observed with the change of reaction temperature, electrolyte concentration and current density. As a results, It was able to use for carrier because alumina which was prepared by anodic oxidationhas uniform pore size distribution.

• 한국의류산업학회지
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• 제11권5호
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• pp.753-763
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• 2009

The purpose of this study was to investigate the wearing situation and satisfaction of school uniforms with the middle and high school boys and girls, who have been in uniforms for one or more years. The subjects for the survey were a total of 560 from the 2nd and the 3rd grade of the middle school, and the 1st and the 2nd grade of the high school. The survey was performed with the questionnaire of 60 questions; 36 questions related to the actual status, such as the purchase, size, repair, and design of a school uniform, and 24 questions related to satisfaction. The results were as follows; 1. Regarding the school uniform purchase, middle school students attached importance to famous brand, while high school students valued design above everything else. The students confused with the school uniform sizing systems were 82.1 % and 72.5 % in middle and high school students. 2. 43% of middle school students and 34% of high school students had experiences of repairing their school uniforms. Regarding the reason for repair, the size misfit was the highest. Boys preferred a single breasted boxy jacket with middle hip line length, and straight trousers, and girls preferred a fitted jacket of waist line length, and flare skirt of the knee line length. 3. School uniform satisfaction score showed that students were not satisfied with their school uniforms so much. Middle school students had significantly lower satisfaction about the design and psychological protection than high school students. Even though high school students showed lower satisfaction about the price and the care of school uniforms, there were no significant differences between them.

• 한국컴퓨터정보학회논문지
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• 제25권10호
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• pp.103-113
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• 2020

본 연구는 사이즈코리아의 제7차 인체치수조사 자료 중 16-18세 고등학교 남학생 데이터를 사용하여 맞음새가 우수한 교복 셔츠를 개발하기 위하여 상반신 관련 치수를 분석하여 상반신 체형을 분류하고 체형유형별 특성을 파악하고자 하였다. 이를 통해 교복셔츠 개발에 필요한 기초자료를 얻고자 하였다. 자료분석에는 SPSS Ver. 26.0 프로그램을 사용하였다. 고등학교 남학생은 높이항목은 연령별로 유의미한 차이가 없었으나 너비, 두께, 길이, 둘레, 어깨경사각, 몸무게 항목에서는 연령별로 유의미한 차이가 나타났다. 상반신 체형은 어깨길이가 길고 상반신 둘레와 너비가 작은 '긴 어깨 마른 체형', 상반신길이가 길고 상반신 둘레와 너비가 큰 '긴 상체 비만 체형', 어깨길이가 짧고 상반신 두께와 너비가 중간인 짧은 어깨 보통 체형, 어깨길이가 길고 둘레와 너비는 중간 정도인 '긴 어깨 보통 체형' 등 4개로 유형화되었다. 본 연구를 통해 추출된 사이즈 자료를 바탕으로 패턴 개발 및 사이즈 체계 구축을 통해 실질적인 맞음새가 우수한 교복 셔츠 개발이 필요할 것으로 생각된다.

• 한국수자원학회논문집
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• 제37권5호
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• pp.387-395
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• 2004

본 논문에서는 하상변동 및 유사입자의 시간적 공간적 분포를 동시에 모의할 수 있는 2차원 수치모형을 제시하였다. 사행수로의 하상변동은 만곡부의 외측에서는 하상이 세굴되고 훨씬 더 거친 입경의 재료로 구성되며, 만곡부의 내측에서는 하상이 상승하고, 세립토로 구성되었다. 또한 사행하천에서 흐름의 방향에 대한 입자분포 과정은 상류의 변곡점에서 시작하여, 하류 변곡점에서 마치게 되는 것을 보여주었다. 하천의 경계가 불규칙하고 복잡한 하천에서는 혼합사호 형성된 하천에서보다 균일사로 이루어진 하천에서 하상이 깊게 세굴되는 현상을 보여준다. 혼합사로 이루어진 하천에서의 공간적 입도 분포는 사행하천에서와 마찬가지로 하상이 퇴적되는 사행의 내측에서는 세립토로 구성되고 하상이 세굴되는 외측에서는 굵은 입자로 구성되는 것을 보여주었으며, 하천 폭이 좁은 부분에서는 하상의 세출 및 하상재료가 굵게 변화되는 것을 보여주었다.

• Journal of Welding and Joining
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• 제12권1호
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• pp.59-72
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• 1994

This paper presents an on-line quality monitoring and control method to obtain a uniform weld quality in gas metal arc welding (GMAW) processes. The geometrical parameters of the weld pool such as the top bead width and the penetration depth plus half back width are utilized to assess the integrity of the weld quality. Since a good quality weld is characterized by a relatively high depth-to-width ratio in its dimensions, the second geometrical parameter is regulated to a desired one. The monitoring variables are the surface temperatures measured at various points on the top surface of the weldment which are strongly related to the formation of the weld pool The relationship between the measured temperatures and the weld pool size is implemented on the multilayer perceptrons which are powerful for realization of complex mapping characteristics through training by samples. For on-line quality monitoring and control, it is prerequisite to estimate the weld pool sizes in the region of transient states. For this purpose, the time history of the surface temperatures is used as the input to the neural estimator. The control purpose is to obtain a uniform weld quality. In this research, the weld pool size is directly regulated to a desired one. The proposed controller is composed of a neural pool size estimator, a neural feedforward controller and a conventional feedback controller. The pool size estimator predicts the weld pool size under growing. The feedforward controller compensates for the nonlinear characteristics of the welding process. A series of simulation studies shows that the proposed control method improves the overall system response in the presence of changes in torch travel speed during GMA welding and guarantees the uniform weld quality.

• 한국분말재료학회지
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• 제10권5호
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• pp.318-324
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• 2003

The nano-scale crystallite sizes of uranium oxide powders in simulated spent fuel were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed $UO_2$ and fission product powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The non-uniform strain, stacking fault and twin probability were measured using the information from the diffraction pattern. The realistic crystallite size could be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin.