Liquid Metal Embrittlement of Resistance Spot Welded 1180 TRIP Steel: Effect of Electrode Force on Cracking Behavior

Du‑Youl Choi,Ashutosh Sharma,Sang‑Ho Uhm,Jae Pil Jung 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1

Liquid metal embrittlement (LME) caused cracking of Galvanized transformation induced plasticity steels was investigatedduring resistance spot welding (RSW). Effect of electrode force (3–5 kN) for a weld time of 400, and 800 ms on crack resistanceof TRIP steel was examined in relation to LME phenomenon. The microstructural characteristics of spot weld jointsand LME cracking tendency were investigated using dye penetration tests, optical microscopy, scanning electron microscopytogether with energy dispersive X-ray spectroscopy. It was found that as the electrode force increases, the crack size decreasesdue to a fast increase in crack tip temperature which rises further with more holding time up to 800 ms in high temperaturezone. Least amount of crack size was observed at 5 kN electrode force and 400 ms of welding time. Finally, the experimentalresults have also been simulated by finite element modeling (FEM) to find suitable mechanism of crack formation, and acombination of 4 kN and 400 ms was suggested for the crack free and less thermal deformation in the spot welded TRIP steel.

공공분야 전자상거래 추진에서 나타난 정보기술 관점의 사례분석 연구

이재두,김정태,김병초 한국경영과학회 2002 한국경영과학회 학술대회논문집 Vol.- No.1(1)

본 연구에서는 국가 및 공공부문에서 전자상거래를 추진할 때 정보기술과 관련되어 발생하는 공통되는 문제를 도출하여, 향후 전자상거래를 추진할 때 시사점 및 교훈을 제시하고, 전자상거래를 추진하려고 하는 조직의 시행착오 최소화 및 이와 관련된 위험요소를 식별하기 위한 아이디어를 찾고자 한다. 이를 위해 공공에서 추진한 전자상거래와 관련된 정보화사업의 사례와 정보기술관점의 점검활동인 정보시스템감리의 결과를 기술적 관점에서 분석한다. 그리고 공공부문에서의 전자상거래관련 정보화사업을 추진을 할 때 기술적인 관점에서 유의해야 할 시사점을 도출하고, 향후 국가 정보화 사업의 효율성 및 효과성을 제고를 할 수 있는 방법을 제시 하고자 한다.

요 배양검사에서 양성인 어린이의 임상적 분석

최두영,김재일,김동적 圓光大學校 醫科學硏究所 1997 圓光醫科學 Vol.13 No.1-2

A clinical analysis was done for the 110 pediatric patients with positive urine culture during Jun. 1992 to Dec. 1995 retrospectively. The patients who were hospitalized were classified group Ⅰ, under 29 days of age, and group Ⅱ, number of 29 days of age to 15 years old, respectively. The diagnostic criteria of urinary tract infection were first, the numbers of colonies of single organism isolated from clean urine collected by catheter was over 100,000/㎖. second, the numbers of colonies of single organism isolated from by supurapubic aspiration was over 1,000/㎖. third, two or more cultures yielding more than 100,000 colonies of a single identical organism from obtained by urine bag after aseptic preparation of genitalia. The results are summarized as follows : 1. The mean age of group Ⅰ was 9 days and 2.7 years in group Ⅱ. 2. Male to female ratio of group Ⅰ was 2.4 : 1 and 1.7 :1 in group Ⅱ. 3. The most common symptom was fever in both group Ⅰ(37%) and group Ⅱ(62%). 4. The pyuria(>5WBC/hpf) was detected in 21 cases(51%) of group Ⅰ and 32 cases(46%) of group Ⅱ. 5. The bacteriuria was detected in 22 cases(55%) of group Ⅰ and 25 cases(36%) in group Ⅱ. 6. The most commonly cultured bacterial species were E. coli in both group. 7. The most sensitive antibiotics for cultured E.coli was amikin.

左金丸이 腸運動 및 胃液分泌에 미치는 影響

崔斗鎬,文九,文錫哉 圓光大學校 韓醫學硏究所 1993 원광한의학 Vol.3 No.1

Effects of Joakeumwhan(左金丸) extract on the gastrointestinal tract were investigated in rabbits and rats. Treatment of Joakeumwhan extract caused an increase of contractile response of the isolated rabbit ileum. Generally the magnitude of increase was related to the dose of Joakeumwhan extract. The contracting effect of Joakeumwhan extract was not changed by pretreatment of Atropine. The contracting effect of Joakeumwhan extract was inhibited by pretreatment of Pheniramin maleate. The contracting effect of Joakeumwhan extract was inhibited by pretreatment of Cyproheptadine. The contractile response of the isolated lieum was reduced by retreatment of Joakeumwhan extract. The gastric secretion of rat was increased by treatment of Joakeumwhan extract. The gastric acidity of rat was not changed by treatment of Joakeumwhan extract.

스포츠시설 이용빈도에 미치는 요인 분석

조재기,김경두 東亞大學校附設스포츠科學硏究所 1996 스포츠科學硏究論文集 Vol.14 No.-

This research try to find out the motivation, the reason the relationship of facilities good impression etc of sports users who use swimming centre golf centre, Bowling centre, fitness centre, Aerobics centre in Taegu and near by. These factors present how to effect of using frequency of facilities. The result of this study follow; 1. In the frequency of facilities - The highest age are under 20 which is user's rate. Monthly income - under 1,5000,000. The time of use - walk. The kind of sport - fitness. The reason - to manage for beauty 2. The effect of using factors ; Reporter of sports. The reason of using facility. The time of using facility. Monthly side expenditure for sports activity. Age, Monthly income. Monthly income. Monthly pure expenditure for sports activity. The time for stay in centre.

자연환경방사선에 의한 피폭선량(유효선량당량)의 종합적 해석연구

전재식,채하석,이병영,김현창,이동준,김도성,엄두하 충남대학교 기초과학연구소 1990 연구논문집 Vol.10 No.-

자연환경방사선의 세 가지 주요 요소인 지각방사선, 우주선 전리성분 및 라돈과 그 자핵종이 주는 선량을 측정, 해석하였는 바 18개월간에 걸쳐 대전, 수원, 경산 지역에 대하여 수행하고 이를 종합하여 유효선량당량으로 평가하였다. 지각방사선과 우주선 전리성분 측정을 위하여 3"∮×3" Nal(Tl) 섬광검출기와 휴대형 다중파고분석기를 이용한 감마선 분광분석 및 ^7LiF PTEE disk TLD에 의한 적산선량측정을 병행하였고, 공기중 라돈농도의 측정은 CR-39 고체비적검출기를 내장한 라돈컵을 설계제작하여 사용하였으며 비적수 라돈농도 교정인자는 스웨덴 국립방사선 방호연구소의 표준 라돈 챔버내에서 조사하여 결정하였다. 세 지역의 가연방사선에 의한 유효선량당량에는 약간의 수치적 차이는 있었으나 본질적 차이는 찾아볼 수 없었으며 지역 측정치의 분산가중 평균치는 지각방사선 (463±3)uSvㆍy^-1[(52.9±0.3)nSvㆍh^-1], 우주선 전리성분 (287±15)uSvㆍy^-1[(32.8±1.7)nSvㆍy^-1]로 외부 피폭이 (775±9)uSvㆍy^-1[(88.5±1.0)nSvㆍy^-1]였으며 라돈과 그 자핵종에 의한 내부피폭은 (1973±298)uSvㆍy^-1[(225.2±34.0)nSvㆍy^-1]였다. 따라서 자연황경방사선에 의한 여간 총 선량당량은 (2762±296)uSvㆍy^-1[(315.3±34.0)nSvㆍh^-1]로 평가되었는데 이 값들은 UN보고서^(11)에 나온 “정상적 자연방사선 지역”의 값과 비교할 만한 타당한 값으로 나타났다. Assessment of effective dose equivalent from natural environmental radiation that consists of terrestrial gamma­ray, ionizing component of cosmic­ray and alpha­rays of atmospheric radon and its decay products has been carried out for 18 months in Daejeon, Suwon and Kyungsan areas. A 3"∮×3"cylindrical Nal(Ti) scintillation detector in association with portable multichannel analyser and ^7LiF PTFE disk TLDs were used for the measurement of terrestrial gamma­ray and cosmic­ray ionizing component, while self­designed radon­cups with CR-39 SSNTD attached to the inside bottom were used for the integral measurement of at­mospheric radon concentration. Determination of calibration factor for converting track density of CR-39 detector to radon concentration was made by irradiation of radon­cups in the standard radon chamber of Swedish National Institute of Radiation Protection. Although resultant effective dose equivalents of three different measurment points show minor numerical differences, no essential discripancy between the places was found. The variance weighted means of the annual effective dose equivalents of each component of radiation from the tree places came out to be: (463±3)uSvㆍy^-1[(52.9±0.3)nSvㆍy^-1] for terrestrial gamma­ray, (287±15)uSvㆍy^-1[(32.8±1.7)nSvㆍy^-1] for ionizing component of cosmic­ray and (1973±298)uSvㆍy^-1[(225.2±34.0)nSvㆍy^-1] for internal exposure of radon and its decay products. Consequent total effective dose equivalent turned out to be (2762±298)uSvㆍy^-1[(315.3±34.0)nSvㆍy^-1], which if reasonably comparable with that appeared in UNSCEAR Report^[11]as per caput annual effective dose equivalent in “areas of normal back ground radiation.”

위키 기반 협동적 글쓰기 학습 모형 개발

김두규,박수홍,정주영,이재학 한국초등국어교육학회 2008 한국초등국어교육 Vol.37 No.-

위키는 협동하여 글쓰기를 위한 상호작용적 도구로 활용할 수 있는 웹 기반의 하이퍼텍스트 저작 시스템이다. 위키는 프로토타입 개발을 위한 동료 간의 토의와 협업 도구로 사용되고 있으며, 일반적으로 누구나 자유롭게 정보와 지식을 편집할 수 있는 지식 공간으로 웹을 기반으로 하는 동적 프로그래밍이라고 할 수 있다. 본 연구는 이러한 키의 아이디어를 바탕으로 초등학교 쓰기 학습에서 필요한 학습자들의 협력적 의사소통과 의미구성을 효율적으로 지원하는 위키의 도구적 특성과 학습자 간,학습자와 교수자 간의 시·공간적 제약을 극복할 수 있는 상호작용적 교수·학습을 구성하는 위키식 협동학습 환경으로 협동적 글쓰기를 위한 학습모형을 개발하는 것이다. 이러한 목적을 달성하기 위하여 위키 기반 협동적 글쓰기 학습 모형에 내재되어 있는 핵심 가치와 핵심 학습 활동을 분석하고, 협동적 글쓰기 학습의 핵심 학습활동을 촉진시켜 주는 지원 전략을 도출하였다. 뿐만 아니라 위키 기반 협동적 글쓰기 학습 모형의 초안을 구안하고, 전문가 검토를 통한 수정을 거쳐서 최종적인 위키 기반 협동적 글쓰기 학습 모형을 개발하였다. The purpose of this study is to develope Wiki based learning models for collaborative writing by integrating the features of Wiki to collaborative writing skills. The first research task of this study is to derive the inherent core values and learning activities from Wiki based collaborative learningmodels. Second task is to derive support strategies to promote learning activities (writing strategies, cooperative learning, blending learning) of these models. Thrd task was, based on the extracted core values, core learning activities, and support strategies, to make the draft of learning models of collaborative writing. After modifications by expert reviews, suggested the final Wiki based collaborative learning models. The methods and procedures of this study is below. First, investigated and analyzed the situation and problems by the law questionnaire surveys, and then extract key elements and learning activities from Web using case studies and previous researches of model development. Secondly, construct the daft of the learning models. Finally,revised them consistently by experts review. The result of this research provided the theoretical basis for the learning model through the analysis and research of the core values in learning models. The researcher accepted experts review after make the draft of learning models based on the core values and principles of instructional design. Finally, through the review and evaluation of the experts, the researcher presented final Wiki.based collaborative learning models in writing skills.

중소기업지원 종합정보시스템 설계 및 구현에 관한 연구

소두석,최재원,권중장 경성대학교 공학기술연구소 2002 공학기술연구지 Vol.9 No.-

본 논문에서는 지식정보의 메카라 불릴 수 있는 대학의 인적·지적 자원을 효과적으로 활용할 수 있게 하는 종합정보시스템을 최소한의 비용으로 효과적으로 구축하기 위한 시스템의 개발방법에 대해 연구하고 시스템을 설계하였다. 대학의 인적·물적·지적 자원을 효과적으로 활용할 수 있도록 하여 지역 중소기업의 기술개발과 생산성 향상을 도모할 수 있는 중소기업지원 종합정보시스템을 구축에 관해 연구하였다. 본 연구를 통해 개발한 중소기업지원 종합정보시스템은 대학의 전문기술과 인력에 대한 정보를 제공함으로써 중소기업의 기업활동에 필요한 기술과 인력을 적시에 활용 가능하도록 한다.

고 무기질 음료(π-water) 섭취시 럭비선수들의 근력, 근 지구력 및 유산소성 운동능력에 미치는 영향

손두옥,선우섭,윤우상,유재충,박영진,오종환 경희대학교 사회체육연구소 1996 體育科學論叢 Vol.- No.9

Most of elite sports player during the sports competing and trainning have used the mineral supplements to enhance on the human performance and, also a number of researcher have recommended the mineral supplements of RDA(Recommended Dietary Allowance) for them. However, It has not exactly known to the scientific interpretation and evidences of relationship between human performance and mineral. Thence, The purpose of this study was to prove whether the mineral supplements of high RDA could enhance the sport player's performance or not The subjects of this study were composed of sixteen Rugby football players(experimental group=8, high density multimineral water intake for 30days; control group=8, placebo intake)in K-H University. Both of groups were tested three times(pre=before intake, mid=after 15days supplements, post=after 30days supplments) about maximum anaerobic power(MAnp) and maximum oxygen uptake by bicycle ergometer(868), muscle strength and muscle endurance by isokinetic Cybex system(350). The statistical analysis employed this study was t-test by statistic 512+ program in machintosh computer. The result of this study were appeared that the difference in control and experimental group signified that the experimental group was high more than the control group in left knee extensor's peak torque at mid-test(P<.05), in left knee extensor's total work(%BW) at mid-test(P<.05), in left extensor's average power and average power(%BW) at mid-test(P<.05). Relative maximal oxygen uptake(㎖/LBMkg/min) in experimental group was higher than control group after 30 days the mineral supplements. These results suggest that the high density multimineral water intake should influence partially rugby football player's performance by the increment of muscle endurance and maximal oxygen uptake.

漢江流域 豪雨의 空間特性

鄭斗永,李在炯 全北大學校 1987 論文集 Vol.29 No.-

By the spectral analysis of many heavy rains' recorded data, at Han river basin, an emprical spectral density function model is presented for the spatial distribution of storm. Using the storm data which was augmented by the Stochastic correlation with it's neighbors, the multiquadric random ndom surface of total storm depth is constructed. And to separate the local components from it's regionals and find the regional charcteristics, a double Fourier analysis was applied to the total depths. The local components, storm residuals of each storm was assumed to be an homogeneous random field and investigated with it's autocorrelation function. For the practical application, isotropic was assumed which was identifyed with emprical data. Coefficients of normalized autocorrelation for all storms were shown similar appearance. Using this emprical result, an example of the radial spectral density function is presented which represents the spatial characteristics of heavyrains over Han-river basin during 1975~1983.