Effects of Cooling Rate on the Microstructure and Tensile Properties of Wire-Arc Additive Manufactured Ti–6Al–4V Alloy

Hui‑Jun Yi,Jin‑Woo Kim,Young‑Lak Kim,Sangyong Shin 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

Wire-arc additive manufacturing has emerged as a technology that could replace the conventional manufacturing processof titanium alloys. However, it produces a coarse β grain, which can accumulate via several deposited materials, resulting isstrong texture and anisotropy. To investigate potential solutions, the effects of the cooling rate on the resulting microstructureand tensile properties were studied. The cooling rate of the deposited materials was adjusted by interpass temperaturecontrol. Under rapid cooling, fine α + α′ grain with a low aspect ratio were observed and tensile and hardness propertieswere also improved.

학대받는 알코올 중독자 부인을 위한 프로그램 개발에 관한 연구

김혜련,조영희 한국알코올과학회 2000 알코올과 건강행동연구 Vol.1 No.1

인터넷을 중심으로 한 ICT 기반 수업 전략

김영환,김광휘 釜山大學校 敎育硏究所 2001 敎育硏究 Vol.11 No.1

For an ideal ICT education, the development of alternative and strategies toward internet based instructions will be needs. However, the essential factor of instructions is that there should be more considerations and cares for learners, and thus more improved quality of instructions. Internet based instruction is part of those attempts. The basic condition for internet based instructions is the fulfillment of various factors for good instructions. Strategically, they are effectiveness for better instructions, efficiency between teacher’s and student’s performances, attractiveness for exiting learners’ and teachers’ interactions, and morality in means and contents. They are microscopic factors. The example of macroscopic factors is the reliance and empathy between teachers and students. A good teacher will be free from external restrictions and steadily use the internet or other ICT environments to make the best ICT based instructions.

[논문]직렬형 2배수 권선비 변압비를 이용한 HBML PWM 인버터

고희영,김철우 釜山大學校生産技術硏究所 2005 生産技術硏究所論文集 Vol.64 No.-

본 논문에서는 고조파를 저감하고 출력 파형을 개선하기 위하여 H-Bridge 인버터와 변압기 조합을 이용한 다중레벨 인버터를 구성함에 있어 변압기 출력 전압의 조합을 이용한 새로운 하이브리드형 멀티레벨 인버터를 제안한다. 제안한 다중 레벨 인버터는 THD을 저감하기 위해 변압기의 권션비가 1배,2배,4배인 3대를 사용하여 출력전압을 기존의 9 레벨에서 15 레벨로 증가 하였다. 또한 PWM 인버터 스위칭 패턴을 변경하여 스위칭 소자수를 10개에서 8개로 저감하고,변압기를 4개에서 3개로 저감할 수 있는 방법을 제안한다. 제안된 다중레벨 PWM 인버터의 전력회로 및 제어신호의 타당성을 입증하기 위해 프로토 타입 15레벨 언버터에 대하여 실험을 행하였다.

식품 기준·규격의 합리적 관리 ·운영에 관한 연구(Ⅰ) : 두부,식용유지, 전분의 분말상 원료에 관하여 Powdered marerials of Tofu, Edible oil, Starch

김희연,홍진환,박혜경,한상배,박종석,이은주,이정성,송경희,최은희,최영준,소경아,성영제,이주엽 식품의약품안전청 2000 식품의약품안전청 연보 Vol.4 No.-

본 연구는 분말상 원료(전분, 대두분)의 저장유통시 품질변화를 건전성과 안전성 측면에서 검토하여 식품의 기준 ·규격 설정f.」 합지적으로 반영하고자 하였다. 전분과 패두분의 이물을 검사하고, 2종 대두분(중국산, 미국산)을 ?0일간 IS'c와 30t에 저장하면서 성상, 수분, 산가, 과산화물가, 지방산 조성,아플라톡신 BB의 생성여부를 분석하였다. 중국산 대두분 30'』 저장군에서 50일 이후 곰팡이가 발생한 것 이외에 모든 시료에서 양호한 성상을 나타내었고, 전분과 대두닥 모든 시료에서 이물은 검출되지 않았다. 산가는 중국산과 미국산 시료간에 편차를 보여 증국산 30"C, 50일 저장시료에서 약 10배끙도 증가하였고, 과산화물가는 저장 90일후 15'E 저장군은 약 2.3배, 30'c 저장군은 3배정도 증가하였다. 대두분의 주요 지방산은 linoleic acidf18. 2), oleic acid(18 : 1), palmitic acid(16 : 0)이었으며, 3개월 저장에 따른 지방산 함량의 변화는 미미하였다. 아플라톡신 B₁은 모든 시료에서 검출되지 않았다. The objective of this study was to investigate auality changes of type raw materials(starch, soy flour) during various storage conditions. Starchflour(source of China, U.S.A) were slfred under two temperature(15'C, 30'c) forSensory evaluation, (o.reign material test, moisture content, acid value, peroxide ualue,composition, aflatorin Bi were analyzed. China soy flour(stor·ed 30'f) was contaminated by fungj on 50 days. Except for soy flour contardnated by fungi, sensory characteristics were not changed and foreign mater;als were notdetected. Acid value of China soy flour(stored at 30'C, 90 days) was about 10 times higherlevel before storage and acid value was more influenced by source(China, USA). Peroxide valuewas in proportion with the storage period slightly. The major fatty acid of soy flour waslinoleic acid(18 . 2), an(3 the change of fatty acid composition was not observed. Aflatoxlrl Blwas not detected.

Zigbee sensor 모듈에 적용 가능한 소형 PCB 안테나의 최적 설계 기법 연구

이영순,김의중,이태훈,정훈희 금오공과대학교 2006 論文集 Vol.27 No.-

본 논문에서는 소형 Zigbee sensor 모듈에 적용하기에 적합한 모듈 일체형 안테나의 최적 설계시법을 제기하고자 한다. Zigbee sensor 모듈에서 사용되는 2.45GHz 대역에 적합한 모듈 일체형 안테나를 meander slit 구조를 이용하여 최적설계 과정을 보이고, 최적화된 안테나의 설계 결과를 보였다. 그리고 기존 chip 안테나의 성능 비교를 위해 최대 동작거리 및 방사출력을 비교한 결과를 제시 하였다.

서울시 아동을 대상으로 한 주의력결핍과잉행동장애의 선별기준에 대한 연구

양영희,김재원,김예니,조수철,김붕년 大韓神經精神醫學會 2008 신경정신의학 Vol.47 No.3

Objectives : The purpose of this study is to investigate a cut-off value for screening children with ADHD in community based sample using the Korean Child Behavior Checklist (K-CBCL) and the Korean ADHD Rating Scale (K-ARS). Methods : Children aged 6 to 8 (n=661) participated in this study. The K-CBCL and the K-ARS were used as the screening instruments. Diagnoses were confirmed through the Diagnostic Interview Schedule for Children Version Ⅳ (DISC-Ⅳ). Results : Of the 189 subjects who underwent the DISC-Ⅳ, 26 subjects were diagnosed as ADHD. In the K-CBCL, scores in the attention problems, externalizing problems and total behavioral problems were positively correlated with the total score of the K-ARS. The K-ARS-Parent version (K-ARS-P) and above three scales in the K-CBCL showed significant screening validity in the ROC curve analysis. The reasonable level of sensitivity, specificity, and negative predictive value were obtained in the total scores ≥90^(th) percentile in the K-ARS-Parent and ≥60T scores in the K-CBCL attention problems. The optimal level of specificity, positive predictive value and negative predictive value were obtained when combined the K-CBCL (≥60T scores in the attention problems and ≥63T scores in the total problems) and the total scores ≥90^(th) percentile in the K-ARS-P. Conclusion : The combined use of the K-CBCL and the K-ARS-P may serve as useful screening methods for ADHD children.

담도폐쇄증 환아의 내인성 착색치아에 대한 증례보고

이창희,이상대,김영재,김정욱,한세현,이상훈 大韓小兒齒科學會 2004 大韓小兒齒科學會誌 Vol.31 No.3

담도페쇄증은 간장외 담관의 부분적이거나 완전한 파괴 또는 부재로 인한 담즙흐름의 완전한 폐쇄로 정의된다. 이 질환은대략 10,000명당 1명 정도 비율로 발생하며 여성에서 약간 높은 빈도를 보인다. 원인인자는 명확히 밝혀지지 않았으며 증상은 과빌리루빈혈증과 함께 황달, 점토색변, 지방설사, 어두운 갈색뇨, 간비대 등을 보인다. 최근의 담도폐쇄증의 치료는 간문장문합술 단독 혹은 간이식술을 병행하는 경향이다. 본 증례의 환자에서는 다양한 정도의 치아변색을 보였으며 색상은 노란색에서부터 짙은 초록색까지 다양했다. 법랑질의 저형성증이 모든 치아에 나타났고 구강위생이 좋지 않았으며 다발성 우식증을 가지고 있었다. Biliary atresia is defined as a complete obstruction of bile flow owing to destruction or absence of all or part of the extrahepatic bile ducts. This disease is occurring in approximately 1:10,000 live births and moderate pre-dominance of female is noted. The etiology of biliary atresia remained unsolved. The signs and symptoms are hyperbilirubinemia, jaundice, clay-colored stools, steatorrhea, dark yellow urine and hepatomegaly. Currently biliary atresia is best managed by hepatic portoenterostomy with or without liver transplantation. Biliary atresia patients with these cases showed staining of the teeth. The stains ranged in color from yellowish-brown to deep green. Enamel hypoplasia was all erupted teeth present. Patients had poor oral hygiene and rampant caries.

서울시내 유아기 어린이의 간식실태 및 기호도에 대한 조사 연구

유영상,김희정 동아시아식생활학회 1998 동아시아식생활학회지 Vol.8 No.1

This study estimate the amount of snack intake of 290 children from ages 3 to 6 living in Seoul, to provide some basic information for a nutrition education program for the promotion of health. Average height and weight of the children were 110.5㎝ and 19.7㎏, respectively. Their body mass index was 16.2 ㎏/㎡ and obesity index was 6.5%. Calorie intake from snacks was 294㎉, and protein, fat, carbohydrate were 11.3g, 9.3g and 40.6g, respectively. The 117(40.3%) boys prefered boiled-eggs and 112(38.6%) girls prefered fruits. The 133(45.9%) mothers of the children were in their thirties, and 123(42.4%) of them had a college degree. One hundred and thirty-one(45.2%) mothers were house keepers, and they had been givins snacks to their children 1 or 2 times daily(245, 84.5%). The daily snack budget was 1,500 won(109, 37.6%). The person who served the snack was a mother(141, 48.6%). As a result, snack intake of pre-school children showed very good but partially showed a potential problem. We hope that the results of this study can be helpful for the nutrition education program for the health and nutrition of pre-school children.

칼슘급원과 섭취수준의 노령 암컷흰쥐의 혈청 및 대퇴골에 미치는 영향

유영상,김희정,구재옥 동아시아식생활학회 1996 동아시아식생활학회지 Vol.6 No.2

This study was performed to investigate the effect of dietary dried anchovy and non-fat dried milk on serum and femur. Ten months old female rats were divieded into 6 groups(ST. A-middle, A-high, M-middle, M-high, A+M), and fed the diet containing different level of food calcium for 8 weeks. The results obtained were summarized as follow : 1. The rats' weight gain were not significantly different from the fed groups, but food intake were significantly higher or lower level in the group of A-high than the other groups. 2. Serum calcium concentration was significantly increased in the A-middle group, the M-high group were significantly decreased. Serum phosphorous contents of M-high group were increased significantly higher than ST group. The serum magnesium contents were increased significantly higher than in the A-middle group. Serum iron contents of other experimental groups were significantly higher than ST group. All experimental groups were significantly lower copper contents in serum than ST group. 3. The more rats took dried anchovy and non-fat dried milk, the longer the length of femur. But this trend is not statistically difference. In the breaking force of left femur, most of all experimental group were stronger than ST group. 4. The calcium, phosphorous contents of ash, dry, wet weight of right femur in A+M group were higher than any other groups.