• Title/Summary/Keyword: 무세정

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The Study on Micro Soldering Using Low-Residue Flux in $N_2$Atmosphere (질소 분위기에서 저잔사 플럭스를 사용한 마이크로 솔더링에 관한 연구)

  • 최명기;정재필;이창배;서창제;황선효
    • Journal of the Microelectronics and Packaging Society
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    • v.7 no.4
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    • pp.7-15
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    • 2000
  • The purpose of this work is to evaluate the solderahility and characteristics of solder joints. Bridge defect of solder joint was examined in natural atmosphere and $N_2$ condition. Consequently, wettability was excellent for each of Sn-Pb plated Cu specimen, Sn plated Cu specimen, and Cu polished in $N_2$ condition. The wetting time in $N_2$ condition was shorter than that of natural atmosphere condition, showing the decreasing values of about 0.2~0.45 seconds. The max. wetting force under the $N_2$ condition was more increasing that of natural atmosphere condition, showing the increasing values of about 1.8~2.8 N. With the result of wetting balance test, the wetting time ($t_2$) and wetting farce according to increasing amount of $N_2$ from 10 1/min to 30 1/min, the wetting time ($t_2$) was reduced about 0.25 second and wetting force was increased about 2.3 N. In non-cleaning flux, when $N_2$ gas is applied, it is compensated to decrease of wettability. In the case of using the $N_2$ gas, the wettability was improved. The reason for improving wettability is due to preventing the formation of dross. The generation rate of bridge in $N_2$ condition decreased than that of natural atmosphere, and when the specimen had a fine pitch, the rate of bridge defects was considerably decreased in $N_2$ condition, showing the decreasing rate of 25~75%.

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Comparison of Bacterial Removal Effectiveness by Different Hand Washing Methods (손세정 방법에 따른 세균 제거 효과 비교에 대한 융복합 연구)

  • Chong, Moo-Sang;Lee, Jang-Jin;Kim, Jiro
    • Journal of the Korea Convergence Society
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    • v.10 no.9
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    • pp.69-74
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    • 2019
  • The purpose of this study is to compare the efficiency of bacteria removal of three different types of hand washing methods. This study performed a convenient sampling of 30 volunteers in cross-over design. The study divided the 30 volunteers into three random groups. The three groups were asked to use antiseptic soap, alcohol-based hand disinfectant, and disposable wet wipes respectively. The result of the study showed that mean log reduction values after each had washing method were $-0.45({\pm}0.69)$ with antiseptic soap and water, $-1.19({\pm}0.52)$ with alcohol-based hand disinfectant and $-0.75({\pm}0.58)$ with disposable wet wipes. The difference was statistically significant when using alcohol-based hand disinfectant compared to the other two methods (p=0.000). According to this study, alcohol-based hand disinfectant was the most effective product based on bacteria removal for hand washing. Advantages of using alcohol-based hand disinfectant are that it is cost-effective and easy to buy, also eco-friendly. Therefore, to prevent infectious disease, providing alcohol-based hand disinfectant to every corner of the community will be very helpful.

Age Determination by Tooth Wear and Histological Analysis of Seasonal Variation of Breeding in the Big White-Toothed Shrew, Crocidura lasiura (우수리땃쥐 Crocidura lasiura의 치아 마모에 의한 연령결정과 번식의 계절적 변이의 조직학적 분석)

  • Jeong, Soon-Jeong;Yoon, Myung-Hee;Choi, Jung-Mi;Kim, Hyun-Dae;Lim, Do-Seon;Park, Jin-Ju;Choi, Baik-Dong;Jeong, Moon-Jin
    • Applied Microscopy
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    • v.40 no.1
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    • pp.37-45
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    • 2010
  • Captured wild specimens of the big white-toothed shrew, Crocidura lasiura were classified into three age classes by tooth wear and height of molars, and seasonal variations of breeding and reproductive organs were examined. Juveniles had not tooth wear in molars and height of the third molars were lower than the first and second molars, and had only non-breeding condition. Young adults had little tooth wear and the third molars reached to the first and second molars, and old adults had heavy tooth wear in molars, young adults and old adults had breeding or non-breeding condition according to the season. On the basis of histological examination, seasonal variations of breeding were confirmed that breeding condition of young and old adult males were continued from early February to early October although the breeding activity was the highest in April, that of females were continued from the end of March to October, males reached sexual maturity earlier than females. Whereas the breeding condition seems to cease for non-breeding season because of the deficiency of food resources, soil invertebrates. Young and old adult males of the breeding season had large testes with enlarged seminiferous tubules that were filled with numerous germ cells, and expanded caudal epididymides with a vast number of spermatozoa, and were more than 10.0 g in the body weight and 0.03 g in the testis and epididymis weight. The females of the breeding season were pregnant condition with 4~6 litters or had the Graafian follicles and the corpus lutea in the ovary, and were more than 9.6 g in the body weight.

Status of Health and Safety Management in Occupational Hygiene Laboratories in Korea

  • Yang, Hyukseung;Choi, Jaewook;Yoon, Seokjoon;FARR, Terry
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.17 no.1
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    • pp.53-62
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    • 2007
  • 목적: 1990년대 초반부터 시작된 우리나라의 산업 보건에 대한 사회적 관심의 증대와 시장의 요구에 따라 산업위생기관의 양적인 팽창이 이루어지긴 하였으나 실험실 관련 안전보건규정이 미비한 상태에서 추진되어 산업위생 실험실에서 다양한 유해 위험성 인자를 취급함에도 불구하고 사용되는 량이 소규모로 인해 안전보건과 관련된 사항은 대부분 간과하고 있으며, 산업위생 실험실의 안전보건관리 실태는 선진외국에 비해 상당히 낙후되어 있는 실정이다. 따라서 본 연구는 우리나라 산업위생 실험실과 관련한 안전보건관리 실태를 평가함으로써 향후 실험실의 안전보건관리 수준을 향상 시키는데 효과적인 자료로 활용하는데 기여하고자 한다. 방법: 산업위생실험실의 안전보건 실태를 파악하기 위해 설문조사를 수행하였으며, 설문은 실험실의 전반적인 안전보건, 화학물질 저장 및 용기, 가연성 및 인화성 화학물질, 가스 실린더, 의사전달, 응급처치 및 비상사태 장비, 정리정돈, 소방안전, 전기안전, 개인보호구, 흄후드 및 환기, 및 이황화탄소 취급 사례로서 12개 영역으로 구성되었다. 연구대상은 2001년 한국산업안전공단 정도관리프로그램에 참여한 기관으로서 총 대상은 119개 기관이었다. 연구기간은 2002년 7월 01일부터 8월 30일까지 약 60일 이었다. 설문은 반송봉투에 넣어 설문완성 후 연구자에게 보낼 수 있도록 배려하였으며, 1차 설문을 보낸 후 2주 후에 설문 참여를 독려하기 위해 엽서를 발송하였고, 다시 2주 후에 각 산업위생기관에 개별 전화 연락을 취하였다. 그 결과 63% (75개 기관)의 완성된 설문을 얻을 수 있었다. 설문의 총 조사항목은 79문항으로 구성되어 있으며, 산업위생실험실의 안전보건 수준을 정량적으로 평가하기 위해 안전보건 매뉴얼, 교육훈련프로그램 및 한국산업안전공단 실험실 지침서를 보유한 기관과 그렇지 않은 기관간의 차이는 선별된 67문항에 대해 각 문항에 합당하거나 적절할 경우 1점을 부여하는 방식으로 점수화하였다. 이들의 관련성을 파악하기 위하여 Microsoft-Excel 2000 프로그램을 이용하여 two-tailed t-test 분석을 실시하였다. 결과 1. 산업위생실험실 운영과 관련한 67개 항목(항목별로 각 1점 부여)에 대한 안전보건 성과지수화 (100점으로 점수 환산) 결과 안전보건 매뉴얼을 보유한 기관은 $42.98{\pm}13.36$(p<0.001)점, 교육훈련프로그램을 보유한 기관은 $50.75{\pm}14.12$(p<0.01)점, 한국산업안전공단 실험실 지침서를 보유한 기관은 $43.58{\pm}11.92$(p<0.01)점으로 그렇지 않은 기관에 비해 통계적으로 유의하게 높은 점수분포를 보였다. 2. 화학물질 보관 캐비닛이 있는 기관 중 64.8%의 기관은 화학물질을 알파벳 순으로, 27.8%는 분류 기준에 따라, 그리고 7.4%는 무작위로 보관하고 있었다. 3. 단지 8.0% (6개)의 기관만이 실험실내에 눈세정 분수(2 개), 샤워기(3개) 및 눈세정물병(3개, 2개 중복 응답 기관)과 같은 응급처치 장치 및 물품을 갖추고 있었다. 4. 89.0%의 기관이 흄후드내에 화학물질을 보관하고 있었다. 5. 물질안전보건자료, 흄후드 기록지, 비상사태 절차서 및 한국산업안전공단 실험실 지침서와 같은 문서관리는 부적절하게 관리 및 기록되고 있었다. 6. 대부분의 산업위생 실험실은 응급처치 장비, 화학물질 또는 가스용기 보관실과 같은 실험실 안전설비가 부족할 뿐만 아니라 정리정돈, 화학물질 저장 캐비닛, 안전보호구 및 흄후드와 같은 관리가 미비하였다. 결론: 이상의 결과에 근거하여 기관장은 실험실의 안전보건관리를 위하여 문서관리체계를 제공하고, 모든 실험실 종사자가 적절한 개인보호구를 착용할 수 있도록 하며, 비상 장비를 설치하고, 실험실과 관련한 적절한 규정을 제정하며, 교육훈련 프로그램을 제공하여야 한다. 또한 실험실 종사자는 실험 중 적절한 개인보호구의 착용하고, 비상장비 이용에 대한 교육훈련에 참여하며, 적절한 실험실 운영관리에 대한 책임감을 가져야 한다. 위의 권고사항 이행을 위해서 KOSHA는 KQCP 프로그램에 실험실 안전보건관리 항목을 삽입하여 주기적인 평가를 수행할 필요가 있다. 우리나라 실험실의 특성을 고려할 때 본 연구결과는 일반 실험실에도 적용될 수 있을 것으로 생각된다.

A Clinical Manifestation of Meckel's Diverticulum (Meckel 게실의 임상양상)

  • Lee, Jin Beom;Lee, Yong Soon;Yoo, Eun Sun;Kim, Hae Soon;Son, Se Jeong;Park, Eun Ae;Lee, Seung Joo;Sung, Sun Hee;Seo, Jeong Wan
    • Clinical and Experimental Pediatrics
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    • v.45 no.4
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    • pp.466-472
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    • 2002
  • Purpose : The diagnosis of Meckel's diverticulum is difficult and delayed because it presents with various clinical symptoms. We evaluated clinical, imaging and pathologic findings of Meckel's diverticulum to facilitate detection of Meckel's diverticulum in children. Methods : Review of clinical, imaging, surgical and pathological findings in 10 children aged 7 days to 14 years with Meckel's diverticulum during an 8-year period, 1993-2001, at Ewha Womans University Hospital was undertaken. Results : The male to female ratio was 2.3 : 1. The chief complaint was painless lower gastrointestinal( GI) bleeding; others were abdominal pain, abdominal distention and vomiting, in order of frequency. The diagonsis before surgery were Meckel's diverticulum in 5 patients, non-reducible intussusception in 3 patients and intestinal obstruction in 2 patients. The diverticulum was located between 35 cm to 70 cm proximal to the ileocecal valve. The length of the diverticulum ranged from 4 cm to 12 cm and 80% of it was within 5 cm. A Meckel scan($^{99m}Tc-pertechnetate$ scintigraphy) after cimetidine administration was done in 6 cases. All 5 cases that presented with lower GI bleeding had ectopic gastric mucosa confirmed on pathology. Out of 5 cases of ectopic gastric mucosa, only 4 cases were positive on the Meckel's scan. Conclusion : In cases of unexplained GI bleeding, obstruction, or inflammation diagnostic workup should be carried out to rule out Meckel's diverticulum. Laparoscopy, high resolution ultrasonography and computed tomography of the abdomen may be indicated in the assessment of pediatric patient with lower GI bleeding, especially in patients with suspected bleeding from Meckel's diverticulum showing negative Meckel's scan.

The pharmacological treatment of patent ductus arteriosus in premature infants with respiratory distress syndrome: oral ibuprofen vs. indomethacin (호흡곤란 증후군 미숙아에서 동맥관 개존증의 약물 치료 : 경구용 ibuprofen과 indomethacin의 비교)

  • Lee, Soo Jin;Kim, Ji Young;Park, Eun Ae;Sohn, Sejung
    • Clinical and Experimental Pediatrics
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    • v.51 no.9
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    • pp.956-963
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    • 2008
  • Purpose : Indomethacin is widely used for the prophylaxis and treatment of patent ductus arteriosus (PDA); however, it is associated with side effects such as renal failure, intraventricular hemorrhage, and gastrointestinal bleeding. Intravenous ibuprofen has been shown to be as effective as indomethacin in prompting PDA closure. If treatment with oral ibuprofen is as effective as indomethacin, it would have the advantages of greater availability, simpler administration, and lower cost. We conducted this study to compare the efficacy and side effects of indomethacin with those of oral ibuprofen, vis-$\grave{a}$-vis on the pharmacological closure of PDA. Methods : As a randomized double-blind study, 34 preterm infants with respiratory distress syndrome and hemodynamically significant PDA were treated with either intravenous indomethacin or oral ibuprofen. Echocardiography was performed by one cardiologist who was blind to the treatment that any given infant received. The rate of ductal closure, the need for additional drug treatment or surgical ligation, clinical outcome, and the side effects of drug treatment were compared. Results : Ductal closure occurred in 16 of 18 patients (88.9%) from the indomethacin group and in 14 of 16 patients (87.5%) from the ibuprofen group (P>0.05). Three patients in the indomethacin group and four in the ibuprofen group required a second drug treatment (P>0.05). Three patients (i.e., one patient in the indomethacin group and two in the ibuprofen group) underwent surgical ligation (P>0.05). Between the two groups, there was no significant difference vis-$\grave{a}$-vis in side effects or clinical outcome. Conclusion : Compared to indomethacin, oral ibuprofen has the advantages of simpler administration and lower cost, while being as effective; in addition, there are no differences between the two drug treatments with regards to side effects or clinical outcomes. Therefore, the widespread use of oral ibuprofen should be considered in treating PDA in preterm infants.

Seed Production by Induction of Male Flowers on Female Plants of Hemp(Cannabis saliva L.) (대마 자주의 웅화 유도에 의한 자성종자 생산에 관한 연구)

  • Moon, Youn-Ho;Koo, Bon-Cheol;Choi, Yoyng-Hwan;Ahn, Seung-Hyun;Bark, Surn-Teh;Cha, Young-Lok;An, Gi-Hong;Kim, Jung-Kon;Suh, Sae-Jung
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.55 no.4
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    • pp.327-332
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    • 2010
  • This study was conducted to overcome the deliciousness by sex reversal in hemp plants. When female plants grown under long day length condition were transferred to short day length condition in 3th and 6th leaf stage, a few male flowers were formed and the gap of flowering days between sex reversed male and normal female flowers were around 10 days and 3 days, respectively. Although the flowering amounts were small, this short gaps of flowering days were enough for artificial pollination. When female plants grown under long day length condition were transferred to short day length condition just after treatment of silver nitrate in the vegetative stage, a great amount of male flower was formed and the gap of flowering days between sex reversed male and normal female flowers were only 1 to 3 days. The increased sex reversed male flowers and induced short gap of flowering days were adequate for natural wind pollination. When female seeds were cultivated, seed yield was 141 kg/10a, while it was 96 kg/10a when normal seeds cultivated.