• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1328-1334
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• 2010

As the life quality is higher and higher, the requirement for the clean air in a subway station is strongly being increased. Therefore, many researches have been performed about that. Seoulmetro has taken many parts and has applied latest products for the higher level of air quality. However, by various kinds of facilities, it is hard to maintain the facilities and verify their performances. Therefore it is better to use qualified air filter system by the performance test at subway stations than to apply newly developed one without any verification. This study is focused on the performance verification for a panel structure, which consists of non-woven fabric, to suggest the standard of air filter systems.

• 대한가정학회지
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• 제20권4호
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• pp.125-132
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• 1982

The purpose of this study was to see that how about the variables of homemaker's age, marital periods, children numbers, homemaker's employment, family types, house types, family income, homemaker's education level, and the convenience of kitchen and laundry influence on homemaker's household preferences. On this study, the household tasks were classified into the tasks on Care of clothes, Mal preparation and clean-up, Care of the house, Care of the family members, and Marketing and record keeping. Questionaires were given to randomly selected homemakers in Busan in July, 1982. Data from the 736 respones were analyzed according to Multi regression and T-test. The results were as follows: 1. The variables affecting the homemaker's household preferences were marital periods, family income and the convenience of kitchen and laundry. Longer the marital periods, higher the family income and more feeling the convence were taken higher preferences on household tasks. 2. The variable of age was less significantly related to the homemaker's household preferences than the marital periods. 3. The variable of house types was less significantly related to the homemaker's household preferences than the convenience of kitchen and laundry.

• 마이크로전자및패키징학회지
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• 제22권1호
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• pp.69-74
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• 2015

첨단 전자기기에 사용되는 전자부품의 크기와 접속피치가 감소하면서 리플로우 공정 후 플럭스 잔사의 세정이 어려워짐에 따라 무세정 솔더 페이스트에 대한 요구가 증가하고 있다. 본 연구에서는 SAC305 솔더분말과 에폭시 레진을 주성분으로 하는 경화성 플럭스를 혼합하여 제조한 에폭시 경화형 솔더 페이스트에 대하여 리플로우 공정성, 플럭스 잔사의 부식성, 솔더볼 및 보드레벨 BGA 패키지 솔더 접합부의 기계적 거동을 기존 로진계 솔더 페이스트와 비교하여 평가하였다. 에폭시 경화형 솔더 페이스트는 솔더 접합부 주변에 경화물 필렛을 형성한 것으로 보아 플럭싱 작용에 의해 솔더 접합부가 형성된 이후에 경화반응이 진행되는 것을 확인할 수 있었으며, 동판에 대한 젖음성 시험을 통해 기존상용 솔더 페이스트 정도의 납퍼짐성을 갖는 것을 알 수 있었다. 리플로우 후 동판에 대한 고온 고습 시험을 통해 에폭시 경화형 솔더 페이스트는 동판 부식을 전혀 발생시키지 않는 것으로 나타났는데, 이는 FT-IR 분석결과 에폭시 경화반응을 통해 단단히 고정된 결과로 생각되었다. 볼전단, 볼당김 및 다이전단 시험 결과, 솔더 접합부 주변에 형성된 경화물 필렛은 솔더 표면과 접착본딩을 형성하며, 다이전단강도를 15~40% 정도 향상시키는 것으로 보아 에폭시 경화형 솔더 페이스트는 플럭스 잔사 세정공정의 생략과 함께 솔더 접합부 보강효과를 통해 패키지 신뢰성 향상에도 기여할 수 있을 것으로 생각되었다.

• 농촌계획
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• 제5권1호
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• pp.35-44
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• 1999

The purpose of this study is to find the bi-polar adjectives for rural stream landscape evaluation by the semantic differential scale and to suggest the major determinants of visual preference in rural stream landscapes. For this, the bi-polar adjectives for rural stream landscape evaluation was found by the method of the reliability test, and the spatial image was analyzed by the factor analysis. The level of visual preference was measured by slide simulation test, and these data were analyzed by the multiple regression. The major findings of this study can be summarized as follows : 1) Of the bi-polar adjectives expressing psychological and physical characteristics, the hi-polar adjectives which demonstrated reliability and consistency run as follows : Bi-polar adjectives expressing psychological characteristics : 'calm-bustling', 'unfamiliar-familiar', 'still-active','depressing-brisk', 'discomfortable-comfortable', 'suppressed-free', 'lifeless-living', 'quiet-noisy', 'unpleasant-pleasant'. Bi-polar adjectives expressing physical characteristics : 'artificial-natural', 'narrow-wide', 'rocky-not rocky', 'desolate-fertile', 'dirty-clean', 'enclosed-open', 'flat-steep', 'not gravelly-gravelly', 'thicketed-not thicketed', 'not weedy-weedy'. 2) Two factors, the harmony and the movement, were derived from the factor analysis for the psychological variables. Three factors, the naturalness, the rock, and the vegetation, were derived from the factor analysis for the physical variables. 3) Rural stream landscape types were classified into four types by the multi-dimensional scaling method. Type III, IV obtained higher rank of visual preference and type I, II obtained lower. 4) For all types, the factors determining the level of visual preference were found to be the harmony, the naturalness, and the vegetation. The visual preference determinants of rural stream landscape need to be considered in improving or restoring the rural stream landscapes.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.4732-4737
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• 2011

진공집진 스탠딩 그라인더는 그라인딩을 하면서 동시에 발생하는 분진을 집진하는 것으로서, 산업현장에서 도장하기 전에 도장 표면이나 용접 후 비드 부위를 깨끗하게 하기 위하여 필요하다. 최근에 스탠딩 그라인더는 연마 및 분진집진 용량이 커졌으나 반면에 발생소음이 적고 컴팩트하고 포터블화하는 추세이다. 이러한 연마와 집진 성능이 증가함에 따라서 소음과 중량이 중요한 문제로 야기된다. 이러한 문제를 해결하기 위하여 효율적인 사이클론을 Ansys-CFX에 의하여 해석하여 설계하고 실험을 거쳐서 개발되었으며, 그 결과, 그라인더부의 중량은 5.9kg로서 작업자가 충분히 들고 작업을 할 수 있으며, 개발 제품의 소음은 69.9dB(A)로서 좋은 결과를 얻었다.

• 대한간호학회지
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• 제11권1호
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• pp.19-27
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• 1981

This Study was conducted at Intensive Care Unit of H & S Hospitals from Jan 4 to April 7, 1981 on 14mail & 26female adult patients. Each patient was screened and found to have nonbacteriuria in clean catch specimen before catheterization. Clean catch apecimen through Foley catheter were obtained after 24hours, 48hours and 72hours from catheterization. The result of this study is reviewed in a statistical analysis of percentage ＆ Chi Square test to obtain the following findings. 1) The occurenc of bacteriuria in patients according to duration of indwelling catheter. a. 9.1％ of the patient showed evidence of bacteriuria 24hours post catheterization specimen and 60％ showed 48hours post cathetreization, while 68.4％ of the patient showed evidence of bacteriuria 72hours post catheterization specimen. The occurence of bacteriuria in patients were significant differences at 1％ level between duration of indwelling catheter. b. Mail patients had no infection 24hours post catheterization, 50％ displayed bacteriuria 48hours post catheterization ＆ 62.5％ displayed bacteriuria 71hours post catheterization. 11.1％ of femail patients displayed infection 24hours post catheterization 66.7％ displayed infection 48hours post catheterization and 72.7％ displayed infection 72hours post catheterization. There were significant differences at 1％ level between bacteriuria occurence of mail ＆ femail patients and the duration of insertion. 2) 56％ of those patient who have altered mental state developed bacteriuria, while 40％ of those patient who have alear mental state developed bacteriuria. But there was without statistically any significant difference between patient's mental status. 3) The occurence of bacteriuria with the administration of antibiotics in 36 patient was in 50％. The occurence of bacteriuria without the administration of antibiotics in 4 patients was in 50％. But there was without statistically any significant difference between the administration of antibiotics. 4) The occurence of bacteriuria in patients according to frequency of bladder irrigation. 50％ of those patient who irrigated twice a day developed bacteriuria, 63.6％ of those patient who irrigated once a day developed bacteriuria. The occurence of bacteriuria in patients were significant differences at 1％ level between frequency of bladder irrigation. 5) The occurence of bacteriuria in patients who did perineal care once a day was 58.1％, 22.6％ of those patient who did perineal care twice a day developed bacteriuria. But there was without statistically any signiticant differences between frequency of perineal care. 6) Most frequent bacteria of all bacterial strains isolated by culture of the urine was E. coli(45％). Enterococci & Staphylococcus were 15％ respectively.

• 자원환경지질
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• 제54권4호
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• pp.483-494
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• 2021

본 연구에서는 폐금속광산과는 달리 우려기준 전후의 낮은 비소 오염농도 분포특성을 가지는 폐석탄광산 농경지 토양을 대상으로 광해방지사업(토양개량·복원사업) 시 복토층의 두께 감소 가능여부를 벼를 식재한 담수형 컬럼실험을 통해 검토하였다. 담수 후 4개월 동안 토양용액의 pH, EC, ORP 및 무기원소(Fe, Mn, Ca, As) 농도를 모니터링한 결과 컬럼하층에서 상층으로 미치는 영향은 높지 않은 것으로 나타났다. 복토 두께에 따른 비교에서도 하층의 영향보다는 복토층 두께 변화에 따른 ORP 변화가 복토재 무기원소의 거동에 영향을 미치는 결과를 보였다. 이러한 결과는 토양용액의 거동이 상하층간 반응의 영향보다는 각 층별 나타나는 토양의 이질성에 우선하여 나타난 것으로 판단되었다. 모니터링 종료시점에서 채취한 벼 뿌리의 비소 농도는 현행 사업 조건과 같은 40 cm 두께의 복토층을 조성한 경우 컬럼하층의 안정화 처리여부에 상관없이 대조구 대비 98%가 감소되었다. 20 cm 두께의 복토층에서는 오염토의 안정화가 없을 경우 58%, 안정화처리 시 80%의 전이감소 효율을 나타내었다. 따라서 오염 농경지 토양에 대한 적정 안정화 처리를 수행할 경우 복토재의 사용량을 감소시킬 수 있으며, 경제적인 사업수행효과도 이룰 수 있을 것으로 판단된다.

• 한국대기환경학회지
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• 제27권2호
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• pp.181-190
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• 2011

The air pollutants from vehicle exhaust gas are affected by many factors including fuel qualities, engine and vehicle technologies, driving patterns. In particular, fuel qualities and after-treatment devices could directly affect the emission level of pollutants. The pollutant reduction characteristics that caused by enforced fuel quality standard were analyzed. Three types of test fuel were selected in accordance with Korean automotive fuel standard in 2006, 2009, 2012 and used for vehicle emission test in chassis dynamometer. European COPERT correction equation of fuel impact was considered as reference information to quantify the vehicle emission test results. The contribution rates of exhaust emission by COPERT correction equation showed that aromatic compounds and oxygen contents in gasoline fuel was most important. In case of diesel fuel, cetane index and polycyclic aromatic compounds accounted for the greater part. The exhaust emission effects by COPERT correction equation revealed that CO and VOC was increased 0.86%, 1.57% respectively in after 2009 gasoline when compared to before 2009 gasoline fuel. In case of light-duty diesel vehicle CO, VOC and PM were decreased in range of 3~7%. The result from this study could be provided for developing future fuel standards and be used to fundamental information for Korean clean air act.

• 한국추진공학회지
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• 제17권1호
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• pp.1-8
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• 2013

단일액체추진제 하이드라진 추력기는 간단한 구조, 우수한 추진제 저장성, 깨끗한 반응생성물 기체 등과 같은 장점으로 수많은 우주비행체의 궤도 및 자세제어시스템으로 적용되고 있다. 우주발사체의 자세제어시스템에 적용하기 위한 중형급 하이드라진 추력기가 설계 제작되었으며, 성능검증을 위해 수행된 개발모델 추력기의 지상연소시험 결과를 추력, 임펄스 비트, 그리고 엔진 구성품별 온도 및 압력 등을 통하여 제시한다. 개발모델 엔진은 매우 우수한 추력 응답성과 재현성을 보였고, 그 추력성능 효율은 이론설계치 대비 93% 이상임을 확인할 수 있었다.

• Tribology and Lubricants
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• 제39권1호
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• pp.1-7
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• 2023

Fluid pumps in chemical processes are typically driven by electric motors. Even if the motor is separated from the pump with seals, wear resulting from friction and misalignment can lead to leakage of chemical fluid, causing corrosion in the bearing supporting the motor, and, eventually, failure of the motor. It is thus a standard procedure to replace bearings at regular intervals. In this article, we propose 3D-printed plastic ball bearings for use as an alternative to commercial stainless-steel ball bearings. The plastic bearings are easy to manufacture, require less time to replace, and are chemically resistant. To validate the applicability of the plastic bearings, we first conducted chemical resistance tests. Bearings were immersed in 30 caustic acid and 30 nitric acid for 30 min and 24 h, respectively. The test results showed no corrosive damage to the bearings. A test rig was set up to compare the performance of the plastic bearings with that of the commercially equivalent deep-groove ball bearings. Loading test results showed that the plastic bearings performed as well as the commercial bearing in terms of vibration level and load-handling capability. Finally, a plastic bearing was subjected to a clean-in-place process for three months. It actually outperformed the commercial bearing in terms of chemical resistance. Thus, 3D-printed plastic bearings are a viable alternative to stainless-steel ball bearings.