• 한국해양공학회지
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• 제25권5호
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• pp.21-26
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• 2011

Seawater lift pump systems are responsible for maintaining open canal levels to provide the suction flow of circulating water pumps at the set point. The objective of this paper is to design a 2-stage mixed flow pump (for seawater lifting), investigate the new impeller modeling method, and performance improvements of the impeller by using a commercial CFD code. The rotating speed of the impeller is 1,750 rpm with a flow rate of 2,700 m3/h. A finite volume method with a structured mesh and realized k-${\varepsilon}$ turbulent model is used to guarantee a more accurate prediction of turbulent flow in the pump impeller. The performance variables such as the static head, brake horsepower, and efficiency of the mixed flow pump are compared based on changes in the impeller blade shape.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.403-410
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• 1995

A loss of the residual heat removal (RHR) accident during mid-loop operation of Yong-gwang Nuclear Units 3/4 was analyzed using the RELAP5/MOD3.1.2 code. In this work the following assumptions are used; (i) initially the reactor coolant system (RCS) above the hot leg center line is filled with nitrogen gas, (ii) two 3/4-inch diameter vent valves on the reactor vessel head and the top of pressurizer in the reactor coolant system are always open, and a level indicator is connected to the RMR suction line, (iii) the two steam generators are in wet layup status and the steam generator atmospheric dump valve assemblies are removed so that the secondary side pressure remains at nearly atmospheric condition throughout the accident, and (iv) the loss of RHR is presumed to occur at 48 hours after reactor shutdown. Findings from the RELAP5 calculations are (i) the core boiling begins at ∼5 min, (ii) the peak RCS pressure is ∼3.0 bar, which implies a possibility of temporary seal break, (iii) ∼94 % of the decay heat is removed by reflux condensation in the steam generator U-tubes in spite of the presence of noncondensable gas, (iv) the core uncovery time is evaluated to be 7.2 hours. Significant mass errors were observed in the calculations.

• 한국산학기술학회논문지
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• 제20권9호
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• pp.150-155
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• 2019

공동현상은 유체의 속도 변화에 의한 압력변화로 인해 유체 내에 빈 곳이 생기는 현상을 말한다. 고속의 액체유동에서 액체의 압력이 포화증기압 이하로 낮아져서 액체 내에 증기 기포가 발생하는 현상이다. 본 연구에서는 선박 및 해양플랜트 분야에서 사용되어지는 유체기기에 대해 CFD 유동해석을 이용하여 선박용 프로펠러의 단독성능 해석기법의 타당성 확보 및 공동에 따른 유동양상을 파악하기 위해 FLUENT를 이용하여 전진비를 증가시키며 3차원 해석을 수행하고 MOERI의 실험 데이터와 비교분석하였다. 대형 컨테이너선용 KP505프로펠러의 사양을 기준으로 전진비에 따른 해석의 결과 전진비 0.7~0.8 구간에서 효율은 60% 수준으로 가장 높게 확인되었다. 압력면과 흡입면의 차이로 추력이 발생되는 것을 확인하였고 프로펠러 표면보다는 이면부근에서 Bubble이 많이 생성될 것으로 추정되며 공동현상이 더 많이 발생할 것이라 추정되었다. 또한 전진비가 증가함에 따라 공동현상은 급격히 감소함을 알 수 있었다. 추력계수와 토크계수는 MOERI 실험값과 비교했을 때 비교적 유사한 결과를 나타내었으며 전진비 1을 제외하고 모두 5%이내의 차이를 나타내었다. 따라서, CFD로 프로펠러 단독 성능에 대한 평가가 가능함을 확인하였다.

• 임상간호연구
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• 제19권1호
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• pp.1-19
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• 2013

Purpose: This study was conducted to develop standards to ensure nursing process-based care of oxygen therapy and airway suctioning and to develop a performance measurement tool to evaluate the care applied according to the standards, and finally to determine validity of the standards and the tool. Methods: The standards and the tool were reviewed by a panel of experts and refined based on the panel's suggestions. Validity of the standards and the tool were examined through surveying a total of 366 hospital nurses. Results: The mean validity scores of the performance measurement standards and the tool were 3.58 and 3.55, respectively, out of 4.00. So the performance measurement standards and the tool in this study were found to be acceptable in evaluating quality of nursing care provided at patient admission and discharge. Conclusion: This result indicates that the performance measurement standards and the tool developed in this study are valid instruments to monitor and improve quality of nursing care for oxygen therapy and airway suctioning.

• 유기물자원화
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• 제17권1호
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• pp.96-102
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• 2009

본 연구에서는 혐기성 소화 성능 향상을 위해 초음파 및 알칼리 전처리에 의한 폐활성 슬러지의 가용화 효과를 조사하였다. 초음파 및 알칼리 전처리는 세포벽의 파괴로 인하여 모세관 흡입 시간을 증가시킬 뿐만 아니라 상등액의 용존성 화학적 산소요구량, 단백질 및 탁도 농도를 증가키는 것으로 나타났다. 알칼리와 초음파 전처리를 병행한 슬러지 가용화가 초음파 전처리만을 수행한 경우에 비해 용존성 화학적 산소요구량과 단백질 증가가 높은 것으로 나타났다. 알칼리와 초음파 전처리를 동시에 수행한 경우 폐활성 슬러지의 고형물 농도 증가에 따라 가용화 효율이 감소하는 것으로 조사되었다.

• 대한관절경학회지
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• 제4권1호
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• pp.38-41
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• 2000

목적 : 보존적 치료에 반응하지 않는 슬개골전 점액낭염에 대하여 점액낭 내벽의 염색후 관절경을 이용한 절제술을 시행하여 고무적인 결과를 얻었기에 그 임상적 결과를 보고하고자 한다. 대상 및 방법 : 1996년 1월부터 1998년 10월까지 본 교실에서 치료받은 20세 이상의 슬개골전 점액낭염의 환자중 관절경적 절제술을 시행받은 환자 11명을 대상으로 하였다. 수술방법은 앙와위에서 점액낭내로 관절경을 삽입후 메틸렌 블루를 이용하여 내벽의 염색을 시도한후 shaver를 이용하여 내벽을 제거후 지속적 폐쇄 흡입기를 설치한후 압박 드레싱한후 보행을 허용하였다. 결과 : 모든 환자에서 동통을 수반한 반흔은 없었으며 수술 직후부터 보행이 가능하였으며, 추시 관찰중 1례에서 지연 감염이 있었다. 결론 : 관절경을 이용한 슬개골전 점액낭염의 치료는 합병증을 최소화 할 수 있으며, 특히 시술시 점액낭 내벽을 염색함으로써 병변 조직의 구별이 용이하여 슬개골전 점액낭염의 치료에 있어 좋은 술식으로 생각된다.

• 대한기계학회논문집B
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• 제39권8호
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• pp.645-651
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• 2015

본 논문은 중앙구동 이젝터의 유량비에 미치는 설계변수의 영향에 대한 연구를 목적으로 한다. 중앙구동 이젝터의 설계변수는 구동노즐 출구 단면적 및 거리비, 디퓨저 출구 단면적비로 설정하였다. 실험장치는 가변노즐 이젝터, 전동 모터-펌프, 구동유체 저장수조, 제어판넬 그리고 고속 카메라 시스템으로 구성하였다. 유량비는 실험변수에 따라 측정되는 유입 공기량과 구동유체인 물의 유량을 이용하여 도출하였다. 유량비는 구동노즐 거리비와 혼합관 길이비가 커지면 증가하는 반면에, 구동노즐 면적비와 디퓨저 출구 면적비가 커지면 감소하였다.

• Archives of Plastic Surgery
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• 제35권4호
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• pp.393-399
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• 2008

Purpose: Chronic infected wounds sustained over 4 weeks with exposed tendon or bone are difficult challenges to plastic surgeons. Vacuum assisted closure (VAC) device has been well used for the management of chronic wounds diminishing wound edema, reducing bacterial colonization, promoting formation of granulation tissue and local blood flow by negative pressure to wounds. But Commercial ready-made VAC device might have some difficulties to use because of its high expenses and heavy weight. So we modified traditional VAC device with silver dressing materials as topical therapeutic agents for control of superimposed bacterial wound infection such as MRSA, MRSE and peudomonas. Methods: We designed the modified VAC device using wall suction, 400 cc Hemovac and combined slow release silver dressing materials. We compared 5 consecutive patients' data treated by commercial ready-made VAC device(Group A) with 11 consecutive patients' data treated by modified VAC device combined with silver dressing materials(group B) from September 2004 to June 2007. Granulation tissue growth, wound discharge, wound culture and wound dressing expenses were compared between the two groups. Results: In comparison of results, no statistical differences were identified in reducing rate of wound size between group A and B. Wound discharge was significantly decreased in both groups. Modified VAC device with silver dressing materials showed advantages of convenience, cost effectiveness and bacterial reversion. Conclusion: In combination of modified VAC device and silver dressing materials, our results demonstrated the usefulness of managing chronic open wounds superimposed bacterial infection, cost effectiveness compared with traditional VAC device and improvement of patient mobility.

• Tribology and Lubricants
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• 제37권6호
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• pp.246-252
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• 2021

Among the engine components of an internal combustion engine, the valve train is a series of systems that supply intake gas to the combustion chamber and operate intake and exhaust valves that discharge exhaust gas. If excessive wear occurs in the valve train system, the suction and exhaust valves do not open and close on time, which leads to abnormal combustion and exhaust gas. In this study, we conduct experiments and analyses on friction and wear characteristics of the valve train system. Moreover, we experimentally study the correlation between the pinball and pinball cap on engine oil lubrication, friction experiment, wear amount analysis, and surface analysis. Specifically, we experiment using Ball on reciprocating tribo-tester and apply commercial engine oil sold on the market engine oil. We construct the experimental conditions for each new oil and oil. Accordingly, the completed specimen was subjected to a confocal microscope to check the wear volume, observe the surface of the specimen, and confirm the elemental components using a scanning microscope (SEM) and an energy dispersion X-ray spectrometer (EDS). Through this experiment, we analyze the friction and wear characteristics of valve train components according to engine oil grade, and the obtained data serve as an effective engine oil management method.

• Journal of Chest Surgery
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• 제8권1호
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• pp.37-44
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• 1975

Authors have reviewed the records of seven patients of multiple rib fractures with severe flail chest who were admitted to Hanyang University Hospital during the 3 years period from 1972 through 1975. Of the seven patients studied, automobile accidents led to the injuries in 4 cases, two patients were injured in fall from a tree and on the ox-heading. All who had a blunt trauma without any open wound on the chest. The numbers of the fractured ribs accounted for 6 to 9 of the ribs including double fractures from 3 to 5 ribs. The left side fractures occurred in the 6 patients and in the right only one patient. Thus the flail segment was more often located in the left antero-lateral position than in the right lateral position [the ratio was 6:1].. All cases had associated injuries. The injuries and multiple fractures were the most common associated injuries occurring in four and five of the patients respectively. The patients were classified as having associated head injuries when they were admitted in comatose or semicomatose state. When a major degree of instability of the thoracic cage exists, adequate respiratory change is not possible. For this reason the tracheostomy was performed in five patients in an acutely injured patient with flail chest only after an endotracheal tube has been inserted or after an endotracheal suction. All patients had secondary complications in the pleural cavity, such as hemothorax or hemopneumothorax with or without intrapulmonary hemorrhage and subcutaneous emphysema. Therefore, closed thoracostomy was performed in five patients in the emergency room. The thoracotomy was required in four patients: immediate operation without closed thoracostomy was performed in two patients and the thoracotomy was indicated in two patients after closed thoracostomy, because of increasing intrathoracic hemorrhage. As to the fixation of the flail segments, authors employed two techniques; one was towel clip traction of the flail segments and the other was intramedullary insertion of Kirschner`s wire in to the double fractured rib fragments for the fixation of the flail segments [Kirschner`s wire fixation]. Because` of an different results in the course of treatment between two techniques, data from patients with towel clip traction was compared with those from patients with thoracotomy and Kirschner`s wire fixation of the flail segments. Of the three patients with towel clip traction, two patients required bronchoscopic toilet due to lung atelectasis which developed because of inadequate motion of thoracic cage and poor expectoration. This was in contrast to the four patients with thoracotomy and Kirschner`s wire fixation, who didn`t these complication because of adequate motion of the thoracic cage and subsequent good expectoration.