• 가족자원경영과 정책
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• 제7권1호
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• pp.135-152
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• 2003

This study examined which factors influence educational expenditure by family life cycle. Data for this study were from the 2001 Household Income and Expenditure Survey and consisted of a sample of 2,681 households. The results showed that the households having high school students had the highest educational expenditure and the households having middle school students had the highest ratio of educational expenditure to consumption expenditure. The education of household head, family type, the number of children, the age of the youngest child, and family income had significant effect on educational expenditure in all the stages of family life cycle. The results of this study will be useful for financial management of households and give suggestions for the government policy on education.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.645-649
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• 2005

In this study, redesign of a vaporizer sea-water pump has been carried out using computational fluid dynamics. The flow field of the specified pump model is simulated and analyzed. In the flow analysis full pump model has been used, and multi-block grids are employed to solve the governing equations. In order to improve pump efficiency, systematic redesign has been performed to remove the flow recirculation near the hub of the diffuser vanes. The modified model shows about 4 % improvement in pump efficiency compared to the given model.

• 한국유체기계학회 논문집
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• 제17권4호
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• pp.47-52
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• 2014

An inducer is forward-attached to an impeller to improve the suction performance. This paper described the experimental and numerical investigations on the concept of NPSH similarity about the inducer scale. As Reynolds number decreased for the same scale inducer, the hydraulic performance is slightly reduced because of the viscosity. The suction performance similarity is in good agreement. For different scale inducers, the NPSH similarity did not follow the conventional rule which is proportional to the square of the inducer diameter. A cavity of two times scale inducer grows faster under cavitation inception, and the head is more drop as the fluid passes blades. Because of the simplified cavitation model and vapor pressure, the NPSH similarity dose not have an accuracy. This study suggested an empirical formula for the NPSH similarity.

• 디지털산업정보학회논문지
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• 제7권4호
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• pp.31-37
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• 2011

Recently, MANET(Mobile Ad-hoc Network) is developing increasingly in the wireless network. MANET has weakness because phases change frequently and MANET doesn't have middle management system. Every node which consists of MANET has to perform data forwarding, but traceback is not reliable if these nodes do malicious action owing to attack. It also is not easy to find location of attacker when it is attacked as moving of nodes. In this paper, we propose a hierarchical-based traceback method that reduce waste of memory and can manage path information efficiently. In order to manage trace path information and reduce using resource in the cluster head after network is formed to cluster, method which recomposes the path efficiently is proposed. Proposed method in this paper can reduce path trace failure rate remarkably due to moving of nodes. It can also reduce the cost for traceback and time it takes to collect information.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.17-22
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• 2010

In this paper, numerical study on a mixed-flow pump for irrigation and drainage has been performed based on three-dimensional viscous flow analysis. Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by finite volume approximations and solved by the commercial CFD code ANSYS CFX-11.0. A structured grid system is constructed in the computational domain, which has O-type grids near the blade surfaces and H/J-type grids in other regions. The numerical results were validated with experimental data for the heads and efficiencies at different flow coefficients. The efficiency at the design flow coefficient is evaluated with the variation of two geometric variables related to area of discharge and length of the vane in the diffuser. The results show that efficiency of the mixed-flow pump at the design flow coefficient is improved by the modifications of the geometry.

• 한국화재소방학회논문지
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• 제32권1호
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• pp.24-32
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• 2018

수리계산방식에 의한 설계는 전산프로그램을 사용하는 방식과 직접 설계자가 계산에 의하여 설계하는 방식이 있다. 전산프로그램을 사용하는 경우 필요한 조건을 입력하면 프로그램에 의해 마찰손실, 유량, 양정 등을 계산하여 주지만 기본적인 개념과 절차를 모르게 되면 계산값이 입력자마다 다를 수가 있어 절차상의 기준을 정하는 것이 필요하다. 설계자가 직접 계산하는 경우에도 동일하다. 따라서 설계면적 내에서 수리계산의 절차를 다음과 같이 제시하였다. 가지관에 설치되는 티의 등가길이는 방출구(Outlet)의 관경이 다를지라도 설치된 배관의 관경과 동일한 관경(Run)의 등가길이를 선택한다. 가지관 중간에 손실값이 큰 다른 헤드가 있더라도 말단에서부터 계산해온 압력이 더 크다면 말단헤드에서부터 계산해온 압력으로 헤드방출량을 계산한다.

• 대한기계학회논문집B
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• 제35권10호
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• pp.1083-1088
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• 2011

임펠러 및 플로팅 링 실의 형상이 원심 펌프의 성능에 미치는 영향을 수류 시험 결과를 토대로 연구하였다. 연구 대상이 된 펌프는 30 톤급 및 75 톤급 액체로켓엔진용으로 개발된 단단 원심형 펌프로 연소실에 추진제(액체산소, 케로신)를 공급하는 터보펌프의 일부이다. 펌프의 양정은 임펠러 출구 폭 및 날개 개수, 날개의 출구 각도의 영향을 받는 것으로 나타났다. 또한 개발된 펌프는 플로팅 링 실의 간극에 따라 그 효율에 차이가 있었으며, 크기 증가에 따른 효율 증가 효과는 크게 나타나지 않았다.

• Archives of Plastic Surgery
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• 제37권3호
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• pp.239-244
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• 2010

Purpose: Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson's pseudoangiosarcoma, is a rare disease which is now considered as a reactive process of the endothelium rather than a benign neoplasm. It can occur in any blood vessels in the body but more common in the head and neck region as a solitary, often tender, bluish or reddish nodule. IPEH is characterized by the development of endothelial-lined papillary projections in a vascular lumen, usually associated with thrombotic material, the endothelial cells in the papillary structures showing only slight atypia and occasional mitotic Figures, the absence of tissue necrosis. Methods: 8 patients with IPEH were enrolled in the study from 2002 to 2007. All 8 lesions were surgically excised for histopathologic diagnosis. Results: 4 patients were female. The duration of the lesions ranged from 3 months to 15 years. The tumors were first noted between the ages of 20 and 72 years. 4 patients had lesions on the head; 2 on the toe; 1 on the back; and 1 on the finger, respectively. All lesions were solitary, ranged in size from 2 mm to 27 mm. There were no recurrences. Conclusion: The clinical appearance of IPEH is not specific, presented as a primary neoplasm, and the diagnosis can be established by microscopic examination. Complete surgical excision is the best choice of therapy for patients with IPEH, and is both diagnostic and curative. Awareness of this lesion will prevent incorrect diagnosis and overly aggressive treatment.

• 대한기계학회논문집B
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• 제41권7호
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• pp.445-453
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• 2017

본 연구에서는 RO용 고압 다단 펌프의 수력 부 성능에 대해서 연구를 수행하였다. 수력 부 설계는 크게 임펠러 설계와 레이디얼 디퓨저 설계로 나뉠 수 있다. 임펠러의 자오면 형상 변화에 따른 유동분포와 성능을 수치 해석적으로 연구하였으며, 임펠러 외경, 출구 폭, eye dia 등은 고정시킨 상태에서 반응 표면 기법을 이용하여 허브 및 쉬라우드 자오면 곡선을 변화 시키면서 성능을 최적화하였다. 해석결과 양정에 가장 큰 영향을 미치는 설계 변수는 ${\varepsilon}Ds$로 나타났으며 효율은 허브 입구 길이 및 쉬라우드 곡선이 가장 큰 영향을 주는 것을 알 수 있었다. 자오면 프로파일을 변경한 결과 기준모델(case 25)에 비해 약 0.5% 효율이 개선됨을 확인할 수 있었다.

• Journal of Preventive Medicine and Public Health
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• 제37권3호
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• pp.246-252
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• 2004

Objectives : Cancer is the leading cause of death in Korea. Therefore, a National Cancer Screening Program (NCSP) was launched in 1999. This study planned to evaluate the performance of the NCSP to identifying the influencing factors in relation to characteristic public health centers. Methods : To analyze the performance, the database of the NCSP records for 2002 was used. The performance index was measured by the goal achievement rate, which was defined by the real number of screenees against the expected number of screenees. Also, a survey was conducted by a self-administered questionnaire to identify the factors associated with the goal achievement rate. The questionnaire was divided into two sections. In the first section, the individual characteristics of the program coordinator in each public health center were measured, and second section was comprised of questions about the organizational characteristics associated with the NCSP. A total of 121 subjects from 241 public health centers completed the questionnaire. Results : Of the 121 public health centers (50.2% response rate), the average goal achievement rate was 72.8%. The results of the regression model showed that public health centers located in rural area (parameter estimates=38.2) and had great support from a head of center or province (parameter estimates=0.20) and tended to have higher goal achievement rates. However, the characteristics of the program coordinator, especially their knowledge of and attitude toward cancer screening, were not significantly related to the goal achievement rates. Conclusions : It appears that the most important associated factors to the goal achievement rate in the NSCP were the location of the public health center and the support for the NCSP from the head of the center or province.