• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.145-145
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• 2021

Water distribution networks (WDNs) are designed to satisfy water requirement of an urban community. One of the central issues in human history is providing sufficient quality and quantity of water through WDNs. A WDN consists of a great number of pipelines with different ages, lengths, materials, and sizes in varying degrees of deterioration. The available annual budget for rehabilitation of these infrastructures only covers part of the network; thus it is important to manage the limited budget in the most cost-effective manner. In this study, a novel pipe replacement scheduling approach is proposed in order to smooth the annual investment time series based on a life cycle cost assessment. The proposed approach is applied to a real WDN currently operating in South Korea. The proposed scheduling plan considers both the annual budget limitation and the optimum investment on pipes' useful life. A non-dominated sorting genetic algorithm is used to solve a multi-objective optimization problem. Three decision-making objectives, including the minimum imposed LCC of the network, the minimum standard deviation of annual cost, and the minimum average age of the network, are considered to find optimal pipe replacement planning over long-term time period. The results indicate that the proposed scheduling structure provides efficient and cost-effective rehabilitation management of water network with consistent annual budget.

• Korean Circulation Journal
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• 제52권6호
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• pp.414-428
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• 2022

Although tricuspid regurgitation (TR) is a general medical issue with growing prevalence and socioeconomic burden, most clinicians have not paid much attention to TR in the past. Several problems of TR have been pointed out in clinical practice, which include: ambiguous clinical manifestations and the difficulty in initial detection, limitations in generally used diagnostic tools, the absence of objective criterion for therapeutic intervention, high operative morbidity and mortality, and lack of long-term clinical data after the intervention for TR. Therefore, patients with TR usually visit clinicians at a much-advanced state, and this delay gives a major dilemma in clinical decision-making in a routine clinical practice. To improve the clinical outcome of TR, we need more knowledge about TR for solving the current problems and making strategies for better clinical practice. With this background, we have discussed in the present article about the pathophysiology of TR and the problems frequently experienced by clinical physicians in the diagnosis and treatment of TR. Furthermore, we have discussed the future strategy to improve the treatment of TR.

• 한국문헌정보학회지
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• 제4권
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• pp.43-71
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• 1975

Operations research has developed rapidly since its origins in World War II. Practitioners of O. R. have contributed to almost every aspect of government and business. More recently, a number of operations researchers have turned their attention to library and information systems, and the author believes that significant research has resulted. It is the purpose of this essay to introduce the library audience to some of these accomplishments, to present some of the author's hypotheses on the subject of library management to which he belives O. R. has great potential, and to suggest some future research directions. Some problem areas in librianship where O. R. may play a part have been discussed and are summarized below. (1) Library location. It is usually necessary to make balance between accessibility and cost In location problems. Many mathematical methods are available for identifying the optimal locations once the balance between these two criteria has been decided. The major difficulties lie in relating cost to size and in taking future change into account when discriminating possible solutions. (2) Planning new facilities. Standard approaches to using mathematical models for simple investment decisions are well established. If the problem is one of choosing the most economical way of achieving a certain objective, one may compare th althenatives by using one of the discounted cash flow techniques. In other situations it may be necessary to use of cost-benefit approach. (3) Allocating library resources. In order to allocate the resources to best advantage the librarian needs to know how the effectiveness of the services he offers depends on the way he puts his resources. The O. R. approach to the problems is to construct a model representing effectiveness as a mathematical function of levels of different inputs(e.g., numbers of people in different jobs, acquisitions of different types, physical resources). (4) Long term planning. Resource allocation problems are generally concerned with up to one and a half years ahead. The longer term certainly offers both greater freedom of action and greater uncertainty. Thus it is difficult to generalize about long term planning problems. In other fields, however, O. R. has made a significant contribution to long range planning and it is likely to have one to make in librarianship as well. (5) Public relations. It is generally accepted that actual and potential users are too ignorant both of the range of library services provided and of how to make use of them. How should services be brought to the attention of potential users? The answer seems to lie in obtaining empirical evidence by controlled experiments in which a group of libraries participated. (6) Acquisition policy. In comparing alternative policies for acquisition of materials one needs to know the implications of each service which depends on the stock. Second is the relative importance to be ascribed to each service for each class of user. By reducing the level of the first, formal models will allow the librarian to concentrate his attention upon the value judgements which will be necessary for the second. (7) Loan policy. The approach to choosing between loan policies is much the same as the previous approach. (8) Manpower planning. For large library systems one should consider constructing models which will permit the skills necessary in the future with predictions of the skills that will be available, so as to allow informed decisions. (9) Management information system for libraries. A great deal of data can be available in libraries as a by-product of all recording activities. It is particularly tempting when procedures are computerized to make summary statistics available as a management information system. The values of information to particular decisions that may have to be taken future is best assessed in terms of a model of the relevant problem. (10) Management gaming. One of the most common uses of a management game is as a means of developing staff's to take decisions. The value of such exercises depends upon the validity of the computerized model. If the model were sufficiently simple to take the form of a mathematical equation, decision-makers would probably able to learn adequately from a graph. More complex situations require simulation models. (11) Diagnostics tools. Libraries are sufficiently complex systems that it would be useful to have available simple means of telling whether performance could be regarded as satisfactory which, if it could not, would also provide pointers to what was wrong. (12) Data banks. It would appear to be worth considering establishing a bank for certain types of data. It certain items on questionnaires were to take a standard form, a greater pool of data would de available for various analysis. (13) Effectiveness measures. The meaning of a library performance measure is not readily interpreted. Each measure must itself be assessed in relation to the corresponding measures for earlier periods of time and a standard measure that may be a corresponding measure in another library, the 'norm', the 'best practice', or user expectations.

• 대한치과교정학회지
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• 제52권1호
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• pp.29-41
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• 2022

Objective: Condylar resorption (CR) is one of the major post-surgical complications of orthognathic surgery. This systematic review (SR) aimed to evaluate epidemiological data, risk factors, and therapeutical management of CR. Methods: Six databases were screened by two investigators until September 2020 to obtain all SRs. After reading the titles and abstracts, eligible SRs were determined and data extraction was performed. Using the latest version of A Measurement Tool to Assess Systematic Reviews, the methodological quality of the included SRs was determined. Results: Ten SRs with low or critically-low methodological quality were included in this review. Mandibular hypoplasia on the sagittal plane and hyperdivergent growth pattern on the vertical plane were the most common skeletal alterations in which CR could occur after orthognathic surgery. Post-operative condylar changes were analyzed both on two-dimensional and three-dimensional (3D) radiographic examinations. The incidence of CR was not related to the fixation method. Based on the severity of the pathological conditions, management of CR can include conservative or surgical therapy. Conclusions: Despite the limited evidence in literature, CR is considered a consequence of orthognathic surgery. However, an accurate diagnosis of CR and a better orthognathic surgical planning must include 3D radiographic examinations to improve pre- and post-surgical comparison. Well-designed studies with long-term follow-up and 3D data are needed to clarify the findings of this analysis..

• 한국농공학회논문집
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• 제65권5호
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• pp.25-35
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• 2023

The estuary reservoir is a major source of agricultural water in Korea; for effective and sustainable water resource management of the estuary reservoir, it is crucial to comprehensively consider various water resource factors, including water supply, flood, and pollutant management, and analyze future runoff changes in consideration of environmental changes such as climate change. The objective of this study is to estimate the impact of future climate change on the runoff characteristics of an estuary reservoir watershed. Climate data on future Shared Socioeconomic Pathway (SSP) scenarios were derived from two Global Climate Models (GCMs) of the Coupled Model Intercomparison Project phase 6 (CMIP6). The Hydrological Simulation Program-Fortran (HSPF) was used to simulate past and future long-term runoff of the Ganwol estuary reservoir watershed. The findings showed that as the impact of climate change intensified, the average annual runoff in the future period was higher in the order of SSP5, SSP3, SSP1, and SSP2, and the ratio of runoff in July decreased while the ratio of runoff in October increased. Moreover, in terms of river flow regime, the SSP2 scenario was found to be the most advantageous and the SSP3 scenario was the most disadvantageous. The findings of this study can be used as basic data for developing sustainable water resource management plans and can be applied to estuary reservoir models to predict future environmental changes in estuary reservoirs.

• 대한후두음성언어의학회지
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• 제31권1호
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• pp.19-26
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• 2020

Background and Objective Endoscopic airway dilation is the primary treatment for pediatric subglottic stenosis (SGS) due to its feasibility and non-invasiveness. The aim of this study is to evaluate the risk factors for the failure of endoscopic airway dilation in pediatric patients with SGS. Materials and Methods This study reviewed medical records of 38 pediatric patients had endoscopic dilation from a single and tertiary referral center, retrospectively. The success of the endoscopic dilation procedure was defined as no dyspneic symptom without tracheostomy or laryngotracheal reconstruction. Demographic profiles, underlying disease, and Myer-Cotton SGS severity grade were recorded. Success rates and risk factors for the failure of treatment were analyzed. Results The SGS patients with severity grade I was most common. After mean 1.8 numbers of procedures, there were 23 patients (60.5%) in the success group and 15 patients (39.5%) in the failure group. Age, sex, underlying diseases, and SGS severity grade were not significantly different between two groups. In patients who had multiple endoscopic procedures, the failure group showed SGS deteriorated after procedures in 66.7%, compared to 11.1% of the success group. In multivariable analysis, a long-term intubation (≥1 month) was identified as an independent risk factor for failure of endoscopic dilation procedure. Conclusion Although endoscopic dilation procedure is safe and effective for the management, repetitive endoscopic dilation may not give clinical benefit in patient with long-term intubation. Other airway procedures must be considered in those group of patients.

• Journal of Korean Neurosurgical Society
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• 제50권3호
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• pp.185-190
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• 2011

Objective : To investigate the efficacy of extracranial-intracranial (EC-IC) bypass surgery using a radial artery interposition graft (RAIG) for surgical management of cerebrovascular diseases. Methods : The study involved a retrospective analysis of 13 patients who underwent EC-IC bypass surgery using RAIG at a single neurosurgical institute between 2003 and 2009. The diseases comprised intracranial aneurysm (n=10), carotid artery occlusive disease (n=2), and delayed stenosis in the donor superficial temporal artery (STA) following previous STA-middle cerebral artery bypass surgery (n=1). Patients were followed clinically and radiographically. Results : Bypass surgery was successful in all patients. At a mean follow-up of 53.4 months, the short-term patency rate was 100%, and the long-term rate was 92.3%. Twelve patients had an excellent clinical outcome of Glasgow Outcome Scale (GOS) 5, and one case had GOS 3. Procedure-related complications were a temporary dysthesia on the graft harvest hand (n=1) and a hematoma at the graft harvest site (n=1), and these were treated successfully with no permanent sequelae. In one case, spasm occurred which was relieved with the introduction of mechanical dilators. Conclusion : EC-IC bypass using a RAIG appears to be an effective treatment for a variety of cerebrovascular diseases requiring proximal occlusion or trapping of the parent artery.

• 대한임상검사과학회지
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• 제36권2호
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• pp.121-126
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• 2004

The primary goal of six sigma is to improve patient satisfaction, and thereby profitability, by reducing and eliminating defects. Defects may be related to any aspect of customer satisfaction: high product quality, schedule adherence, cost minimization, process capability indices, defects per unit, and yield. Many six sigma metrics can be mathematically related to the others. Literally, six means six standard deviations from the mean or median value. As applied to quality metrics, the term indicates that failures are at least six standard deviations from the mean or norm. This would mean about 3.4 failures per million opportunities for failure. The objective of six sigma quality is to reduce process output variation so that on a long term basis, which is the customer's aggregate experience with our process over time, this will result in no more than 3.4 defect Parts Per Million(PPM) opportunities (or 3.4 Defects Per Million Opportunities. For a process with only one specification limit (upper or lower), this results in six process standard deviations between the mean of the process and the customer's specification limit (hence, 6 Sigma). The results of applicative six sigma experiment studied on 18 items TP, ALB, T.B, ALP, AST, ALT, CL, CK, LD, K, Na, CRE, BUN, T.C, GLU, AML, CA tests in clinical chemistry were follows. Assessment of process performance fits within six sigma tolerance limits were TP, ALB, T.B, ALP, AST, ALT, CL, CK, LD, K, Na, CRE, BUN, T.C, GLU, AML, CA with 72.2%, items that fit within five sigma limits were total bilirubin, chloride and sodium were 3 sigma. We were sure that the goal of six sigma would reduce test variation in the process.

• 정보처리학회논문지D
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• 제19D권1호
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• pp.95-104
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• 2012

본 연구의 목적은 금융IT 발전의 거시적 관점에서 방향성을 제안하고, 국내 금융IT 환경의 변화과정에 대한 경험적 모델을 바탕으로 향후 진행될 금융IT 시스템의 이론적 근거를 제시하는데 있다. 이를 위해 금융IT 발전과정 40년 동안 중요한 영향을 미쳤던 의미있는 패턴들을 도출 및 분석하고 코어뱅킹 모델의 라이프사이클을 역 추적하였다. 연구결과 첫째, 우리나라 금융IT 시스템의 라이프사이클은 10년으로 분석되었다. 둘째, 코어뱅킹 모델의 라이프사이클은 평균11년으로 분석되었으며 최장기 모델의 라이프사이클은 33년으로 분석되었다. 셋째, 장기 생존 코어뱅킹 모델들은 초기부터 철저한 객관적 분석과 벤치마킹을 통해 설계되고 발전시켜 왔다. 넷째, 금융IT 분야는 융합산업 분야로 성장시켜 나가야 하며, 이를 위해 코어뱅킹 모델연구의 체계화와 전문인력 양성이 필요하다. 본 연구는 그동안 명확하게 정리되지 않았던 코어뱅킹 모델의 분석을 통해 새로운 방향성을 제시하였다는데 의의가 있다. 전반부에는 코어뱅킹 모델의 역추적 의미와 금융IT 경영전략 차원의 핵심요소들을 중심으로 조사하였고, 후반부에는 이를 근거로 본격적인 코어뱅킹 모델의 라이프사이클을 분석하였다.

• 디지털융복합연구
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• 제14권9호
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• pp.341-348
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• 2016

본 연구의 목적은 노인들의 저작 능력과 구강건강영향지수(OHIP-14)를 이용하여 구강건강 관련 삶의 질과의 관련성에 대하여 조사하고자 하였다. 총 195명의 노인들을 대상으로 주관적인 저작능력과 객관적인 저작능력 그리고 삶의 질에 관한 OHIP-14를 조사하였다. 저작능력이 낮을 경우 삶의 질이 나쁠 위험비가 증가하였고, 나이, 거주형태, 교육수준, 틀니의 사용을 보정한 결과 주관적 저작 능력은 삶의 질이 낮아질 위험비가 2.42배(p<0.05) 높게 나타났으며, 객관적인 저작 능력은 7.58배(p<0.001) 높은 것으로 나타났다. 본 연구에서는 저작 능력이 노인들의 삶의 질을 나타내는 OHIP-14 총 점수와 관련이 있는 것으로 나타났다. 노인들이 저작능력이 구강건강 관련 삶의 질에 영향을 미친다는 것을 확인하였다. 이에 다양한 후속 연구들이 장기적으로 진행되어 건전한 구강건강 유지와 함께 노인들의 삶의 질을 향상시키는데 도움이 되기를 바란다.