• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.335-340
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• 2000

A 3 valve-type pulse tube refrigerator optains its cooling effect from pressure drop by releasing the part of the charged gas through hot end nozzle. The objective of this study is to analyze the performance and to find an optimal expansion pressure of the 3 valve-type pulse tube refrigerator. It is assumed that gas lumps are not mixed and periodically repeat the adiabatic compression and expansion processes. And the nodal model is applied for the analysis of the regenerator. As the result of analysis, the optimum pressure at the end of expansion process was about 80-90% of the maximum pressure.

• Journal of Chest Surgery
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• 제25권1호
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• pp.66-72
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• 1992

From March 1986 to March 1991, 29 patients were operated due to cardiac tamponade at the Department of Thoracic and Cardiovascular Surgery, Masan Koryo General Hospital. Among them, 19cases were traumatic origin and 10 were Non traumatic origin. A] Traumatic cardiac tamponade Out of 19 cases, 12 cases were resulted from penetrating injury and 7 cases from trauma. Average time interval from arrival to operation was 91 minutes[15min.~8.5hr.] in penetrating injury group. On the other hand, average time of in cases of blunt trauma was more than 3hours because of the difficulties in diagnosis. Four deaths occured in 19 cases [mortality rate: 21.1%] 3 in blunt trauma group[42.9%] and 1 in penetrating group[8.3%]. In view of our experience, the prognosis was closely correlated with injury mode, initial vital sign and mental status. There was no close correlation between prognosis and cardiac injury site. B] Non traumatic cardiac tamponade The etiologies were malignancy[4], non-spesific pericarditis[3], tuberculosis[1], pyogenic[1] and cardiomyopathy[1]. All of the cases in which performed tube pericardiostomy were the cases that showed no response to conservative treatment and repeat per-icardiocentesis. There was one posoperative death.

• Corrosion Science and Technology
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• 제18권2호
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• pp.49-54
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• 2019

The purpose of this paper is to present failure analysis, of the heat exchanger tube in a district heating system. SS304 stainless steel is used, as material for the heat exchanger tube. The heat exchanger operates in a soft water environment containing a small amount of chloride ions, and regularly repeats operation and standstill period. This causes concentration of chloride ions on the outer surface of the tube, as well as repeat of thermal expansion, and shrinkage of the tube. As a result of microscopic examination, cracks showed transgranular as well as branched propagation, and many pits were present, at the initiation point of each crack. Energy disperstive spectroscopy analysis showed Fe and O peak, as well as Cl peak, meaning that cracks were affected by Cl ion. Failure of the tube was caused by chloride-induced stress corrosion cracking by thermal stress, high temperature, and localized enrichment of chloride ions.

• Design & Manufacturing
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• 제16권3호
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• pp.34-38
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• 2022

Regular expression pattern matching is widely used in applications such as computer virus vaccine, NIDS and DNA sequencing analysis. Hardware-based pattern matching is used when high-performance processing is required due to time constraints. ReCPU, SMPU, and REMP, which are processor-based regular expression matching processors, have been proposed to solve the problem of the hardware-based method that requires resynthesis whenever a pattern is updated. However, these processor-based regular expression matching processors inefficiently handle repetitive operations of regular expressions. In this paper, we propose a new instruction set to improve the inefficient repetitive operations of ReCPU and SMPU. We propose REMPi, a regular expression matching processor that enables efficient iterative operations based on the REMP instruction set. REMPi improves the inefficient method of processing a particularly short sub-pattern as a repeat operation OR, and enables processing with a single instruction. In addition, by using a down counter and a counter stack, nested iterative operations are also efficiently processed. REMPi was described with Verilog and synthesized on Intel Stratix IV FPGA.

• 대한족부족관절학회지
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• 제24권2호
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• pp.69-74
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• 2020

Osteochondral lesions of the talus (OLT) can heal and remain asymptomatic, or they can progress to deep ankle pain on weight bearing and the formation of subchondral cysts. Treatment varies from nonoperative treatment to open and arthroscopic procedures. Operative procedures include marrow stimulation techniques (abrasion chondroplasty, multiple drilling, microfracture), osteochondral autografts or allografts, and autologous chondrocyte implantation. Among these treatments, arthroscopic marrow stimulation techniques have been the preferred initial surgical treatment for most OLT. Despite these treatments, many patients complain of persistent pain even after surgery, and many surgeons face the challenge of determining a second line of treatments. This requires a thorough re-evaluation of the patient's symptoms as well as radiological measures. If the primary surgical treatment has failed, multiple operative treatments are available, and relatively more invasive methods can be administered. On the other hand, it is inappropriate to draw a firm conclusion in which methods are superior.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2080-2094
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• 2004

A model predictive controller is designed to control thermal power in a nuclear reactor. The basic concept of the model predictive control is to solve an optimization problem for finite future time steps at current time, to implement only the first optimal control input among the solved control inputs, and to repeat the procedure at each subsequent instant. A controller design model used for designing the model predictive controller is estimated every time step by applying a recursive parameter estimation algorithm. A 3-dimensional nuclear reactor analysis code, MASTER that was developed by Korea Atomic Energy Research Institute (KAERI), was used to verify the proposed controller for a nuclear reactor. It was known that the nuclear power controlled by the proposed controller well tracks the desired power level and the desired axial power distribution.

• 대한기계학회논문집B
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• 제33권5호
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• pp.358-364
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• 2009

This paper is to investigate the influence of driving patterns of slow and high speed vehicles on the performance of continuously regenerating diesel particulate filter(DPF) system matched with operating conditions in field application. The DPF performance test for field application was carried out for two identical DPFs installed to slow and high speed vehicles. A slow speed vehicle was selected among local buses which have driving patterns to repeat running and stop frequently, while a high speed vehicle was prepared to have long route of high speed over 60km/h like inter-city buses. In this test, the regeneration performance on the DPF of slow speed vehicle deteriorated because of high soot load index(SLI) in spite of same balance point temperature(BPT) distribution for high speed vehicle. The DPF of slow speed vehicle melted in the end because the rapid increase of back pressure caused high temperature over $1200^{\circ}C$ in the ceramic wall of DPF. The PM components like ash collected to the filter in the DPF were analyzed in order to investigate the cause of the defect and provide an operation performance of DPF system. In the result of the analysis, high levels of lubrication oil ash(Ca, Mg, P, Zn) were detected.

• 산업경영시스템학회지
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• 제41권4호
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• pp.171-178
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• 2018

Recently, the continuing operation of nuclear power plants has become a major controversial issue in Korea. Whether to continue to operate nuclear power plants is a matter to be determined considering many factors including social and political factors as well as economic factors. But in this paper we concentrate only on the economic factors to make an optimum decision on operating nuclear power plants. Decisions should be based on forecasts of plant accident risks and large and small accident data from power plants. We outline the structure of a decision model that incorporate accident risks. We formulate to decide whether to shutdown permanently, shutdown temporarily for maintenance, or to operate one period of time and then periodically repeat the analysis and decision process with additional information about new costs and risks. The forecasting model to predict nuclear power plant accidents is incorporated for an improved decision making. First, we build a one-period decision model and extend this theory to a multi-period model. In this paper we utilize influence diagrams as well as decision trees for modeling. And bayesian statistical approach is utilized. Many of the parameter values in this model may be set fairly subjective by decision makers. Once the parameter values have been determined, the model will be able to present the optimal decision according to that value.

• 지질공학
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• 제15권3호
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• pp.303-307
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• 2005

쌍천 유역 의 강수량과 지하수위의 관계를 분석 한 결과 갈수기 에 지 하수위가 현저히 저하됨을 확인하였다. 이 과정에서 70일 이동평균값을 이용한 지하댐 운영 지표(Groundwater dam Operation Index, COI)와 지하수위가 가장 높은 상관관계를 보여주었다. 유역 평균 일최대침투량을 알아내기 위하여 강수량자료를 일정값 이상은 고정하여 수정된 강수량자료로 70일 이동평균값을 구하고 이 값들과 지하수위와의 상관관계를 분석해 본 결과 40m가 일최대침투량으로 가정하였을 때 가장 높은 상관관계를 보여 주었다. 쌍천 유역의 경 우 40m가 한계 침투량이다. 쌍천 유역의 2003년부터 2005년까지 2개 년 자료에 대해서는 대체로 70일이 동평균을 이용한 COI와 지하수위와의 상관관계가 높으며 한계침투량을 고려했을 때 상관관계가 더 높아짐을 알 수 있다.

• Journal of Korean Neurosurgical Society
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• 제54권3호
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• pp.211-219
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• 2013

Objective : The objectives of the present study were to characterize the natural course of initially non-operated traumatic acute subdural hematoma (ASDH) and to identify the risk factors of hematoma progression. Methods : Retrospective analysis was performed using sequential computed tomography (CT) images maintained in a prospective observational database containing 177 ASDH cases treated from 2005 to 2011. Patients were allocated to four groups as followings; 136 (76.8%) patients to the spontaneous resolution group, 12 (6.8%) who underwent operation between 4 hours and 7 days to the rapid worsening group (RWG), 24 (13.6%) who experienced an increase of hematoma and that underwent operation between 7 and 28 days to the subacute worsening group (SWG), and 5 (2.8%) who developed delayed aggravation requiring surgery from one month after onset to the delayed worsening group (DWG). Groups were compared with respect to various factors. Results : No significant intergroup difference was found with respect to age, mechanism of injury, or initial Glasgow Coma Scale. The presence of combined cerebral contusion or subarachnoid hemorrhage was found to be a significant prognostic factor. Regarding CT findings, mixed density was common in the RWG and the SWG. Midline shifting, hematoma thickness, and numbers of CT slices containing hematoma were significant prognostic factors of the RWG and the SWG. Brain atrophy was more severe in the SWG and the DWG. Conclusion : A large proportion of initially non-operated ASDHs worsen in the acute or subacute phase. Patients with risk factors should be monitored carefully for progression by repeat CT imaging.