• Journal of Preventive Medicine and Public Health
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• 제21권1호
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• pp.47-60
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• 1988

The monthly ambulatory treatment days in newly detected hypertension group and known hypertension group were analyzed. The population was identified through the records of screening examination given by Korea Medical Insurance Corporation during the period from April to July, 1986. From the records of screening examination, 11,614 hypertensive patients were identified. By random sampling,959 patients were selected : among them, 544 fell under the category of known hypertension group and the other 415 fell under the newly detected hypertension group. The monthly ambulatory treatment days of these patients during the period from the April, 1985 to September, 1987 were analyzed in order to compare the exents of medical care utilization as well as to define and analyze the determinants responsible for the ambulatory treatment days between the two groups. The following results were obtained. 1) In the known hypertension group, no statistically significant changes in the ambulatory treatment days was observed after, in comparision to before, the screening examination. However, in the newly detected hypertension group the medical care utilization increased after the screening examination because of hypertension. 2) The ambulatory treatment days for hypertension of the known hypertension was statistically significant and higher than that of the newly detected hypertension group after screening examination. 3) There was no statistically significant change in the ambulatory treatment days in association with diseases other than hypertension in either group before and after the screening examination. 4) There was no statistically significant variable responsible for ambulatory treatment days in the known hypertension group. However, the income was a statistically significant variable in the newly detected hypertension group. 5) After the screening examination, the variables determining the ambulatory treatment days were the age of the patient and the diastolic blood pressure in the known hypertension group. These variables responsible for 2.02% of the total ambulatory treatment days. In the newly detected hypertension group, the income was a statistically significant variable which was responsible for 2.10% of total ambulatory treatment days. The above results satisfied the hypothesis that there would be no significant changes in the ambulatory treatment days before and after the screening examination in the known hypertension group. Also the hypothesis that there would be no significant change in the exents of medical care utilization for the diseases other than hypertension before and after the screening examination in either group was satisfied Also the medical care utilization was significantly higher in the known hypertension group than the newly detected hypertension group after the screening examination. This finding satisfied the hypothesis. This study was limited by the lack of considering fully the variables reponsible for the clinical symptoms of hypertension as well as for the individual characteristics. Thus, the result of this study are not fully adequate to define the determinants responsible for the exents of medical care utilization. In the future studies on medical rare utilization, additional variables should be considered.

• 한국진공학회지
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• 제16권2호
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• pp.153-159
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• 2007

KSTAR 장치의 저온 component에 헬륨을 공급하기 위한 헬륨라인은 크게 두 가지로 이루어져 있다. 냉동기에서 KSTAR 저온용기 외부까지의 트랜스퍼 라인과, 저온용기 내부의 헬륨라인이다. KSTAR 장치는 3가지 종류의 헬륨을 사용하여 각 저온 component를 냉각하는데, 초전도 자석 시스템과 버스라인에는 초임계 헬륨, 전류인입장치에는 액체 헬륨, 열차폐체에는 가스 헬륨을 공급한다. 저온용기 내부의 헬륨라인은 냉동기에서 저온용기 근처까지 연결된 배관을 저온용기 내부의 각 장치에 최단거리로 열손실 없이 설치하여 각 장치가 정상 작동하도록 하는데 그 목적이 있다. 저온용기 내부의 헬륨라인은 최대 20bar로 가압되는 운전시간 동안에 헬륨누설 없이 설치되어야 한다. 그리고 상온으로 부터의 복사열을 차단하기 위하여 다층절연제로 배관을 감싸주어야 하고 고전압 부분은 프리프레그 테잎으로 절연되어야 한다. 전기절연체는 세라믹과 스테인레스 스틸 튜브를 브레이징 접합 방법으로 연결하여 만들어진 것으론 배관과 배관, 배관과 저온 component간의 절연을 위해 사용되고, 헬륨라인과 동일하게 4.5K 초임계 헬륨온도에서 누설이 없어야 한다. 따라서 모든 전기절연체는 액체질소에 침전시켜 열충격을 가하고, 내부에 30 bar를 가압하여 진공 누설시험을 한다. 그리고 초전도 자석과 배관의 절연체로 사용되므로 15kV 고전압 절연 검사를 한다. 전기절연체의 세라믹 부분은 구조적 보강을 위하여 추가적으로 표면에 절연 작업을 한다. 현재 대부분의 저온용기 내부의 헬륨 라인은 설치 완료되어 있으며, 최종 검사가 진행 중이다.

• Journal of Korean Neurosurgical Society
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• 제30권5호
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• pp.575-580
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• 2001

Purpose : In general, pineal region tumors are managed by using microsurgical approach or stereoctactic biopsy. However, in selected cases endoscopic approach to pineal lesions might prove to be as effective as microsurgery and less invasive. We report an alternative surgical strategy for managing certain patients with pineal neoplasms that allows treatment of the symptomatic hydrocephalus as well as tumor biopsy under direct vision in the same sitting. Materials and Methods : Twenty-two patients with pineal region tumors with associated hydrocephalus were treated in one session by endoscopic third ventriculostomy and endoscopic tumor biopsy at our institution from October 1996 to January 2000. All patients were retrospectively evaluated. Results : There was no operative mortality. There was one cause of significant bleeding during biopsy, but was controlled endoscopically, and the patient recovered completely without neurologic deficit resulting from intra-operative bleeding. The symptoms related to increased intracranial pressure(ICP) have resolved in all patients, and the need for a shunt is completely eliminated. Histological diagnosis was achieved in 21 of the 22 patients by this procedure. A biopsy was not obtained in one patient. Although this pineal region tumor was seen endoscopically, this could not be biopsied because of technical difficulties in working around an enlarged massa intermedia. The lesions included fourteen germinomas, three mixed germ cell tumors, and one each of the followings: pineocytoma, pineoblastoma, pineocytoma/pineoblastoma(intermediate type), meningioma, and low grade glioma. Five of the 22 patients subsequently underwent formal microsurgical tumor removal. Additional chemotherapy or radiotherapy could then be initiated according to the histological diagnosis. Conclusion : We consider that endoscopy affords a minimally invasive way of reaching three objectives by one-step surgery in the management of pineal region tumors with associated hydrocephalus : 1) cerebrospinal fluid(CSF) sample for analysis of tumour markers and cytology, 2) treatment of hydrocephalus by third ventriculostomy, and 3) several biopsy specimens can be obtained identifying tumors which will require further open surgery or adjuvant radiation and/or chemotherapy. However, complications and morbidities should be emphasized so as to be avoided with further technical experience.

• 대기
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• 제15권2호
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• pp.101-118
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• 2005

Atmospheric ozone changes temporally and spatially according to both anthropogenic and natural causes. It is essential to quantify the natural contributions to total ozone variations for the estimation of trend caused by anthropogenic processes. The aims of this study are to understand the intrinsic natural variability of long-term total ozone changes and to estimate more reliable ozone trend caused by anthropogenic ozone-depleting materials. For doing that, long-term time series for Seoul of monthly total ozone which were measured from both ground-based Dobson Spectrophotometer (Beck #124)(1985-2004) and satellite TOMS (1979-1984) are analyzed for selected period, after dividing the whole period (1979~2004) into two periods; the former period (1979~1991) and the latter period (1992~2004). In this study, ozone trends for the time series are calculated using multiple regression models with explanatory natural oscillations for the Arctic Oscillation(AO), North Atlantic Oscillation(NAO), North Pacific Oscillation(NPO), Pacific Decadal Oscillation(PDO), Quasi Biennial Oscillation(QBO), Southern Oscillation(SO), and Solar Cycle(SC) including tropopause pressure(TROPP). Using the developed models, more reliable anthropogenic ozone trend is estimated than previous studies that considered only QBO and SC as natural oscillations (eg; WMO, 1999). The quasi-anthropogenic ozone trend in Seoul is estimated to -0.12 %/decade during the whole period, -2.39 %/decade during the former period, and +0.10 %/decade during the latter period, respectively. Consequently, the net forcing mechanism of the natural oscillations on the ozone variability might be noticeably different in two time intervals with positive forcing for the former period (1979-1991) and negative forcing for the latter period (1992-2004). These results are also found to be consistent with those analyzed from the data observed at ground stations (Sapporo, Tateno) of Japan. In addition, the recent trend analyses for Seoul show positive change-in-trend estimates of +0.75 %/decade since 1997 relative to negative trend of -1.49 %/decade existing prior to 1997, showing -0.74 %/decade for the recent 8-year period since 1997. Also, additional supporting evidence for a slowdown in ozone depletion in the upper stratosphere has been obtained by Newchurch et al.(2003).

• 대기
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• 제26권4호
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• pp.617-633
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• 2016

Jangbogo station is located in Terra Nova Bay over the East Antarctica, which is often affected by individual storms moving along nearby storm tracks and a katabatic flow from the continental interior towards the coast. A numerical simulation for two strong wind events of maximum instantaneous wind speed ($41.17m\;s^{-1}$) and daily mean wind speed ($23.92m\;s^{-1}$) at Jangbogo station are conducted using the polar-optimized version of Weather Research and Forecasting model (Polar WRF). Verifying model results from 3 km grid resolution simulation against AWS observation at Jangbogo station, the case of maximum instantaneous wind speed is relatively simulated well with high skill in wind with a bias of $-3.3m\;s^{-1}$ and standard deviation of $5.4m\;s^{-1}$. The case of maximum daily mean wind speed showed comparatively lower accuracy for the simulation of wind speed with a bias of -7.0 m/s and standard deviation of $8.6m\;s^{-1}$. From the analysis, it is revealed that the each case has different origins for strong wind. The highest maximum instantaneous wind case is caused by the approach of the strong synoptic low pressure system moving toward Terra Nova Bay from North and the other daily wind maximum speed case is mainly caused by the katabatic flow from the interiors of Terra Nova Bay towards the coast. Our evaluation suggests that the Polar WRF can be used as a useful dynamic downscaling tool for the simulation and investigation of high wind events at Jangbogo station. However, additional efforts in utilizing the high resolution terrain is required to reduce the simulation error of high wind mainly caused by katabatic flow, which is received a lot of influence of the surrounding terrain.

• Archives of Plastic Surgery
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• 제36권3호
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• pp.351-355
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• 2009

Purpose: Cervical necrotizing fasciitis tends to involve the deep soft tissues and spread caudally to the anterior chest and mediastinum, often resulting in major complications and death. It may rapidly spread into the thorax along fascial planes, and the associated diagnostic delay results in this descending necrotizing mediastinitis. So, aggressive multidisciplinary therapy with surgical drainage is mandatory. We present a very rare case of descending necrotizing mediastinitis with literature review. Methods: A 53 years old male visited our department 7 days after trauma in neck. His premorbid conditions and risk factors of necrotizing fasciitis were concealed hepatoma, trauma history, chronic liver disease, and nutrition deficit. Computed tomographic scans of the head and neck region were performed in this patient : signs of necrotizing fasciitis, were seen in the platysma, sternocleidomastoid, trapezius muscle and strap muscles of the neck. Fluid accumulations involved multiple neck spaces and mediastinum. At the time, he diagnosed as necrotizing fasciitis on his neck and anterior chest. Necrotic wound was excised serially and we treated this with the Vacuum - assisted closure(VAC, Kinetics Concepts International, San Antonio, Texas) system device. After appropriately shaping the sponge and achieving additional 3 pieces drainage tubes in the pockets, continuous negative pressure of 125 mmHg was applied. The VAC therapy was utilized for a period of 12 days. Results: We obtained satisfactory results from wide excision, abscess drainage with the VAC system, and then split thickness skin graft. The postoperative course was uneventful. Conclusion: The refined technique using the VAC system can provide a means of simple and effective management for the descending necrotizing mediastinitis, with better cosmetic and functional results. Finally, the VAC system has been adopted as the standard treatment for deep cervical and mediastinal wound infections as a result of the excellent clinical outcome.

• 대한기계학회논문집B
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• 제35권5호
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• pp.473-480
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• 2011

막 가습기는 다른 가습장치와는 달리, 기생 전력의 손실이 없고 가습 성능이 우수하여 이온교환막 연료전지의 외부 가습을 위해 적용되고 있다. 원통형 막 가습기는 특히 가습성능에 비해 요구 체적이 매우 작기 때문에, 수송용 및 가정용 이온교환막 연료전지에 적용된다. 막가습기의 최적 설계를 위한 열 및 물질 전달 특성에 대한 이해가 필요하지만, 아직 다양한 연구가 이루어지고 있지 않다. 본 연구에서는 원통형 막가습기의 열 및 물질전달 특성을 이해하기 위한 특성 실험을 수행하였다. 기존의 습도 측정계는 비정상 가습 특성 실험에 한계가 있고, 정상 상태에서도 고온 다습한 환경에서는 오차가 크기 때문에 본 연구에서는 습증기 응축법을 이용하였다. 가습기의 정상상태 특성을 확인하기 위해 압력과 온도 변화에 대한 실험을 수행하였으며, 비정상 특성을 확인하기 위해 순간 유량 변화 시의 가습 성능을 측정하였다. 본 연구에서는 이상의 기초 실험을 통해서 막 가습기의 성능에 영향을 미치는 주요 인자를 확인하였으며, 원통형 막가습기의 기초적인 열 및 물질 전달 특성을 이해하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2001년도 추계학술강연 및 발표대회
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• pp.7-7
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• 2001

The increasing interest in light weight materials coupled to the need for cost -effective processing have combined to create a significant opportunity for aluminum P/M. particularly in the automotive industry in order to reduce fuel emissions and improve fuel economy at affordable prices. Additional potential markets for Al PIM parts include hand tools. Where moving parts against gravity represents a challenge; and office machinery, where reciprocating forces are important. Aluminum PIM adds light weight, high compressibility. low sintering temperatures. easy machinability and good corrosion resistance to all advantages of conventional iron bm;ed P/rv1. Current commercial alloys are pre-mixed of either the AI-Si-Mg or AL-Cu-Mg-Si type and contain 1.5% ethylene bis-stearamide as an internal lubricant. The powder is compacted in closed dies at pressure of 200-500Mpa and sintered in nitrogen at temperatures between $580~630^{\circ}C$ in continuous muffle furnace. For some applications no further processing is required. although most applications require one or more secondary operations such as sizing and finishing. These sccondary operations improve the dimension. properties or appearance of the finished part. Aluminum is often considered difficult to sinter because of the presence of a stable surface oxide film. Removal of the oxide in iron and copper based is usually achieved through the use of reducing atmospheres. such as hydrogen or dissociated ammonia. In aluminum. this occurs in the solid st,lte through the partial reduction of the aluminum by magncsium to form spinel. This exposcs the underlying metal and facilitates sintering. It has recently been shown that < 0.2% Mg is all that is required. It is noteworthy that most aluminum pre-mixes contain at least 0.5% Mg. The sintering of aluminum alloys can be further enhanced by selective microalloying. Just 100ppm pf tin chnnges the liquid phase sintering kinetics of the 2xxx alloys to produce a tensile strength of 375Mpa. an increilse of nearly 20% over the unmodified alloy. The ductility is unnffected. A similar but different effect occurs by the addition of 100 ppm of Pb to 7xxx alloys. The lend changes the wetting characteristics of the sintering liquid which serves to increase the tensile strength to 440 Mpa. a 40% increase over unmodified aIloys. Current research is predominantly aimed at the development of metal matrix composites. which have a high specific modulus. good wear resistance and a tailorable coefficient of thermal expnnsion. By controlling particle clustering and by engineering the ceramic/matrix interface in order to enhance sintering. very attractive properties can be achicved in the ns-sintered state. I\t an ils-sintered density ilpproaching 99%. these new experimental alloys hnve a modulus of 130 Gpa and an ultimate tensile strength of 212 Mpa in the T4 temper. In contest. unreinforcecl aluminum has a modulus of just 70 Gpa.

• The Korean Journal of Pain
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• 제14권1호
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• pp.61-67
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• 2001

Background: Usually, lumbar epidural block is performed on the $L_{3-4}$ interspace. This study was designed to evaluate the analgesic efficacy and shortening of labor duration comparing the $L_{1-2}$ and $L_{3-4}$ interspace epidural blocks in nulliparous normal vaginal deliveries and then investigates side effects following the blocks. Methods: Eighty healthy nulliparous women were divided into two groups, $L_{1-2}$ (n = 40) and $L_{3-4}$ (n = 40). Epidural blocks, lumbar epidural block were performed at the $L_{1-2}$ and $L_{3-4}$ interspace with a catheter advancing 3 cm cephalad. The initial dose of 12 ml (0.167% bupivacaine, fentanyl $50{\mu}g$ and clonidine $75{\mu}g$) was injected epidurally at 4 cm dilatation of cervix and severe pain of labor. If a visual analogue scale (VAS) score was more than 4 points, an additional dose was administered epidurally using the same volume as the above mentioned, but with the exception that the bupivacaine was diluted to 0.1 percentage. The maternal blood pressure, pulse rate, respiration rate and fetal heart rate were measured at 10 min intervals for the first 30 min, at 15 min interval for the next 30 min and at 30 min interval for the last one hour following the blocks. The duration of the first (active) and second stages of labor was counted and the neonatal Apgar score was recorded at one and five min after delivery. The degree of motor block, pruritus, nausea and vomiting were also noted. Results: The patients in group $L_{1-2}$ had lower pain scores than group $L_{3-4}$ at 5, 20, 30, 60 mins. The duration of 1st and 2nd labor stage in the $L_{3-4}$ epidural block were $272{\pm}33.5$ min, $49.2{\pm}27.4$ min respectively but those in the $L_{1-2}$ epidural block were $253.5{\pm}32.5$ min, $37.3{\pm}22.3$ min, respectively. Conclusions: We concluded the analgesic efficacy and shortening of labor duration in $L_{1-2}$ epidural block was better than those in $L_{3-4}$ epidural block. Maternal hemodynamic change, motor block. pruritus, nausea, vomiting and Apgar score showed no significant differences between the two groups.

• 에너지공학
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• 제21권4호
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• pp.402-410
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• 2012

본 연구에서는 가솔린 엔진 자동차에서 엔진 폐열 회수를 위한 이중 회로 랭킨 사이클 성능 해석이 수행되었다. 고온(HT)의 엔진 배기가스 열회수를 위해서는 물을 사용하는 스팀사이클이 적용되었고, 엔진 냉각수열과 고온 사이클로부터의 응축열을 활용하는 저온(LT) 사이클은 R-134a를 사용하는 유기랭킨사이클이 적용되었다. 고온 및 저온 열원을 동시에 활용하는 이중 회로 시스템의 특성을 파악하기 위해 에너지 및 엑서지 분석이 수행되었다. 고온 및 저온 사이클에 사용되는 용적형 팽창기의 체적이 차량적용을 위한 시스템 최적화에 매우 중요하며 시스템 최적화를 위해서는 반드시 고려되어야 한다. 목표로 하는 엔진 운전 조건에서 고온(HT) 팽창기와 저온(LT) 팽창기의 체적을 고려하면서 고온(HT) 사이클의 팽창비와 저온(LT) 사이클의 응축온도가 시스템의 성능에 미치는 영향을 파악하였다. 본 연구에서는 이러한 이중 회로 랭킨 사이클 시스템에 의해 목표 엔진 운전조건에서 엔진 폐열로부터 약 21%의 추가 동력을 얻을 수 있는 것으로 예측되었다.