• 한국정보통신학회논문지
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• 제5권2호
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• pp.309-313
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• 2001

본 논문에서는 Custom Power 응용을 위한 전압 안정화 특성을 갖는 다기능 3상 전자식 강압형 변압기가 제안된다. 제안된 전자식 변압기는 다음과 같은 특징을 갖는다. 1) 무게가 1㎾ 기준 일반 변압기의 40% 수준이다. 2) PWM 제어에 의하여 입력전압의 변동에 무관한 출력전압을 유지하는 전압 안정화 기능을 갖는다 3) 전원 또는 부하단의 Emergency에 대하여 회로 차단기의 기능도 갖는다. 4) 부하에 최초 전원 공급시, 낮은 전압으로부터 점진적으로 증가시켜가면서 전원을 인가하여, 전원 투입시 발생할 수 있는 돌입전류나 과도 충격을 제거할 수 있다. 그 밖에 무부하시 전원차단 기능과, 왜곡된 입력전압에 대한 보상기능을 추가 할 수 있다. 본 논문에서는 제안된 강압형 전자식 변압기의 회로 구성과 특징을 설명하고, 이를 PSPICE 시뮬레이션을 통하여 동작특성을 보인다.

• Journal of Periodontal and Implant Science
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• 제41권4호
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• pp.192-200
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• 2011

Purpose: The aim of this study is to compare the gene expression profile in mesenchymal stem cells derived from dental tissues and bone marrow for characterization of dental stem cells. Methods: We employed GeneChip analysis to the expression levels of approximately 32,321 kinds of transcripts in 5 samples of bone-marrow-derived mesenchymal stem cells (BMSCs) (n=1), periodontal ligament stem cells (PDLSCs) (n=2), and dental pulp stem cells (DPSCs) (n=2). Each cell was sorted by a FACS Vantage Sorter using immunocytochemical staining of the early mesenchymal stem cell surface marker STRO-1 before the microarray analysis. Results: We identified 379 up-regulated and 133 down-regulated transcripts in BMSCs, 68 up-regulated and 64 down-regulated transcripts in PDLSCs, and 218 up-regulated and 231 down-regulated transcripts in DPSCs. In addition, anatomical structure development and anatomical structure morphogenesis gene ontology (GO) terms were over-represented in all three different mesenchymal stem cells and GO terms related to blood vessels, and neurons were over-represented only in DPSCs. Conclusions: This study demonstrated the genome-wide gene expression patterns of STRO-$1^+$ mesenchymal stem cells derived from dental tissues and bone marrow. The differences among the expression profiles of BMSCs, PDLSCs, and DPSCs were shown, and 999 candidate genes were found to be definitely up- or down-regulated. In addition, GOstat analyses of regulated gene products provided over-represented GO classes. These data provide a first step for discovering molecules key to the characteristics of dental stem cells.

• Journal of Welding and Joining
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• 제34권6호
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• pp.62-68
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• 2016

Laser welding has superior characteristic such as low distortion, high welding speed, easy automation and real time control. But it is easy to occur weld defects such as porosity, crater, humping bead in the area of welding start and end. These weld defects can be suppressed by applying the wave shape control. In this study CW fiber laser was used for welding of $0.5mm^t$ pure titanium. Penetration properties were evaluated with the time of slope up and down. After then the bead shape was observed, and the maximum depth and the area of crater were measured. The bead shape of welding start area changed to be sharp with increase of slope up time and non-weld area of welding start increased. The crater and humping bead were suppressed with slope down time. The cooling rate of crater area was understood through measure of the hardness. Also, The distribution tendency of alloying elements was observed by EPMA and EDS. When wave shape control didn't applied to weld, the hardness of end weld increased due to rapid cooling rate and the hardness of rear part in the crater was higher than that of fore part. On the other hand, when the wave shape control was used for end weld, the increase of hardness in the end weld couldn't be found due to gradual cooling rate.

• 한국병원경영학회지
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• 제6권1호
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• pp.147-163
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• 2001

The purpose of this study was to find out the restructuring strategy for five provincial hospitals through the business analysis and survey of the service area. Through the survey of the service area of 5 hospitals. service area was classified into three groups, such as underserved area, adequate area, and overserved area. The strategy for the restructuring the clinical departments was set up based on the result of the business analysis and characteristics of the service area. The result of the study was as follows; 1) Whether or not a provincial hospital has specialized in specific area according to the circumstances and the needs of the community was the major factor influencing on the operating result of the hospital. 2) Provincial hospitals at the underserved area has to invest according to the changes of the occupancy rate and increasing pattern of the number of patients while maintaining the status as a general hospital. 3) Provincial hospitals at the adequate area has to lower the grade from the general hospital down to the hospital first and has to upgrade the competency through the restructuring the clinical departments and investment in specific area. 4) Provincial hospitals at the overserved area has to lower the grade from the general hospital down to the hospital first and has to seek ways to change the hospital fundamentally into geriatric hospital, pneumoconiosis hospital or psychiatric hospital etc. Provincial hospitals incapable to compete with private hospitals and clinics has to lower the grade from the general hospital down to the hospital first, to specialize in specific area and to restructure some clinical departments into rental base or self-operating basis. In case such methods are judged not so good solution, provincial hospitals has to find out ways such as shut-down of several departments or operating under the attending system.

• Archives of Pharmacal Research
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• 제10권4호
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• pp.212-218
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• 1987

Intact brain cell aggregates were dissociated from adult rat brains without cerebellum using a sieving technique. This proparation was used to elucidate the binding characteristics of agonist to muscarinic acetylcholine receptors (mAchR) in brain. Incubation of cells with carbamylcholine (carbachol) was shown agonist-induced receptor down-regulation depending on the concentration of agonist, not depending on the incubation time. This effect of carbachol was due to a reduction in the maximal binding capacity ($B_{max}$) to the mAchR without decreasing the affinity of the remaining receptors in incubation at 37.deg.C but was not apparent inincubation at $15^{\circ}}C$In addition, it was abolished when the receptors were blocked by atropine. The decline in ($^3H$)N-methylscopolamine (($^3H$)NMS) binding induced by agonist was reflected as a significant reduction in the receptor density with no change in receptor affinity, suggesting that 'true' receptor down-regulation takes place. Moreover, when the receptors were labeled with the lipophilic antagonist ($^3H$) quinuclidinyl benzilate (($^3H$) QNB) insted of the hydrophilic ligand ($^3H$)NMS, the magnitude of the observed receptor down-regulation was significantly lower in case of the former than the latter. This suggested that exposure of intact brain cells to muscarinic agonists might induce a slight degree of accumulation of receptors in intracellular sites before the receptors are actually degraded.

• 한국콘텐츠학회논문지
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• 제20권5호
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• pp.251-260
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• 2020

<인셉션>에서 음악은 꿈속 공간들의 통로가 되는 동시에 시간속도가 서로 다른 공간 사이에서 시간성의 문제를 낳는다. 본 논문은 이 음악의 시간성을 베르그손의 시간개념을 통해 고찰하는 데 목적이 있다. 영화에서 사용된 음악《Non, je ne regrette rien》은 원곡 버전과 템포를 늦춘 버전, 그리고 느려진 템포를 골격으로 재편곡된 버전으로 나누어지며, 본 연구는 실제적 분석을 통해 그 특징과 유사도를 시각적으로 확인하였다. 베르그손의 지각과 기억 도식의 관점에서, 디제시스의 잠재태적 음악(템포를 늦춘 버전)이 내재하는 비디제시스의 현실태적 음악(재편곡된 버전)은 영화음악과 음악신호의 역할을 동시에 수행하고 있다. 또한 원곡 버전과 템포를 늦춘 버전은 질적 변화를 갖는 지속하는 동일체의 관계로서, 우리는 역원뿔 도식 내의 위치를 살펴보고, 이 둘의 관계를 도식에 응용해 보았다. <인셉션>의 다층구조에서 생기는 음악의 시간성을 현재와 과거가 공존하는 베르그손의 철학에 근거하여 탐구한 것은 본 연구의 큰 성과라 할 수 있다.

• International Journal of Precision Engineering and Manufacturing
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• 제4권3호
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• pp.62-67
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• 2003

The grinding force generated during the grinding process causes an elastic deformation of the workpiece, grinding wheel, and machine system. Thus, the true depth of cut is always smaller than the apparent depth of cut. This is known as machining elasticity phenomenon. The machining elasticity parameter is defined as a ratio between the true depth of cut and the apparent depth of cut. It is an important factor to understand the material removal mechanism of the grinding process. To increase productivity, the value of this machining elasticity parameter must be large. Therefore, it is essential to know the characteristics of this parameter. The objective of this research is to study the effect of the major grinding conditions, such as table speed, depth of cut, on this parameter experimentally, Through this research, it is found that this parameter value is increasing when the table speed is decreasing or the depth of cut is increasing. Also, this parameter value depends on the grinding mode (up grinding, down grinding).

• Molecules and Cells
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• 제28권6호
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• pp.565-573
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• 2009

The pig could be a useful model to characterize molecular aspects determining several delicate phenotypes because they have been bred for those characteristics. The Korean native pig (KNP) is a regional breed in Korea that was characterized by relatively high intramuscular fat content and reddish meat color compared to other western breeds such as Yorkshire (YS). YS grew faster and contained more lean muscle than KNP. We compared the KNP to Yorksire to find molecular clues determining muscle characteristics. The comparison of skeletal gene expression profiles between these two breeds showed molecular differences in muscle. We found 82 differentially expressed genes (DEGs) defined by fold change (more than 1.5 fold difference) and statistical significance (within 5% of false discovery rate). Functional analyses of these DEGs indicated up-regulation of most genes involved in cell cycle arrest, down-regulation of most genes involved in cellular differentiation and its inhibition, down-regulation of most genes encoding component of muscular-structural system, and up-regulation of most genes involved in diverse metabolism in KNP. Especially, DEGs in above-mentioned categories included a large number of genes encoding proteins directly or indirectly involved in p53 pathway. Our results indicated a possible role of p53 to determine muscle characteristics between these two breeds.

• Journal of Trauma and Injury
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• 제23권2호
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• pp.96-101
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• 2010

Purpose: This study was conducted in order to evaluate the epidemiological characteristics of?children with fall-down injuries according to age groups and to analyze the major trauma groups that were treated at the emergency room (ER). Methods: Among 1,222 children under age 6 who were treated at the ER from January 2008 to December 2009, a retrospective study was conducted through examination of medical records. The children were classified by age into 3 groups: infant, toddler, and pre-schooler. In each group, the differences between the causative factors that led to the fall-down injuries were analyzed. Also, ISS (Injury Severity Score) score above 4 was classified as major trauma, and an ISS score 0-1 was classified as a minor trauma. The relationship between major trauma and age group was also analyzed. Results: Through an analysis of child fall-down injuries, men (56.6%), toddler (47.3%), head-related symptoms (72.9%), furniture-related traumas (80.2%), and falls from less than a 1-m height (69.9%) were found to be common factors. Furthermore, in radiological studies, fractures and brain hemorrhages accounted for 16.9% of major traumas, and simple skull fractures were the most common (21.4%). Distributed according to age group, the factors relevant to fall injuries were fall height and head-related symptoms for infants, accident site, fall height and head-related symptoms for toddlers, and accident site for pre-schoolers (p<0.05). Also, headrelated symptoms and fall height were independent factors of major trauma in all age groups. However, major traumas (17.3%) were related to dumped trauma, fall height and accident site (p<0.05). Conclusion: This study was mainly about head-related injuries, and toddler were most common victims. The relevant factors for the major trauma were falling height for infants, accident site and falling height for toddlers, and accident site, falling height for pre-schoolers.

• 한국주거학회논문집
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• 제13권2호
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• pp.65-71
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• 2002

Recently, the space organization of Korean-Chinese houses is different from that of other territories. The characteristics of eating and dinning space for Korean-Chinese Multi-family Housing are as follows ; ⅰ) The most obvious change in Korean-Chinese urban housing style was seen in kitchen space, which can be classify three types such as traditional type, improved type, and LDK type on the bases of heating and cooking method. ⅱ) Special feature of Korean-Chinese housing in Yanji city was that kitchen fulfilled important functions such as heating, cooking, dinning, sleeping, bathing and washing. Since then, each function was separated and functions of kitchen were cut down after all. iii) The arrangement of kitchen space have changeed according to the change of heating fuel, heating system, equipment, relatcd policy, etx. Multi-function kitchen discovered only in Yanji had lasted until 1980's by equipping heating floor system, which is suitable for sit-down living style. In 1990's, this kitchen style was prohibited legally, and the balcony area of kitchen widened due to the abolition of outdoor storehouse for foodstuff.