• 대한수의학회지
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• 제30권1호
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• pp.85-91
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• 1990

This study was designed in order to investigate the effect of copper sulfate to the ultrastructural changes of the hepatocytes in Sprague Dawley rats. The animals were administered with copper sulfate (10mg/kg B.W.), which was dissolved in normal saline. The solution was injected into abdominal cavity every day. The animals were sacrificed at the 6th, 12th, and 24th day from the beginning of administration. The specimens obtained from the liver were observed with electron microscope and significant changes were as follows. 1. A prominent dilatation and disruption of the cisternae of rough endoplasmic reticulum were recognized. Also, the detachment of membrane bound ribosomes was shown. 2. The proliferation of smooth endoplasmic reticulum and the depletion of glycogen particles were noted. 3. The increase of primary lysosomes and autophagic vacuoles was obserbed. 4. The dilatation of mitochondrial cristae was obserbed. And it was irregulary scattered in the stroma of mitochondria. 5. The atrophy of microvilli in the bile canaliculi and space of Disse was prominent. 6. Membrane of hepatocytes was damaged and significant hydrophic degeneration was obserbed in the perisinusoidal regions. 7. The damage of Fat-storing cells was more significant than that of hepatocytes.

• 한국분무공학회지
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• 제1권3호
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• pp.51-59
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• 1996

An experiment was carried out on the structure of twin spray from pressurize-swirl nozzles, in order to investigate the effect of different size of spray nozzles on the characteristics of the overlap of two single sprays, for example, mean diameter, number density, and spatial distribution of flow rate. Using image processing method, the distributions of size and velocity of droplets of a single spray and twin spray were measured and compared to investigate the overlapping effect of two identical sprays. Comparing experimental results from a twin-spray with those from two-single sprays shows that the flow rate distribution of the twin-spray was concentrated around the midst of the overlapping region of two sprays. In this region, Sauter mean diameter (SMD) did not change much in the twin spray from 6032 nozzles, but it was smaller by 10 micrometers in the twin-spray than two-single sprays from 60063 nozzles. In spite of large difference in Weber numbers of the colliding sprays between the 60063 and 6032 nozzles, the phenomena did not have a big change in the overlapping region of twin spray. This shows that in the collision between droplets from two single spray in the overlapping region to cause the disruption of droplets, the size distribution of spray droplets was also important as well as Weber number.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2000년도 국제심포지움
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• pp.3-4
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• 2000

The synthesis of acyl-CoA catalyzed by acyl-CoA synthetase (ACS, EC 6.2.1.3) from fatty acid, ATP, and CoA is a crucial reaction in mammalian fatty acid metabolism. In arachidonate metabolism, acyl-CoA synthetase(ACS) plays a key role in the esterification of free arachidonate into membrane phospholipids. Following its release by the action of calcium dependent phospholipase, free arachidonate is believed to be rapidly converted to arachidonoyl-CoA and reesterified into phospholipids in order to prevent excessive synthesis of eicosanoids. In previous studies, we have characterized five ACSs (designated as ACS1-5) with different tissue distribution. ACS1, ACS2, and ACS5 are similar in structure and fatty acid preference, and completely different from ACS3 and ACS4. The latter are arachidonate-preferring enzymes closely related in structure but expressed in different tissues: ACS3 mRNA is highly expressed in the brain and the mRNA for ACS4 is expressed in steroidogenic tissues including adrenal gland, ovary, and testis. To learn more about the potential function of ACS4 in arachidonate metabolism, we have produced knock-out mice for ACS4 gene. ACS4+/- females become pregnant less frequently and produce small litters with extremely low transmission of the disrupted alleles. Striking morphological changes including extremely enlarged uterine filled with numerous proliferative cysts of various size were detected in ACS4+/- females. Furthermore, marked accumulation of prostaglandins were seen in the uterus of heterozygous females. These results indicate that ACS4 is critical for the uterine arachidonate metabolism and heterozygous disruption of its gene lead to impaired pregnancy.

• 한국수정란이식학회지
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• 제28권2호
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• pp.95-111
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• 2013

Worldwide there is concern about the continuing release of a broad range of environmental endocrine disrupting chemicals, including polychlorinated biphenyls, dioxins, phthalates, polybrominated diphenyl ethers (PBDEs), and other halogenated organochlorines persistent organic pollutants (POPs) into the environment. They are condemned for health adverse effects such as cancer, reproductive defects, neurobehavioral abnormalities, endocrine and immunological toxicity. These effects can be elicited via a number of mechanisms among others include disruption of endocrine system, oxidation stress and epigenetic. However, most of the mechanisms are not clear, thus several number of studies are ongoing trying to elucidate them in order to protect the public by reducing these adverse effects. In this review, we briefly limited review the process, the impacts, and the potential mechanisms of dioxin/dioxin like compound, particularly, their possible roles in adverse developmental and reproductive processes, diseases, and gene expression and associated molecular pathways in cells.

• 한국위성정보통신학회논문지
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• 제12권1호
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• pp.13-17
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• 2017

본 논문에서는 본 논문에서는 GPS 주파수 블록 중 L1블록인 1.575GHz에서 동작하는 GPS 수신 안테나를 설계하였다. 기존 GPS 수신 안테나는 고정 광역빔으로 차량이나 탑재체에서 이동할 경우 빔의 적응성이 다소 떨어지는 단점을 보인다. 이를 보완하기 위하여 안테나의 이득을 높이고 전기적 위상을 조절해 빔을 조향할 수 있도록 하여 빔의 적응성이 생기도록 하였다. 설계한 안테나는 마이크로스트립 패치 안테나로서 방사소자를 배열형태로 확장하여 이득을 높이고 이에 CRLH 위상변위기를 결합하여 각 방사소자에 위상차 급전이 가능하도록 하였다. 또한 제시된 CRLH 위상변위기는 단일 모델에서 가변 C의 조정으로 여러 가지 위상출력이 가능하도록 설계하여 버랙터 다이오드와 결합시 실시간으로 빔을 조정할 수 있어 항 재밍 기능도 갖출 수 있음을 보였다.

• 한국지진공학회논문집
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• 제2권2호
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• pp.69-75
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• 1998

액체저장탱크 구조물은 지진에 의해 붕괴되는 경우 구조물의 파손 및 저장물의 손실에 의한 직접피해보다 파급효과(유독물질이나 오염물질의 유출로 지속적인 재산피해 및 환경파괴를 초래함)가 더욱 심각하므로 이러한 직, 간접적 피해를 최소화하기 위한 내진설계기준의 제정이 시급한 과제이다. 본 논문에서는 원통형 액체저장탱크의 내진설계기준을 마련하기 위한 기초작업으로 뉴질랜드지침과 오스트리아지침의 해석방법을 고찰하고, 수치해석 예의 결과를 비교하여 두 지침의 적용타당성 및 문제점을 제시하였다.

• 한국조리학회지
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• 제24권2호
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• pp.119-127
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• 2018

The purpose of this study is to investigate the contamination level of micro plastics in Korean mackerel and to investigate the detection method of micro plastics in fish. This study analyzed the detection and composition of micro plastics using natural mackerel and wild mackerel. 30% hydrogen peroxide and surfactant were added to GF/C filter paper in order to detect micro plastics in the sea. If micro plastics are exposed to the ocean for a long time, accumulation of heavy metals in the water will make pollutant bioaccumulation more serious. Microscopic consequences The risk to human health of plastics has already been studied by many researchers and the risks to human health already caused by marine microorganisms and zooplankton are becoming clear. The conclusion of this study is that there is a difference between the length and height of the mackerel when it is cooked from the standpoint of food in terms of practical implications. The conclusion of this study is that the probability of micro-plastic-contaminated mackerel to reach and be consumed by end-consumers is low in academic implications. Residual contaminants adsorbed on micro plastics are absorbed by digestive organs and cause disruption, and further research on micro plastics is needed in the future.

• Advances in pediatric surgery
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• 제2권2호
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• pp.88-93
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• 1996

A clinical analysis was made of 42 pilomatricoma in 34 children treated, from January 1980 to August 1996 at the Department of Pediatric Surgery, Hanyang University. The gender ratio was 13 to 21 with female preponderance. The average age at presentation was 7 years 3 months(range 8 months to 19 years old). The time average interval from onset to excision was 9.8 months. The predilection site was neck, upper extremities, face, trunk and lower extremities in the decreasing order of frequency. The masses were less than 3cm in diameter and there was no correlation between age at presentation and size of the mass. Of the six children with multiple lesions, two presented with multiple lesions initially and four presented with second lesion metachronously after excision of the primary lesions. Two girls had cysticercosis and von Recklinghausen's disease respectively in association with a pilomatricoma. All lesions were encapsulated subcutaneous masses which were clearly distinguished from surrounding tissue, and 4 of them had pigmentation, ulceration, skin disruption and hemorrhagic changes in the overlying skin. Microscopically the mass was composed of basophilic cells and eosinophilic shadow cells. Calcification, foreign body giant cell, ossification, focal cystic, inflammatory or necrotic changes were also seen.

• 천문학회보
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• 제42권1호
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• pp.49.1-49.1
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• 2017

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters (GCs). Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars, together with the winds and ejecta from low and intermediate mass asymptotic giant branch stars, are all locally retained in these less massive systems. We first applied these models to investigate the origin of super-helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the winds of massive stars can naturally reproduce the required helium enhancement (dY/dZ = 6) for the second generation stars. Disruption of these "building blocks" in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field. Interestingly, we also find that the observed Na-O anticorrelation in metal-poor GCs can be reproduced, when multiple episodes of starbursts are allowed to continue in these subsystems. Specific star formation history with decreasing time intervals between the stellar generations, however, is required to obtain this result, as would be expected from the orbital evolution of these subsystems in a proto-Galaxy. The "mass budget problem" is also much alleviated by our models without ad-hoc assumptions on star formation efficiency and initial mass function.

• 천문학회보
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• 제43권1호
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• pp.46.1-46.1
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• 2018

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters. Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars, together with the winds and ejecta from low and intermediate mass asymptotic-giant-branch stars, are all locally retained in these less massive systems. We find that the observed Na-O anti-correlations in metal-poor GCs can be reproduced when multiple episodes of starbursts are allowed to continue in these subsystems. A specific form of star formation history with decreasing time intervals between the stellar generations, however, is required to obtain this result, which is in good agreement with the parameters obtained from our stellar evolution models for the horizontal-branch. The "mass budget problem" is also much alleviated by our models without ad-hoc assumptions on star formation efficiency and initial mass function. We also applied these models to investigate the origin of super helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the winds of massive stars can naturally reproduce the required helium enhancement (dY/dZ = 6) for the second-generation stars. Disruption of proto-globular clusters in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field.