• 한국안전학회지
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• 제26권4호
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• pp.41-46
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• 2011

The purpose of this paper is to analyze the causes of accidents related to the 3 phase 170 kV gas insulated switchgear of a power system collected from accident sites to secure data for the prevention of similar accidents and provide important points of view regarding diagnosis for the prevention of accidents involving gas insulated switchgears. The analysis results of the causes of accidents involving gas insulated switchgears showed deformation of the manipulation lever installed at the S-phase, disconnection of the insulation rod connection, melting of the upper conductor, a damaged tulip, damage to the lower spacer and the spacer at the breaker, etc. It is believed from this result that the potential for accidents has expanded due to accumulated energy as a result of repeated deterioration. The carbonization depth of a GIS was formed near the screw (T2, T3) used to secure the lower pole of the S-phase tulip. It is not known what has caused the screws to be extruded and melted. However, it is thought that an unbalanced electromagnetic force, micro-discharge, surface discharge, etc., have occurred at that point. In addition, even though 16 years have passed since its installation, there was no installation defect, act of arson, accidental fire, etc. General periodical inspection and diagnosis failed to find the factors causing the accidents. As a system contained in a closed metal container, it has a high risk factor. Therefore, it is necessary to design, install and operate a GIS in accordance with the standard operational procedure (SOP). In addition, it is necessary to apply conversion technology for periodical SF6 gas analysis and precision safety diagnosis. It is expected that tracking and managing these changes in characteristics by recording the results on the history card will provide a significant accident prevention effect.

• 한국전기전자재료학회논문지
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• 제33권6호
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• pp.490-494
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• 2020

Sulphur hexafluoride (SF₆) is mostly used as a current-insulating medium in gas-insulated switchgears (GIS), owing to its excellent dielectric strength and arc-extinguishing performance. The global warming potential (GWP) of SF₆, however, is 23,900 times that of CO₂, and its life time in the atmosphere is 3,200 years. For these reasons, new eco-friendly gases to replace SF₆ are required. In this study, the partial discharge (PD) characteristics of green gas for grid (g³) and dry air (N₂/O₂) were analyzed to compare with those of SF₆. A PD electrode system was designed to simulate the protrusion defect in GISs and fabricated for experimentation. To compare the PD characteristics of each gas, the discharge inception voltage (DIV), discharge extinction voltage (DEV), discharge magnitude, discharge pulse number, and phase pattern were analyzed. Results from this study are expected to provide fundamental materials for the design of eco-friendly GISs.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3532-3536
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• 2012

난자 세포의 정상적인 성숙과정을 이해하려면 모계유래 유전자 발현 증가의 분자 생물학적 기전을 밝혀내야 한다. 이것은 모계 유전자의 염기서열의 변화와 밀접한 관계가 있다. 전 연구결과에 의하면 돼지 난자 체외 성숙과정에서의 모계 유전자 mRNA 발현은 통상적으로 poly(A) 꼬리 길이와 아데닐산 중합반응에 의하여 검증된다. 하지만 포유동물 체외성숙 과정에서는 아직까지 밝혀진 것이 없다. 따라서 본 연구목적은 성숙단계 난모세포에서의 분자생물학적 기전을 해명하고자, 4개의 중요한 모계유전자발현을 real-time PCR기법으로 확인하여 poly(A) 꼬리 길이와 아데닐산중합반응의 변화를 확인하였다. 본 연구에서 접합체 유전자 활성화 단계에서 모계 유전자의 비정상적인 발현과 이것에 상응하는 단백질 수준의 억제는 일부 혹은 대부분 유전자 손실에 의하여 초래된 것임을 알 수 있었다. 따라서 이상적인 모계 유전자 발현은 난자 세포의 성숙 및 더 나가서 초기 배아 발달에 중요한 역할을 하는 것임을 확인 하였다.

• Journal of Korean Neurosurgical Society
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• 제38권6호
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• pp.435-441
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• 2005

Objective : Expandable cage used for spinal reconstruction after corpectomy has several advantages over nonexpendable cages. Here we present our clinical experience with the use of this cage after anterior column corpectomy with an average of one year follow up. Methods : Ten patients underwent expandable cage reconstruction of the anterior column after single-level or multilevel corpectomy for various cervical spinal disorders. Anterior plating with or without additional posterior instrumentation were performed in all patients. Functional outcomes, complications, and radiographic outcomes were determined. Results : There was no cage-related complication. Functionally, neurological examination revealed improvement in 7 of 10 patients and no patient had neurological deterioration after the surgery. Immediate stability was achieved and maintained throughout the period of follow-up. There was minimal subsidence [<2mm] noticeable in three of the cases that underwent a two-level corpectomy. Subsidence was noted in osteoporotic patients and patients undergoing multi-level corpectomies. Average pre-operative kyphotic angle was 9 degrees. This was corrected to an average of 5.4 degrees in lordosis postoperatively. Conclusion : In conclusion, expandable cages are safe and effective devices for vertebral body replacement after cervical corpectomy when used in combination with anterior plating with or without additional posterior stabilization. The advantages of using expandable cages include its ability to easily accommodate itself into the corpectomy defect, its ability to tightly purchase into the end plates after expansion and thus minimizing the potential for migration, and finally, its ability to correct kyphosis deformity via its in vivo expansion properties.

• Journal of Yeungnam Medical Science
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• 제6권1호
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• pp.171-178
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• 1989

저자들은 영남대학병원에 입원한 52세 남자환자로서 임상소견, 조직소견, 근전도 소견상으로 소세포폐암과 동반된 Eaton-Lambert 증후군으로 진단된 1례를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• 전기전자학회논문지
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• 제25권3호
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• pp.578-583
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• 2021

본 논문에서는 반도체의 신뢰성을 테스트하기 위한 가속 시험에 대해 설명하고 자동차 반도체의 신뢰성 테스트 국제 표준인 AEC-Q100에 대해 다룬다. 반도체는 수십년 동안 사용할 수 있기 때문에 수명 전주기에서 발생하는 잠재적인 문제점을 테스트하기 위해서는 집중적으로 스트레스를 가하여 테스트 시간을 최소화하는 가속 시험이 필수적이다. 자동차 반도체에서 사용하는 대표적인 가속 시험인 AEC-Q100은 반도체에서 발생하는 각종 불량과 그 원인을 분석할 수 있도록 설계되었기 때문에 반도체의 수명과 신뢰성을 예측할 수 있을 뿐만 아니라 설계상, 제조상의 문제도 쉽게 찾아낼 수 있다. AEC-Q100은 가속 스트레스 시험, 가속 수명 시험, 패키지 적합성 시험, 공정 신뢰성 시험, 전기적 특성 시험, 결함 검출 시험, 기계적 특성 시험의 7개 테스트 그룹으로 구성되며 동작 온도에 따라 Grade 0에서 Grade 3까지 4개의 등급이 존재한다. 반도체 소자, 광전자 반도체, 센서 반도체, 멀티 칩 모듈, 수동 소자 분야에서는 각각 AEC-Q101, Q102, Q103, Q104, Q200이 사용된다.

• Clinical and Experimental Reproductive Medicine
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• 제46권2호
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• pp.67-75
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• 2019

Objective: Sperm cryopreservation has been widely used in assisted reproductive technology, as it offers great potential for the treatment of some types of male infertility. However, cryopreservation may result in changes in membrane lipid composition and acrosome status, as well as reductions in sperm motility and viability. This study aimed to evaluate sperm DNA fragmentation damage caused by conventional freezing using the sperm chromatin dispersion test. Methods: In total, 120 fresh human semen samples were frozen by conventional methods, using SpermFreeze Solution as a cryoprotectant. Routine semen analysis and a Halosperm test (using the Halosperm kit) were performed on each sample before freezing and after thawing. Semen parameters and sperm DNA fragmentation were compared between these groups. Results: There was a significant decrease in sperm progressive motility, viability, and normal morphology after conventional freezing (32.78%, 79.58%, and 3.87% vs. 16%, 55.99%, and 2.55%, respectively). The sperm head, midpiece, and tail defect rate increased slightly after freezing. Furthermore, the DNA fragmentation index (DFI) was significantly higher after thawing than before freezing (19.21% prior to freezing vs. 22.23% after thawing). Significant increases in the DFI after cryopreservation were observed in samples with both normal and abnormal motility and morphology, as well as in those with normal viability. Conclusion: Conventional freezing seems to damage some sperm parameters, in particular causing a reduction in sperm DNA integrity.

• Journal of Periodontal and Implant Science
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• 제51권2호
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• pp.100-113
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• 2021

Purpose: Previous studies have solely focused on fresh extraction sockets, whereas in clinical settings, alveolar sockets are commonly associated with chronic inflammation. Because the extent of tissue destruction varies depending on the origin and the severity of inflammation, infected alveolar sockets may display various configurations of their remaining soft and hard tissues following tooth extraction. The aim of this study was to classify infected alveolar sockets and to provide the appropriate treatment approaches. Methods: A proposed classification of extraction sockets with chronic inflammation was developed based upon the morphology of the bone defect and soft tissue at the time of tooth extraction. The prevalence of each type of the suggested classification was determined retrospectively in a cohort of patients who underwent, between 2011 and 2015, immediate bone grafting procedures (ridge preservation/augmentation) after tooth extractions at Seoul National University Dental Hospital. Results: The extraction sockets were classified into 5 types: type I, type II, type III, type IV (A & B), and type V. In this system, the severity of bone and soft tissue breakdown increases from type I to type V, while the reconstruction potential and treatment predictability decrease according to the same sequence of socket types. The retrospective screening of the included extraction sites revealed that most of the sockets assigned to ridge preservation displayed features of type IV (86.87%). Conclusions: The present article classified different types of commonly observed infected sockets based on diverse levels of ridge destruction. Type IV sockets, featuring an advanced breakdown of alveolar bone, appear to be more frequent than the other socket types.

• 한국식품과학회지
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• 제54권2호
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• pp.241-246
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• 2022

본 연구는 S. aureus에 대한 tuberostemonine의 항균 및 항생물막 효과에 대하여 확인하였다. S. aureus에 대한 tuberostemonine의 생장 저해 효과가 없음을 확인하였으나, crystal violet 염색법과 CLSM 이미지 측정을 통해 tuberostemonine이 유의한 S. aureus 항생물막 효과 가지는 것을 알 수 있었다. S. aureus의 생물막 형성과 분해 관련 유전자인 icaA와 agrA의 발현은 tuberostemonine를 처리하였을 때 유의미하게 각각 감소 또는 증가하는 것으로 나타났다. 따라서 본 연구에서 생물막 형성 저해 및 분해 효과가 확인된 천연화합물인 tuberostemonine은 S. aureus의 내성 발생 위험이 적은 새로운 항생물막제제로서 사용가능 할 것으로 사료된다.

• Journal of Periodontal and Implant Science
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• 제52권4호
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• pp.312-324
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• 2022

Purpose: The role of hard-type crosslinked hyaluronic acid (HA) with particulate bone substitutes in bone regeneration for combined inlay-onlay grafts has not been fully investigated. We aimed to evaluate the effect of hard-type crosslinked HA used with bone substitute in terms of new bone formation and space maintenance. Methods: A 15-mm-diameter round defect was formed in the calvaria of 30 New Zealand White rabbits. All animals were randomly assigned to 1 of 3 groups: the control group (spontaneous healing without material, n=10), the biphasic calcium phosphate (BCP) graft group (BCP, n=10), and the BCP graft with HA group (BCP/HA, n=10). The animals were evaluated 4 and 12 weeks after surgery. Half of the animals from each group were sacrificed at 4 and 12 weeks after surgery. Samples were evaluated using micro-computed tomography, histology, and histomorphometry. Results: The BCP group showed higher bone volume/tissue volume (BV/TV) values than the control and BCP/HA groups at both 4 and 12 weeks. The BCP and BCP/HA groups showed higher bone surface/tissue volume (BS/TV) values than the control group at both 4 and 12 weeks. The BCP group showed higher BS/TV values than the control and BCP/HA groups at both 4 and 12 weeks. No statistically significant difference in newly formed bone was found among the 3 groups at 4 weeks. The BCP group showed significantly higher new bone formation than the BCP/HA group at 12 weeks. Conclusions: Hard-type crosslinked HA did not show a positive effect on new bone formation and space maintenance. The negative effect of hard-type crosslinked HA may be due to the physical properties of HA that impede osteogenic potential.