• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1541-1542
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• 2015

본 논문에서는 휴대용 IT 기기 및 EV, ESS 등 사용이 급증하고 있는 리튬 폴리머 배터리의 화재사고 원인 분석기법에 대하여 나타내었다. 사고 원인 분석기법은 사례분석을 통하여 외형 및 탄화패턴 분석을 통한 발화 추정위치로 외력에 의한 사고 및 내부 절연 열화에 의한 사고 원인 분석 등을 나타내었다. 사고원인 분석은 배터리 안전성 확보와 사고 재발 방지를 위한 대책 마련에 필수적인 기술로 향후 증가하는 제품사고에 대한 분석기법 개발에 기초연구로 활용하고자 한다. 본 논문에서 제시한 분석기술과 향후 내부 절연 열화 원인 분석 기법을 개발하여 리튬 계열 배터리에서 발생하는 사고에 대하여 정확한 원인 분석에 활용할 것이다.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.25.2-25.2
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• 2010

MIRIS는 과학기술위성 3호의 주 탑제체로 우주 및 지구의 적외선 관측을 위한 두 개의 카메라 시스템을 가지고 있으며 이를 위한 적외선 검출용 이미지 센서가 각각 장착되어 있다. 이미지 센서를 통해 검출된 이미지 데이터를 읽기 위해 고속의 데이터 처리가 요구되어 FPGA 구성방식으로 전용 제어기를 구성하였다. 우주 및 지구의 적외선 관측용 이미지 센서는 구성 및 동작방법이 달라 요구기능을 만족하는 각각의 전용 이미지 센서 제어기를 개발했다. FPGA를 이용한 이미지 센서 제어기에는 검출된 이미지를 읽기위한 센서 제어 신호발생기, 아날로그 이미지 신호를 디지털 정보로 변환하는 ADC 제어용 신호 발생기, ADC의 출력 신호를 고속의 직렬 통신선로로 출력 하는 기능 외에 동작 모드 및 동작 상태 입력용 DSP 인터페이스, 고속의 직렬 통신 선로에 MIRIS 상태정보 삽입 기능, 제어기의 기능을 원격지에서 확인 할 수 있는 이미지 패턴 생성기능 등을 가지고 있다. 특히, 이미지를 읽기 위한 동작 시에만 클록 주파수를 인가하는 방법으로 FPGA 내부 회로를 구성하여 전류의 소모량을 최소화 하였다.

• Fire Science and Engineering
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• v.30 no.6
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• pp.99-104
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• 2016

In animal and plant facilities, dust samples were collected from cattle sheds, pigsties and hen-houses, which have high proportion of electrical fires. The samples were diluted in distilled water and water resistivity was measured. Current measurements and tracking reappearance experiments were conducted using distilled water with dust samples. The analysis results were obtained to track the fire risks according to the dust resistivity. The highest value was the dust from cattle sheds followed in order by the dust of pigsties and hen-houses. In experiments measuring the temperature change and RMS current, the lower resistivity of water showed a significant trend of temperature and high amperage. In the tracking reappearance experiment with the lower resistivity water, the tracking speed was fast and the ignition time was shortened. This study investigated why each dust resistivity shows different results.

• Fire Science and Engineering
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• v.30 no.6
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• pp.71-77
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• 2016

The electrolyte of the capacitor in mobile phone chargers leaks to the power input terminal resulting in tracking on the PCB board to form a carbonized conductive path. As a result of structural analysis of the cause of the tracking, It occurred when the power input terminal and the PCB board were connected directly using the connector. The larger the amount of electrolyte leaked from the capacitor into the power input terminal, or the lower the height of the partition provided between the plug pins of the power input terminal, the higher the tracking occurrence rate. Accordingly, to lower the occurrence rate of tracking in the charger, it is necessary to provide a partition on the capacitor or increase the height of the partition provided on the power input terminal so that the leaked electrolyte does not flow to the power input terminal. In addition, the tracking occurrence rate will be reduced further if the shape of the PCB board touching ther power connection terminal is changed to ${\Pi}$.

• Animal cells and systems
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• v.1 no.1
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• pp.99-105
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• 1997

Using three species of Korean frogs (Rana dybowskii, R. rugosa and R. nigromaculata), the annual spermatogenic pattern, the seasonal changes in the steroidogenic competence, and responsiveness of testis to gonadotropins in terms of testosterone secretion in vitro were examined. The spermatogenic pattern of R. dybowskii was classified as a discontinuous type since spermatogenesis stops completely after spawning in late winter (February) until mid-summer (July). In contrast, the pattern of R. nigromaculata and R. rugosa was classified as a potent continuous type since sperm was always present in the seminiferous tubules all year round. In all three species, the levels of testicular testosterone and that of testosterone secreted by testis following in vitro culture were very low in late summer (August), but increased thereafter until winter (hibernation period). Interestingly, responsiveness of testis in vitro to gonadotropins in terms of testosterone secretion increased markedly in November (early hibernation period). Specifically, bullfrog LH was more effective than FSH in stimulating the secretion of testosterone by frog testis in vitro during hibernation period. This fact suggests that testosterone secretion by testis during hibernation is at least regulated by the pituitary gonadotropin rather than environmental factors. Taken together, the data presented here suggest that testicular cycles of three species of Korean frogs are closely linked to their females breeding cycles, and are eventually controlled by various environmental cues.

• Journal of Gastric Cancer
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• v.17 no.3
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• pp.204-211
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• 2017

Purpose: Recently, a nomogram predicting overall survival after gastric resection was developed and externally validated in Korea and Japan. However, this gastric cancer nomogram is derived from large-volume centers, and the applicability of the nomogram in smaller centers must be proven. The purpose of this study is to externally validate the gastric cancer nomogram using a dataset from a medium-volume center in Korea. Materials and Methods: We retrospectively analyzed 610 patients who underwent radical gastrectomy for gastric cancer from August 1, 2005 to December 31, 2011. Age, sex, number of metastatic lymph nodes (LNs), number of examined LNs, depth of invasion, and location of the tumor were investigated as variables for validation of the nomogram. Both discrimination and calibration of the nomogram were evaluated. Results: The discrimination was evaluated using Harrell's C-index. The Harrell's C-index was 0.83 and the discrimination of the gastric cancer nomogram was appropriate. Regarding calibration, the 95% confidence interval of predicted survival appeared to be on the ideal reference line except in the poorest survival group. However, we observed a tendency for actual survival to be constantly higher than predicted survival in this cohort. Conclusions: Although the discrimination power was good, actual survival was slightly higher than that predicted by the nomogram. This phenomenon might be explained by elongated life span in the recent patient cohort due to advances in adjuvant chemotherapy and improved nutritional status. Future gastric cancer nomograms should consider elongated life span with the passage of time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1836-1843
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• 2017

In this paper, we investigated fire cases those are believed to be caused by explosion of a electrolytic motor start capacitor. Using two types of commercially available electrolytic motor start capacitors, capacitor current and the possibility of capacitor explosion were tested. And the ignition possibility of the internal material leaked from a capacitor was also tested. In addition, experiments were conducted to see if the fire could spread when a capacitor was exposed to an external flame. From our test we observed that the current of the electrolytic motor start capacitor rose continuously to a certain level by product, if the capacitor was continuously energized with working voltage, and then the capacitor was exploded. The gas and liquid leaked from the capacitor by the explosion could ignite by an electric arc and an external flame. The capacitor current at explosion was different product by product, but each product had a certain current level at explosion. And the increase rate of the capacitor current until explosion was 24% and 31% for the products used in the experiment. We proposed the capacitor explosion prevention method that cuts off power when the capacitor current rises to a certain threshold level. The proposed method can be used if the current of the applied electrolytic motor start capacitor rises continuously and then the capacitor is exploded at a certain current level when the capacitor is energized continuously.

• Fire Science and Engineering
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• v.32 no.6
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• pp.91-99
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• 2018

Recently, the spread of ESS in Korea has increased and a fire accident has also occurred. By July 2018, there were a total of 7 cases. All 7 cases were ESS systems consisting of lithium-ion batteries and were burned down. Both the automatic fire extinguisher and the fire department were not able to digest. In this paper, the characteristics of ESS fire are analyzed based on recent ESS fire situation and field investigation, and the cause of fire is divided into environmental, electrical and thermal factors. As a result, it was found that the ESS fire was correlated with the installation environment of the system. In the domestic and overseas lithium ion battery test standard and ESS facility standard survey, the trends and differences of domestic and overseas facilities standards were identified. Based on the fire status and field investigationy, and domestic and overseas facility standard survey, measures were suggested to prevent and prevent the spread of fire in ESS fire.

• Journal of The Korean Association For Science Education
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• v.26 no.3
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• pp.406-414
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• 2006

This study investigated 7th grade students' context dependency on explanations about propagating path of light in three different contextual problems: observation of an object, observation of an object's image in a mirror, and observation of one's own face reflection in a mirror. Researchers examined student response in each context through interviews. The students were classified into four groups according to their explanations for the three different contexts. Each group was redivided into two or three subgroups in accordance with their conceptual features. After that, researchers investigated the characteristics of each subgroup. Main findings of the study indicated that (1) group 1 students' conceptions differed in each context; (2) group 2 students showed scientific conceptions in C1 context but in C2 context they showed visual ray conceptions or image misconceptions; (3) group 3 students did not show scientific conceptions in C3 context by strong misconceptions about one's own face reflection in the mirror. Also, this paper discussed the educational implications of the results.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.119-133
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• 2020

Recently, as famous YouTubers produce and broadcast videos that receive sponsorship and advertising such as indirect advertising (PPL), a so-called 'back advertising' controversy continues, and not only famous YouTubers but also entertainers are caught up in the issue. It is causing confusion among the public in Korea. This study attempts to find out the public's reaction before and after the controversy of 'back advertising' by YouTubers through comment analysis. Specifically, among text analysis using R programs, we intend to analyze the issue through various methods such as word cloud, qgraph analysis, LDA, and word2vec analysis, a deep learning technique. The target of the analysis was to analyze the channels of three YouTubers who belonged to the controversy of the 'back advertising' YouTuber and uploaded the 'Apology video'. The 5 most recent videos of Muk-bang YouTuber Moon Bok-hee, who has a similar content disposition to SussTV's Han Hye-yeon stylist, which was controversial, and Yang Pang, a YouTuber who showed various contents (August 09, 2020) Criterion and her first 5 videos uploaded were reviewed. As a result of the study, most of the comments that showed positive reactions before the controversy, but after the controversy, it was found that negative reactions accounted for most of the comments. Therefore, this study examines the degree of change of the public about influencers through comments after the controversy over 'back advertising' through various analysis using R program. This research also devises various measures to prevent the occurrence of back advertising of influencers in the future.