• 환경생물
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• 제32권4호
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• pp.311-318
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• 2014

PFOS (Perfluorooctane sulfonate) 노출에 따른 Macrophthalmus japonicus의 생태독성학적 판정점을 탐색하고자 생존율, 부속지 탈락 수, 갑각 및 내장 색의 변화를 관찰하였다. 그 결과, PFOS 노출에 따른 생존율의 감소는 농도 의존적 패턴을 보여 상대적 고농도인 PFOS $30{\mu}gL^{-1}$에서 168시간 노출시 24%의 가장 낮은 생존율을 나타내었다. 부속지 탈락은 대조군에 비해 PFOS 노출군에서 탈락빈도가 증가하였다. 또한 대조군에서는 갑각색의 변화가 관찰되지 않았으나, PFOS 노출군에서는 백화현상이 농도의존적 패턴으로 관찰되었다. 내부 장기의 색 선명도도 PFOS 노출군에서 대조군에 비해 변화가 나타났다. 이러한 결과는 해양 저서환경의 모니터링을 위한 생물적 주요한 정보를 제공해 줄 것이다.

• Child Health Nursing Research
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• 제7권1호
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• pp.62-73
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• 2001

The purpose of the study is to identify the differences about knowledge and attitude between the subjects exposed to pc pornography and the control group not exposed to pc pornography. The study was executed from July 12 through July 16. The subjects were 423 middle school boys. The comparison points were their ethical sexual knowledges and sexual attitudes. The collected data was analysed by SPSS WIN(including multiplicand, percentage, χ²-test, revised Fisher and t-test). The results of their study were as follows ; 1. The pc-related characteristics of the subjects. The subjects exposed pc pornography showed 51.8％ rate of exposure to printed pornography. The control group showed the rate of 26.4％. The former group owned their pc(81.5％), however, the latter group showed 66.7％. The former group set their pc sets in their study rooms(66.1％) however, the latter group installed those in their study rooms(73.6％). The former group experienced internet pc communications(62.5％),however, the latter group showed 40.2％. The former group made use of their pc sets in recreation(entertainment) programs(77.0％), however, the latter group showed the rate of 67.8％. The former group showed that their school performance levelled up after their pc manipulation(80.0％), however, the latter group showed the rate of 86.2％. The former group replied that their pc manipulation contributed to their friendship(50.3％), however, the latter group showed the higher rate of 74.7％. The both groups replied that their family dialogs and contacts rather reduced (78.9％ and 78.2％ respectively). The both groups revealed that they reduced the TV watching the rate 76.5％ and 48.3％ respectively. The differences between two groups were surveyed in the level of 95％ significance and the items such as 'contacts to printed pornography, pc possession or none, pc use rate, friendship occasions and the reduced time of TV watching' showed the significant differences. 2. The differences of two groups' sexual knowledges. As to the sexual knowledges, the both groups showed 41.1 and 34.1 points against 100 points respectively. The statistical differences were significant(t=2.72, p=.007). The 5 items among 17 showed the significant differences between two groups. 'The concept of masturbation' was χ²=5.033, p=.025. 'The prejudice to masturbation' showed χ²=9.902, p=.002 'The difference between female and male as to sexual excitement' showed χ²=7.985, p=.005. 'The positiveness of masturbation' showed χ²=10.205, p=.001. 'The differences between two sexes as to sexual impulse and sexual desire' showed χ²=8.463, p=.004. In conclusion, The former group showed the higher knowledges than the latter group. 3. The differences of two groups' sexual attitudes. The 4 items such as 'the curiosity to the other sex'(t=2.22, p=.027), 'the attention to pornography'(t=3.39, p=.001), 'the permission to pre-marriage intercourse'(t=2.15, p=.032) and 'the preference to the female body exposure'(t=2.67, p=.008) showed the differences between two groups as to sexual attitudes.

• 한국산업융합학회 논문집
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• 제23권5호
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• pp.809-815
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• 2020

A number of investigations and studies have been conducted in various fields regarding the sediment disasters of Mt. Woomyeon that occurred in July 2011. We collected and compared the topographic information of the general points where debris flows did not occur and the collapse points where the debris flow occurred in order to find out the characteristics of the collapse points in Woomyeon mountain. The collected topographic information is altitude, curvature, slope, aspect and TPI(topographic position index). As a result of comparison, there were relatively many collapse points at an altitude of 210m to 250m, and at a slope of 30° to 40°. In addition, the risk of collapse was low in a cell where the curvature was close to 0, and the risk was higher in concave terrain than in convex terrain. In the case of TPI, there was no statistical difference between the general points and the collapse points when the analysis radius was larger than 200m, and there was a correlation with the curvature when the analysis radius was smaller than 50m. In the case of debris flows that are affected by artificial structures or facilities, there is a possibility of disturbing the topographic analysis results. Therefore, if a research on debris flow is conducted on a mountain area that is heavily exposed to human activities, such as Woomyeon mountain, diversified factors must be considered to account for this impact.

• 소성∙가공
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• 제17권7호
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• pp.528-533
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• 2008

Cavity in the mold is exposed to high pressure during injection molding operation. Injection molded articles with deep depth are often demanded as design variety increases. Subsequently mold becomes weak and deformation increases as the mold depth increases. Thus the injection molds for deep depth articles should be designed to hold out high pressure or stress concentration and large deformation. Through this study, equation for mold design was examined and suggested novel method to determine equation for mold design with deep depth. Novel equation developed in this study was modified from beam theory considering cantilever and two points bending situation while previous equation was modified from just cantilever bending situation. The validity of novel equation was verified through computer simulations for various mold side and wall thickness.

• Toxicological Research
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• 제34권4호
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• pp.311-324
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• 2018

Arsenic is one of the most toxic environmental toxicants. More than 150 million people worldwide are exposed to arsenic through ground water contamination. It is an exclusive human carcinogen. Although the hallmarks of arsenic toxicity are skin lesions and skin cancers, arsenic can also induce cancers in the lung, liver, kidney, urinary bladder, and other internal organs. Arsenic is a non-mutagenic compound but can induce significant cytogenetic damage as measured by chromosomal aberrations, sister chromatid exchanges, and micronuclei formation in human systems. These genotoxic end points are extensively used to predict genotoxic potentials of different environmental chemicals, drugs, pesticides, and insecticides. These cytogenetic end points are also used for evaluating cancer risk. Here, by critically reviewing and analyzing the existing literature, we conclude that inorganic arsenic is a genotoxic carcinogen.

• 한국멀티미디어학회논문지
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• 제20권3호
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• pp.456-464
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• 2017

The epigraphy is a text on metal or a text on stone. The value of epigraphy can be used to identify historical facts of the past. It is a good record to understand the past life and culture. But it is difficult to decode the character of the epigraphy which has been exposed to the outdoor for a long time. In this study, the proposed techniques are consisted of 3 parts: (1)The surface division into information area, non- information area, and undifferentiated area. And then, (2) The selection of points in the non-information area and finding a reference plane with the minimum error. (3) Flattening the points perpendicular to the reference plane and decoding characters on information area. This research contributes to narrow the scope of a particular letter and to read the controversial letters on the Pohang Jungsoengri Silla Stone Monument(Korea's national treasure number 318).

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.149-153
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• 2008

The cavity of mold is exposed to high pressure during injection molding operation. Injection molded articles with deep depth are often demanded as design variety increases. Mold becomes weak and deformation increases as the mold depth increases. Thus the injection molds for deep depth articles should be designed to hold out high pressure or stress and large deformation. Through this study, equation for mold design was examined and suggested novel method to determine equation for mold design with deep depth. Novel equation developed in this study was consisted with cantilever and two points bending while previous equation was modified from just cantilever bending. The validity of novel equation was verified through computer simulation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.301-304
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• 2008

The cavity of mold is exposed to high pressure during injection molding operation. Injection molded articles with deep depth are often demanded as design variety increases. Mold becomes weak and deformation increases as the mold depth increases. Thus the injection molds for deep depth articles should be designed to hold out high pressure or stress and large deformation. Through this study, equation for mold design was examined and suggested novel method to determine equation for mold design with deep depth. Novel equation developed in this study was consisted with cantilever and two points bending while previous equation was modified from just cantilever bending. The validity of novel equation was verified through computer simulation.

• Bulletin of the Korean Chemical Society
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• 제16권3호
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• pp.269-277
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• 1995

A topological theory has been introduced to extend the theory of Balsara and Nauman to evaluate the entropy of in homogeneous polymer solutions. Previous theories have considered only the terms about the displacement of junction points, while the present theory has obtained a more complete expression for the entropy by adding the topological interaction terms between strands. There have been predicted the characteristics of the spinodal decomposition and the interfacial tension of polymer solutions from the resultant expression. It is exposed that the theoretically predictive values show good agreement with the experimental data for polymer solutions.

• Asian Pacific Journal of Cancer Prevention
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• 제13권6호
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• pp.2961-2966
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• 2012

Extremely low frequency electro magnetic fields (EMFs) have been classified as possibly carcinogenic to humans by the International Agency for Research on Cancer. An increased number of chromosomal alterations in peripheral lymphocytes are correlated with elevated incidence of cancer. The aim of the present study was to assess occupationally induced chromosomal damage in EMF workers exposed to low levels of radiation. We used conventional metaphase chromosome aberration (CA) analysis and the micronucleus (MN) assay as biological indicators of non ionizing radiation exposure. In the present study totally 70 subjects were selected including 50 exposed and 20 controls. Informed written consent was obtained from all participants and the study was performed in accordance with the Declaration of Helsinki and the approval of the local ethical committee. A higher degree of CA and MN was observed in exposed subjects compared to controls, the frequency of CA being significantly enhanced with long years of exposure (P<0.05). Moreover increase in CA and MN with age was noted in both exposed subjects and controls, but was significantly greater in the former. The results of this study demonstrated that a significant induction of cytogenetic damage in peripheral lymphocytes of workers occupationally exposed to EMFs in electric transformer and distribution stations. In conclusion, our findings suggest that EMFs possess genotoxic capability, as measured by CA and MN assays; CA analysis appeared more sensitive than other cytogenetic end-points. It can be concluded that chronic occupational exposure to EMFs may lead to an increased risk of genetic damage among electrical workers.