• Defense and Technology
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• no.10 s.176
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• pp.66-71
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• 1993

지난 걸프전에서 이라크가 부설한 기뢰를 제거하기 위해 다국적군이 투자한 많은 시간과 노력, 장비와 인력은 유사시 기뢰전의 중요성을 새삼 일깨워주는 계기가 되었습니다 고가의 첨단장비에 의존하는 현대의 해상전에 기뢰부설은 비용 대 효과면에서 매우 효율적인 수단이 되고 있습니다 이에 우리도 기뢰전에 관심을 가져야 할 시점이라 생각되고, 기뢰전함정 세력의 확보와 함께 통합 전투체계 개념차원에서 도입해야 할 것입니다

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.44-52
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• 2003

항만 및 해안의 이용과 개발 그리고 연안해역공간에서 발생하는 각종 재해를 예방하는 측면에서 볼 때 해안에서 형성되는 여러 물리적인 현상들을 정확하게 이해하고 해석하여 필요에 따라 적절히 활용할 수 있는 것이 무엇보다도 중요한 과제이다. (중략)

• Informatization Policy
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• v.25 no.4
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• pp.65-83
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• 2018

This study examined the effects of smartphone usage types and excessive expectation for smartphone on adolescents' smartphone overdependence. It utilized the data of 3,454 adolescents (1,758 males and 1,696 females), aged between 13 and 19 from a smartphone overdependence survey of the National Information Society Agency. As a result of the hierarchical multiple regression analysis, age and household income had a negative effect on smartphone overdependence. Weekly smartphone usage time positively affected the serious consequences (sub-factor of smartphone overdependence). Among the different types of smartphone usage, information seeking, SNS, gaming, and the excessive expectation for smartphones had positive impact on smartphone overdependence. Smartphone usage for leisure seeking did not affect smartphone overdependence, but it negatively influenced serious consequences. Messenger use did not affect smartphone overdependence, but the use had a positive effect on salience, and a negative effect on serious consequences. The results of this study suggest that it is necessary to identify the types of smartphone use as well as the usage time to understand the smartphone dependence of adolescents. In addition, it seems necessary to recognize and correct the irrational excessive expectation for smartphone in order to prevent dependence and implement effective interventions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.3
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• pp.215-225
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• 2011

During the past decade, the performance-based design method of caisson breakwaters has been developed, which allows a certain damage while maintaining the function of the structure. However, the existing method does not consider the changing coastal environment due to climate change impacts so that the stability of the structure is not guaranteed over the lifetime of the structure. In this paper, a time-dependent performance-based design method is developed, which is able to estimate the expected sliding distance and the probability of failure of a caisson breakwater considering the influence of sea level rise and wave height increase due to climate change. Especially, time-dependent probability of failure is calculated by considering the sea level rise and wave height increase as a function of time. The developed method was applied to the East Breakwater of the Hitachinaka Port which is located on the east coast of Japan. It was shown that the influence of wave height increase is much greater than that of sea level rise, because the magnitude of sea level rise is negligibly small compared with the water depth at the breakwater site. Moreover, investigation was made for the change of caisson width due to climate change impacts, which is the main concern of harbor engineers. The longer the structure lifetime, the greater was the increase of caisson width. The required increase of caisson width of the Hitachinaka breakwater whose width is 22 m at present was about 0.5 m and 1.5 m respectively for parabolic and linear wave height increase due to climate change.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.280-281
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• 2008

전력시스템 전자기 과도현상은 시간 영역에서 정확하고 효과적으로 해석되어져야 한다. 그러나 대규모 전력시스템을 상세하게 표현하기 위해서는 엄청난 계산량이 필요하다. 따라서 전력시스템 과도현상을 해석하기 위하여 전력시스템의 작은 부분은 상세하게 표현하고, 나머지 부분은 효과적으로 등가 시스템이 필요하다. 본 논문에서는 모든 주파수 영역에서 등가 시스템을 개발하기 위하여 벡터 적합을 이용하여 S 영역 유리함수 계수를 추정하고, 과거항과 순간항을 고려한 주파수 의존 등가 시스템을 개발하였다. 개발한 FDNE의 우수성을 입증하기 위하여 테스트 시스템에 적용하여 시스템이 고장시 전자기 과도현상을 비교, 검토하였다.

• The Korean Journal of Rheology
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• v.6 no.1
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• pp.60-65
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• 1994

덕트유동에서 재료입자의 변형은 그 입자의 초기위치와 방향에 의존한다. 이러한 변 형과정을 이해하기 위하여 변형구배텐서를 덕트 전단면에 걸쳐 초기위치와 시간의 함수로 계산할수 있어야한다. 따라서 본 논문은 입자궤적 궤도에 접하는 직교좌표계를 선택하여 3 차원 덕트유동에서의 변형구배텐서를 덕트 전단면에 걸처 초기위치와 시간의 함수로 계산할 수 있어야한다. 따라서 본 논문은 입자궤적 궤도에 접하는 직교좌표계를 선택하여 3차원 덕 트 유동에서의 변형구배텐서를 효과적으로 계산할수 있는 간단한 방법을 제안한다. 이러한 특수 좌표계로부터 구해진 변형구배텐서가 덕트유동에서의 변형척도를 이해하는데에 매우 중요함을 알수 있었다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.733-735
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• 2001

본 논문에서는 Ad hoc 망에서 오류 발생률에 적응적인 LLC와 MAC 프로토콜은 설계하였다. 이 프로토콜은 무선 링크상에서 수신자의 피드백 정보에 의존한다. LLC 계층에서는 피드백 정보에 따라 적합한 FEC를 선택하여 부호화하고 MAC 계층에서는 이를 뒷받침하기 위해 오류 발생 패킷에 대한 새로운 재전송 메커니즘을 사용한다. 결과적으로 시간에 따라 변화하는 채널 환경에 적응하여 성공적으로 패킷을 전송함으로써 패킷 전달 지연시간을 단축시키고 제한된 채널의 대역폭을 효과적으로 사용한다.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.787-790
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• 2011

The objective of this study was to investigate the anticancer effects of Acer tegmentosum M. extracts. HepG2 hepatocarcinoma cells were treated with ethanol, chloroform, ethylacetate, butanol, aqueous fraction and hot water extract. The antiproliferative effect was evaluated by trypan blue exclusion, MTT-based viability assay and morphology. The trypan blue test showed that anticancer effect of the A. tegmentosum M. extracts on HepG2 cells increased gradually in proportion to the increasing concentration of the fractions. The butanol fraction showed the highest anticancer activity against HepG2 cells (p<0.05). The MTT assay indicated that the growth inhibition by the butanol fraction was dose-dependent. These results suggest that A. tegmentosum M. has the potential to inhibit the growth of hepatocarcinoma cells.

• Korean Journal of Psychosomatic Medicine
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• v.11 no.2
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• pp.196-204
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• 2003

Objectives: It is known that sedative hypnotics would make cross tolerance with alcohol and deteriorate quality of sleep in alcoholics. Light therapy is effective non-pharmacological intervention for sleep disturbance in circadian phase disorders, jet-lag, shift-work and age-related sleep disorders. Authors would investigate the effects of morning light therapy on sleep of patients with alcohol dependence during recovery state without withdrawal symptoms. Methods: 13 patients with alcohol dependence who have not any alcohol withdrawal symptom were recruited. Light therapy during 1 hour in the morning had been administered by 2500 Lux light box through serial 3 days. Sleep state of subjects were assessed by sleep log and the subjective satisfaction at sleep was by 100 mm visual analogue scale. Sleepiness, depressive mood, anxiety were evaluated by 100mm visual analogue scale at 8 AM, 2 PM and 8 PM. For assessment of performance ability that would be associated with sleepiness and vigilance, trail making test A, B and digit symbol substitution test were performed by two times on base line and 4th day. Univariate repeated-measures ANOVAs were performed for each measures except performance tests which were analysed by paired t-test. Results: Sleep latency and sleep efficiency were significantly improved with light therapy and satisfaction at sleep was. There was no significant difference in sleepiness at 2 PM with light therapy but sleepiness at 8 AM significantly decreased and at 8 PM increased. The time to complete Trail making test and digit symbol substitution test were significantly shortened at 4th day compared with baseline. Fatigue at 8 AM were not significantly changed with light therapy but at 2 PM and 8 PM significantly decreased. Depressive mood and anxiety were not significantly changed with light therapy. Conclusion: Although this study had some limitations, it showed that light therapy would be effective modality on sleep disturbance of patients with alcohol dependence who have recovered from alcohol withdrawal symptoms. It is proposed that short term light therapy could be used clinically for alcoholics with insomnia. In the future, long term controlled studies using more objective tools for sleep are required to further investigate the effect of light therapy in alcoholics.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.255-260
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• 2002

일반적으로 온실의 효과적인 온도관리를 위해서는 단열효과가 우수한 보온재를 이용하거나 또는 난방공간의 체적을 최소화 할 수 있는 터널재배가 바람직하다. 지금까지는 딸기, 수박 등 키가 작은 작물에 한하여 보온터널재배가 이루어지고 있는 실정이나, 보온터널의 개폐를 인력에 의존하고 있기 때문에 노동력이 많이 들고, 개폐에 소요되는 시간도 상당한 비중을 차지하고 있다. (중략)