• East Asian mathematical journal
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• 제34권3호
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• pp.317-330
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• 2018

We develop a mathematical model for the obesity dynamics to investigate the long term obesity trend with the consideration of psychological and social factors due to the increasing prevalence of obesity around the world. Many mathematical models for obesity dynamics adopted the modeling idea of infectious disease and treated overweight and obese people infectious and spreading obesity to normal weight. However, this modeling idea is not proper in obesity modeling because obesity is not an infectious disease. In fact, weight gain and loss are related to social interactions among different weight groups not only in the direction from overweight/obese to normal weight but also the other way around. Thus, we consider these aspects in our model and implement personal weight gain feature, a psychological factor such as body image dissatisfaction, and social interactions such as positive support on weight loss and negative criticism on weight status from various weight groups. We show that the equilibrium point with no normal weight population will be unstable and that an equilibrium point with positive normal weight population should have all other components positive. We conduct computer simulations on Korean demography data with our model and demonstrate the long term obesity trend of Korean male as an example of the use of our model.

• 한국분무공학회지
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• 제14권3호
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• pp.131-138
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• 2009

In the present study, spread-recoil behavior of a drop of shear-thinning liquid (xanthan solution) on a dry wall (polished stainless-steel plate) was examined and compared with that of Newtonian liquid (glycerin solution). Nine different kinds of xanthan and glycerin solutions were tested, including three pairs of xanthan and glycerin solutions, each having the same viscosity in low shear rate region ($10^{-2}-10^0\;l/s$). The drop behavior was visualized and recorded using a CCD camera. The maximum diameter and the spreading velocity of the xanthan drops turned out to be significantly larger and the time to reach their final shape was much shorter compared to the cases with the glycerin solutions, due to the smaller viscous dissipation resulted from lower viscosity in the higher shear rate region (>$10^0\;l/s$). As a result, the maximum diameters were measured to be larger than the predicted values based on the model proposed for Newtonian liquids, and the deviation was more pronounced with the solution with the larger viscosity variation. Consequently, viscosity variation with the shear rate was found to be a dominant factor governing the spread-recoil behavior of shear-thinning drops.

• 한국가금학회지
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• 제12권2호
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• pp.119-126
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• 1985

The purpose of the study is to review the evolutional process of the U.S. broiler industry into the integrated production and marketing systems and to examine the factors influenced such a structural change over the Past half a century. The study is also carried out under the consideration that the experience gained by the integrated U.S. broiler industry could be utilized in applying the system to any non-integrated broiler industries like one in Korea. The U.S. broiler industry has been prevailed in the typical independent operation of all stages, from factor supply through growing to dressing and marketing until such time as growers began to suffer from financial difficulties right after the end of the World Wat II due mainly to lowered price of broilers stemmed from whopping decrease of the demand, which eventually reflected to the allied agribusiness sectors. The feed business field was the first reactor to this situation so that a kind of measures was taken to cope with the problems faced in such a way to provide extended credit on feeds first and help obtain chicks or sell broilers later. This trend has been practiced for broiler related agribusiness through late 1940's to work together with growers by coordinating its function between two or more stages involved in broiler production and marketing process as a means of spreading risk and sharing profit between stages Participated. The integrated system and contract farming thus became Popular across the country through mid 1950's.

• 대한기계학회논문집A
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• 제38권1호
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• pp.59-63
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• 2014

타원형 기어는 오발 유량계에 사용되는 특수기어로써 타원형 모양에 의해 생긴 공간으로 물을 흘려보내 계측한다. 본 연구의 목적은 타원형 기어의 가공정도를 판단하고 불량을 가려내는 시스템을 머신비전을 이용하여 개발하는 것이다. 각종 산업분야에서 자동화가 확산되면서 머신미전의 수요는 늘고 있으며 업계전반의 생산공정 중 검사 공정에서 빼놓을 수 없는 인자가 되었다. 하지만 머신비전을 이용한 기어측정은 기어의 형상이 복잡하다는 이유로 잘 사용되지 않고 있다. 본 연구에서는 머신비전을 이용한 검사 프로그램으로 타원형 기어의 측정이 가능함을 보였으며 본 연구에서 설계한 타원형 기어의 가공정도를 판단할 수 있었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.914-922
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• 2019

Gas composition has a significant impact on the dispersion behavior and accumulation characteristics of blowout gas. However, few public studies has investigated the corresponding effect of gas composition. Therefore, this study firstly builds the FLACS-based numerical model about an offshore drilling platform. Then several scenarios by varying the composition of blowout gas are simulated while the scenario with the composition of "Deepwater Horizon" accident is regarded as the benchmark. Furthermore, the effects of the gas composition on the flammable cloud volume, the influenced area of flammable cloud, the influenced area of hydrogen sulfide and the critical time of the hydrogen sulfide spreading to the living area are analyzed. The results demonstrate that gas composition is a driving factor for dispersion characteristics of blowout gas. All the results can give support to reduce the risk of the similar accidents incurred by real blowouts.

• 경영과정보연구
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• 제10권
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• pp.33-66
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• 2002

Counterproductive work behaviors are behaviors by employees intended to harm their organization or organization members. Human is the being has a desire and behaviors. To understand behaviors of an individual, it is important to understand the personality which determines a difference between individuals. Narcissists has psychological traits to be likely to experience negative emotions, such as frustration, hostility or anger, and this psychological traits of narcissists are more likely to induce an aggression. In this view, the purpose of this study was to examine the relationships between counterproductive work behaviors and narcissistic personality characteristics and to explore psychological dynamics about how narcissistic personality characteristics had an effect on counterproductive work behaviors. As a result, facts known were as follows. First, narcissists has strong desires to maintain a sense of superiority over others and defend their egos against unpleasant evaluation information, even if the information is factual and accurate. Second, narcissists are hyper-sensitive to negative information and are more likely to encounter information or situations that challenge their positive self-appraisals by this view. Third, in response to these challenges, or ego threats, these individuals are more likely to experience negative emotions, such as anger, frustration, or hostility. Forth, this negative emotions lead to aggression and as a result, this is more likely to induce counterproductive work behaviors such as theft, sabotage, interpersonal aggression, work slowdowns, wasting time and materials, and spreading rumors. Thus, narcissism is another individual difference variable that may be an important factor in determining counterproductive work behaviors, particularly under conditions perceived to be difficult or stressful.

• 융합보안논문지
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• 제11권3호
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• pp.75-84
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• 2011

모바일 기술의 급격한 발전으로 스마트폰 사용이 확산되고 있다. 미래의 모바일 뱅킹 시장 활성화를 위해서 무엇보다 중요하고 우선시되는 것은 안전한 금융 거래이다. 그러나, 스마트폰 확산에 비례하여 검증되지 않은 많은 앱들이 개발되고 있는 상황에서 보안 위협은 높아질 수 밖에 없다. 현재 스마트폰 금융 거래 방식은 기존 공인인증서나 OTP기술을 그대로 모바일 환경에 적용하고 있으나, 많은 보안 문제점이 꾸준히 지적되고 있다. 본 논문은 다단계 인증 방법을 통해 보안성을 강화하고 물리적 부인방지 기능을 제공함으로써 기존의 인증 방식의 보안성을 개선하고자 한다.

• International journal of advanced smart convergence
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• 제7권1호
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• pp.1-6
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• 2018

In addition to the instability of energy import costs caused by the depletion of petroleum resources, which is a representative energy resource, and the strengthening of various regulations such as the convention on climate change, the plant for bio energy production, which is being watched as the next generation energy, and became subject of various complaints. In order to solve this problem, the bio-plant is underground and the ground is parked, making the convenience and accessibility of citizens more and more accessible. In this situation, the development of bioenergy production technology also increases the risk factor in bioenergy production process. Accordingly this paper explains method about apply the wide angle camera based AOA algorithm to the bio plant to prevent the accidents from spreading due to the lack of facilities and safety devices and the aging of the facilities and suggests a technique that can quickly identify the location and direction when it occurs.

• 물과 미래
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• 제27권3호
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• pp.123-134
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• 1994

돌출방류수로에 의하여 동일한 수심의 개수로에 방류되는 부력방류에 의한 연안귀환이 수리실험에 의하여 해석되었다. 부력방류는 온수를 방류하여 발생된다. 돌출방류로 인하여 부력류 하류에 형성되는 재순환영역의 크기는 비돌출방류에서 보다 증가하는 경향을 갖으나 황온도분포는 균일하고 횡단면 최대온도는 감소를 나타낸다. 높은 부력흐름율과는 반대로 낮은 부력흐름율 조건에서 단면평균온도 또는 열흐름율은 돌출길이의 영향이 무시할 정도이다. 비돌출의 경우에는 연안귀환에 유속비가 지배적인 매개변수이었으나 돌출방류의 경우에는 유속비와 후르드수가 다같이 지배적인 인자로 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2754-2767
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• 2019

Cloud computing is widely used in information spreading and processing, which has provided a easy and quick way for users to access data and retrieve service. Generally, in order to prevent the leakage of the information, the data in cloud is transferred in the encrypted form. As one of the traditional security technologies, access control is an important part for cloud security. However, the current access control schemes are not suitable for cloud, thus, it is a vital problem to design an access control scheme which should take account of complex factors to satisfy the various requirements for cipher text protection. We present a novel access control scheme based on proxy re-encryption(PRE) technology (PreBAC) for cipher text. It will suitable for the protection of data confidently and information privacy. At first, We will give the motivations and related works, and then specify system model for our scheme. Secondly, the algorithms are given and security of our scheme is proved. Finally, the comparisons between other schemes are made to show the advantages of PreBAC.