• 디지털산업정보학회논문지
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• 제9권4호
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• pp.81-94
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• 2013

Recently, the dramatical increasement of personal information infringement makes the government strongly enforce the laws. The Key-point of law enforcement is the DB encryption. Nevertheless, DB encryption is the one of the hardest thing in the organization's security measures. The purpose of this paper is suggesting alternative means of residence numbers and showing the possibility of indicator usage for safety measures. This research suggested the best ways to make a decision through a before and after comparison of the DB encryption cost of the inherent identification number elimination in "Social Welfare consolidation service system". When this research result was applied in "Happiness-e-Um system", we found that the alternative means are more efficient than the residence number for encryption cost, system revision time and so on.

• 동력기계공학회지
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• 제12권2호
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• pp.12-17
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• 2008

Biodiesel fuel(BDF) which is easily produced from vegetable oils such as soybean oil and rice bran oil can be effectively used as an alternative fuel in diesel engine. But biodiesel fuel can affect the performance and emissions in diesel engine because it has different chemical and physical properties from diesel fuel. To investigate the combustion characteristics of biodiesel fuel as an alternative fuel for D.I. diesel engine, the experiments were carried out at the three-cylinder, four stroke D.I. diesel engine with T/C. Experimental parameters adopted a conventional diesel fuel and a blend of biodiesel fuel derived from soybean. As a result of experiments in a test engine, BSFC with blend of BDF resulted in higher than with diesel fuel. The ignition delay decreased with blend of BDF than with diesel fuel.

• 대한수학교육학회지:수학교육학연구
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• 제8권1호
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• pp.217-235
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• 1998

The purpose of this study is to define the altenative assessment and to suggest the method of scoring system. Alternative assessment includes any type of assessment in which student create reponses to a question rather than choosing a responses form given list( as for multiple choice, true/false, or matching). Alternative assessment can includes short answer questions, essay, performances, oral presentation, demonstrations, exhibitions, portfolios, and etc. To evaluate the each type of assessment, we can apply the method of holistic scoring and analytic scoring system. Also we have to concern the type of scoring mechanism directly relate to what we want to assess, our purpose for assessment fitting into the educational enterprise. Before applying the alternative assessment in our classroom, we need to step back and reconsider all our design features and teachers' responsibility.

• 동력기계공학회지
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• 제13권6호
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• pp.51-56
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• 2009

Recently, lots of researchers have been attracted to develop various alternative fuels in diesel engine. The use of biodiesel fuel(BDF) is an effective way of substituting diesel fuel in the long run. But biodiesel fuel can affect the performance and emissions in diesel engine because it has different chemical and physical properties from diesel fuel. In this study, to investigate the combustion characteristics of biodiesel fuel as an alternative fuel for D.I. diesel engine, experiments were carried out at the three-cylinder, four stroke D.I. diesel engine with T/C. As a result, shorter ignition delays were observed for the biodiesel blend cases relative to the diesel oil. The pick value of premixed combustion for the rate of heat release is increased with decreasing C.F.W. temperature.

• 한국물환경학회지
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• 제22권2호
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• pp.250-257
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• 2006

The objective of this study is to propose an alternative process for the small sewage treatment plants in rural communities. A biofilter has been used for biological wastewater treatment, which is becoming the alternative to the conventional activated sludge system. The proposed process used in this study, which is packed with floating media (i.e. expanded polystylene), has advantages of biofilter system and alternative flow system and they are incorporated into one process. Pilot and bench scale studies were performed using domestic wastewater. In the results of pilot plant study, it was observed that the stable effluent water quality was achieved and it met the present effluent criteria of suspended solid (SS), organic matters, T-N and T-P. In the study for determination of the cycle of backwashing, it was observed that the cycle of backwashing depended on BOD loading rates of influents. In the BOD loading rates of $0.5kg\;BOD/m^3{\cdot}day$ and $1.0kg\;BOD/m^3{\cdot}day$, the backwashing cycle of 28 hour and 16 hour were needed, respectively. The optimum backwashing time was 120~80 seconds at the media expansion rate of 50%. In the removal of SS, organic matters, T-N and T-P, SS removal was rather achieved by physical filtration than biological mechanism and the removal of organic matters except for SS, T-N and T-P were mainly rather achieved by biological mechanism than physical filtration. In bench-scale study, the effects of recirculation rate was investigated on removal of SS, TCOD, T-N and T-P. It was observed that the recirculation made removal efficiencies of SS, TCOD, T-N and T-P increased. Especially, in T-N removal, the increase of T-N removal efficiency of 40% was observed in the reicirculation rate of 1Q compared with 0Q.

• 한국산학기술학회논문지
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• 제13권4호
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• pp.1427-1433
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• 2012

본 연구에서는 이원냉동시스템에서 사용되던 저온용 규제프레온냉매 R13 및 고온용 규제프레온냉매 R503의 대체냉매로서 프레온혼합냉매 및 친환경적 자연냉매를 사용하는 이원냉동시스템의 성능특성을 규명하고자 하였다. 이를 위해 일반적인 이원냉동시스템의 운전범위에서 과냉각도, 과열도, 응축온도, 증발온도, 캐스케이드 열교환기에서의 온도변화를 고려하였다. 고온시스템 및 저온시스템의 작동유체의 종류에 상관없이 이원냉동시스템의 COP는 캐스케이드의 온도영향을 받고 있으며, 또한 과냉각도가 증가할수록 COP는 높아지지만, 과열도의 영향은 크게 받지 않았다. 따라서 본 연구에서 고온용 시스템 및 저온용 시스템의 작동유체로 대체 프레온혼합냉매 및 자연냉매의 냉매조합 중에서 (R23/R290), (R23/R600), (R23/R600a), (R23/R717), (R744/R404A) 냉매를 사용하는 이원냉동시스템의 COP는 저온측에 R23, 고온측에 R22를 사용하는 시스템에 비해 20 ~ 36% 높게 나타났다.

• Journal of Positioning, Navigation, and Timing
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• 제9권2호
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• pp.99-115
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• 2020

Since GNSS is easily affected by jamming and/or spoofing, alternative navigation systems can be operated as backup system to prepare for outage of GNSS. Alternative navigation systems are being researched over the world, and a multi-radio integrated navigation system using alternative navigation systems such as KNSS, eLoran, Loran-C, DME, VOR has been researched in Korea. Least Square or Kalman filter can be used to estimate navigation parameters in the navigation system. A large number of measurements of the Kalman filter may lead to heavy computational load. The decentralized Kalman filter and the federated Kalman filter were proposed to handle this problem. In this paper, the decentralized Kalman filter and the federated Kalman filter are designed for the multi-radio integrated navigation system and the performance evaluation result are presented. The decentralized Kalman filter and the federated Kalman filter consists of local filters and a master filter. The navigation parameter is estimated by local filters and master filter compensates navigation parameter from the local filters. Characteristics of three Kalman filters for a linear system and nonlinear system are investigated, and the performance evaluation results of the three Kalman filters for multi-radio integrated navigation system are compared.

• 한국정보통신학회논문지
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• 제17권1호
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• pp.233-241
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• 2013

무선 센서 네트워크에서 효율적인 대체 노드의 관리 및 유지 방법에 관한 문제는 매우 근본적인 문제 중 하나이다. 특히 계층적 클러스터에서 각 그룹 멤버 노드의 대체 기능이 가능한 노드(Alternative node)를 선정하여 임의 노드의 경로 단절시 대체 경로를 찾기 위해서는 대체 노드의 기능이 절차에 따라 실시간으로 경로를 복구 할 수 있어야 하며, 에너지를 최소화하여 네트워크를 유지 관리가 가능해야 한다. 본 논문에서 제안한 EEAP(Energy-Efficient Alternative Paths)는 이러한 양부 헤드 노드를 선정함에 있어서 에너지 잔량과 노드간의 거리등의 노드 속성 정보를 활용하여 각 경로에서 소모되는 비용과 노드의 관리에 있어 경비가 효율적인 경로의 대체 노드를 제공하게 됨으로 효율적인 에너지 관리를 할 수 있게 되어 전체 네트워크의 유지 시간을 향상 시킬 수 있는 결과를 보여주었다.

• 아동학회지
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• 제30권6호
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• pp.237-248
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• 2009

The reasons to attend Alternative Schools are : to compensate for the discontent over what is locally taught in state schools and to improve the students' satisfaction and social emotional development. In 2006, it was estimated that about a thousand Home Schools were set up. With the studies of Alternative Education and Home Schooling, the issues are : 1) the depth study of curriculum of Alternative Education with a wide range of subjects, 2) the institutionalization of Home Schooling, 3) educational methods for Home Schooling, 4) a research on Home Schooling's effectiveness. Their practical and political issues are : 1) to give the licence to the rest of schools and to formulate Education Law on Home Schooling, 2) to obtain government's financial support to the both sections, 3) to support a system of instructional contents and methods of Home Schooling, and 4) to select, share and popularize the best practices of Home Schooling.

• 한국정밀공학회지
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• 제14권1호
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• pp.168-173
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• 1997

A process planning system that generates alternative process plans offers multiple process plans for a part, thereby provides the flexibility to cope with the changes in shop floor status. In this paper, we intro- duce the concept of process net as a model for the generation of alternative process plans. We also show the usefulness of process net model in generating alternative process plans by implementing the developed sys- tem to construct process net, and devising an algorithm to generate alternative process plans for rotational parts.