• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.156-164
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• 2004

This study was conducted to evaluate the effect of the application of green manure in the form of either green barley and Chinese milkvetch in reducing the amounts of N fertilizers and conventional fertilizers needed for paddy rice. Prior to rice transplanting, the green barley and Chinese milkvetch as a green manure produced respectively $668kg\;10a^{-1}$ and 3,492kg\;$10a^{-1}$ in fresh shoot weight basis. Calculated nitrogen content from harvested green manures was 3.9 and $17.8kg\;10a^{-1}$, respectively. Plant height and tiller number of rice increased when two kinds of green manure incorporated into soil. Above mentioned parameters also increased with increasing amounts of N fertilizers at both ear formation and heading stage of rice. Rice grain number was not affected by green manures treatment but increased when N fertilizers were applied. Although rice panicle and grain number increased with green manure treatments and fertilizer applications, whereas the percentage of ripened grain decreased. Chinese milkvetch with additional N fertilizer applications increased brown rice yield from 1 to 5% compared to rice yields in plots where non-green manure with the conventional amount of fertilizer application was applied. Rice treated with Chinese milkvetch and 30% of the conventional N fertilizer rate yielded the same as rice fertilized conventionally. During the rice growing season, $NH_4-N$ content of paddy soil was higher in green manures treatment than non-green manure one. Average $NH_4-N$ content in paddy soil drastically decreased after heading stage below $5.7mg\;kg^{-1}$ in non-green manure treated plots. While on the other, $NH_4-N$ content in soil slowly decreased in plots those were treated with green manures at harvesting stage, average $NH_4-N$ content was still greater than $5.5mg\;kg^{-1}$. Nitrogen content of rice shoot and brown rice seed was higher in green manure treatment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.392-395
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• 2009

응답면 기법을 활용하여 댐구조물과 같은 사회간접자본 시설물의 파괴확률을 구할 수 있다. 본 위험성 평가과정에서 응답면기법으로 구성한 한계상태 방정식을 유전자알고리즘의 적합도 방정식으로 사용하면, 핵심타입이나 지반종류, 지반다짐정도 등의 입력설계변수의 최적화 과정 속도를 더욱 신속화 시킬 수 있다. 제안된 응답면 기법과 유전자알고리즘의 복합해석기법은 신뢰성기반 최적화프로그램으로 기존의 유전자알고리즘의 수렴속도를 더욱 빠르게 하여주고, 특히 입력변수의 상하한계가 불확실한 경우에도 만족스러운 수렴성을 보장하여준다. 한계상태 방정식의 목표신뢰도 지수를 변화시켜면 해당하는 입력변수의 최적값을 출력하여주므로, 입력변수의 제약조건에 가격함수와 같은 가중치를 벌칙함수로 부여하면 가격최적화 프로그램으로 작용하게 되며, 시설물 운영자에게는 목표신뢰도에 대한 유지관리 기법과 정도를 의사결정 할 수 있도록 하여주는 기능을 가지게 된다. 조사된 많은 댐구조물의 파괴모드가 시간에 독립적으로 시공중 또는 시공완료 후 5년이내에 다수 발생하는바, 파괴모드를 조사하고 중요한 파괴모드인 파이핑 현상에 대해서 파괴확률을 계산하고 최적유지관리를 위한 개선된 유전자알고리즘 최적화 연산을 수행하였다. 기존 댐구조물과 같이 설계변수와 하중의 변동성을 알기가 어려운 경우에 유지관리비용 최소화를 위해서 본 제안 프로그램의 확장된 버젼은 중요한 기준을 제시하여줄 것으로 기대한다.

• Journal of the Korea Society for Simulation
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• v.16 no.4
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• pp.33-41
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• 2007

Service-Oriented Architecture(SOA) define the interaction method between two computing entities that one entity performs a unit task instead of another entity. This, unit task, is called "Service" and interaction of these services should have independency and loosely coupled task. The effect of SOA's main functions such as loosely coupled task and independent interoperability with influence the possibility of flexible message communication between different way and different users. In this article, we analyzed the performance about system stabilization between general web service and SOA based application that implemented through WCF based messaging framework using .NET Framework and integrated data presentation method. As the result of test, we confirmed that SOA environment using WCF have more advantages.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.91-102
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• 1991

Traditionally, a dynamic programming(DP) technique has been used to the multireservoir control system. The algorithm has inherent problem to increase computational requirements exponentially due to discretization of variables and expanding the dimension of the system. To solve this problem, this paper describes transforming the optimal control system into a quadratic programming(QP), using Laguerre polynomials(LP) and its properties. The objective function of the proposed QP is independent of time variable. The solution of the QP is obtained by nonlinear programming(NLP) using augmented Lagrangian multiplier method. The numerical experiment shows that the water level of reservoirs is higher than Lee's and the evaluated benefit value is about the same as other researcher's.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1628-1629
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• 2011

산업현장에서는 회전기기의 고체절연시스템(solid insulation system)의 열화정도를 평가하기 위하여 일정 진단주기에 맞춰 Off-line 상태에서 직류시험 및 교류시험을 통하여 효과적으로 절연물에 대한 상태평가를 시행하고 있다. 직류시험으로는 절연저항, 성극지수(PI) 시험 등이 있으며 교류시험으로는 교류전류시험(${\Delta}I$), 유전정접시험(${\Delta}tan{\delta}$), 부분방전(PD)시험이 있다. 여기서 부분방전은 절연체의 국부적인 열화현상을 추정할 수 있는 중요한 파라미터로, 부분방전시험(PD test)을 통하여 고정자권선(stator winding)에 대한 절연특성을 효과적으로 진단할 수 있다. 고압 전동기는 기동정지의 빈번함과 장기간 운전에 의해 열적, 전기적, 기계적 스트레스를 받게 되고, 이로 인해 과열, 진동, 절연파괴에 이르는 문제점이 발생되어 결국 시스템의 운전정지를 초래하는 심각한 사고로 이어질 수 있다. 따라서 고압 전동기의 절연상태를 주기적으로 감시하고 사고 징후를 검출하여 시스템을 안정적으로 운영하기 위한 고압 전동기 Off-line 절연진단에 대하여 기술하고 수차발전기에 대한 절연상태진단 결과를 바탕으로 절연시스템의 신뢰성 평가 방법에 대하여 고찰하고자 한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.164-171
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• 2006

In this paper, the fault tolerant system for BLDC motor has been proposed to maintain control performance under an open switch fault of inverter. The fault identification is proposed to two methods, which are using the difference between reference and actual current, and adding voltage sensors across lower legs of inverter. The reconfiguration scheme is achieved by the four-switch topology connecting a faulty leg to the middle point of DC-link using bidirectional switches. The proposed fault tolerant system quickly recovers control performance by short fault detecting time and reconfiguration of system topology. Therefore, continuous free operation of the BLDC motor drive system after faults is available. The superior performance of the proposed fault tolerant system is proved by simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.205-210
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• 2014

The micro grid considered in this paper consists of a diesel generator, a photovoltaic array, a wind turbine, a fuel cell, and a energy storage system. This paper explains and simulates the micro grid components in terms of accuracy and efficiency of having a system model based on the costs of fuel as well as operation and maintenance. For operational efficiency, the objective function in a diesel generator consists of the fuel cost function similar to the cost functions used for the conventional fossil-fuel generating plants. The wind turbine generator is modeled by the characteristics of variable output. The optimization is aimed at minimizing the cost function of the system while constraining it to meet the customer demand and safety of micro grid. The operating cost in fuel-cell system includes the fuel costs and the efficiency for fuel to generate electric power. To develop the overall system model gives a possibility to minimize of the total cost of micro grid. The application of optimal operation can save the interruption costs as well as the operating costs, and improve reliability index in micro grid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5752-5758
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• 2012

We investigate whether consumers' expectations affect managers' decisions. In particular, we examined whether the expectations that consumers make about the changes of their financial situations and family incomes are positively related to the decisions that managers make about advertising expenditures. We analyzed consumers' expectations as well as the advertising expenditures of 6,018 firms between 1991 and 2011. Our analysis supported our hypothesis. Our findings contribute to the discussions regarding the effect of consumer expectations on manager decisions as well as provide practical implications to advertising managers.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.307-312
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• 2008

최근 전기 전력 도메인의 IT화 (전력 IT) 가 본격적으로 진행되면서 전기 데이터를 취득하기 위한 기기들 뿐만 아니라 전력 운영 환경이 변화를 도모하고 있다 본 논문에서는 이런 전력 IT 의 일환으로 개발된 지능형 전력 정보 모니터링 시스템 (K-WAMS)을 소개하고자 한다. 이 시스템은 이기종 분산 환경에서 전력 정보를 실시간으로 전송 받아 현재 전력계통의 상황을 직관적으로 판단할 수 있는 정보를 제공하여 광역 정전을 예방하고자 하는 조기경보시스템 (Early Warning System) 이다. 또한, 전력계통의 안정성 여부를 판단하는 지능형 에이전트의 구현을 통해 광역 정전을 예견하는 지수를 제공하고, 실시간 데이터 처리 및 이력 데이터 저장 에이전트들을 통해 현재 취득되고 있는 현장 데이터 모니터링 기능을 제공한다. K-WAMS 는 실시간으로 전송 처리되는 고속 대용량 데이터들의 처리 지연, 동적 환경으로 인한 네트워크의 부하문제를 해결하기 위해서 IPC Shared Memory 기법을 이용하였고, 동적 프로세스들의 작업 스케줄링을 관리하기 위한 IPC Message Queue 기법을 이용하였다. 또한 논리적 기능 기반으로 설계된 현재 중앙 급전소(GCC) 단위의 설계 모델은 향후 지역 급전소(RCC) 단위로 설치 될 경우 재사용 되어 개발 생산성을 향상시킬 것으로 예상된다.

• The Journal of Korean Academic Society of Nursing Education
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• v.19 no.4
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• pp.542-548
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• 2013

Purpose: This study was conducted to explore clinical practice performance according to type of practice in students in pediatric nursing and the relationship with satisfaction of clinical practice. Methods: The subjects consisted of 531 nursing students (307 at a pediatric ward and 224 at a nursery) from 5 colleges of nursing. Data collected from March to June 2012 were analyzed using descriptive statistics, t-test, AVONA and Pearson correlation coefficients. Results: Clinical practice performance on direct nursing activity was significantly different according to the course on pediatric nursing, grade point average, and satisfaction of nursing major. Observation practice was different according to type of college, the course on pediatric nursing, grade point average, duration of practice and clinical educator in the pediatric ward. In the nursery, direct nursing activity was significantly different according to the type of college, the course on pediatric nursing, hospital type, and duration of practice. Observation practice was different according to type of college, satisfaction of a nursing major, and the clinical educator. In addition, significant correlations were found between clinical practice performance and satisfaction of clinical practice. Conclusion: Our research can assist effective pediatric nursing practice planning for nursing students.