• Title/Summary/Keyword: Control of demand and supply

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An Expanded Use of Reactor Power Cutback System to Avoid Reactor Trips in the Event of an Inward Control Element Assembly Deviation (제어봉 인입편차시의 원자로 비상정지 방지를 위한 출력 급감발 계통의 확대 적용)

  • Hwang, Hae-Ryong;Ahn, Dawk-Hwan
    • Nuclear Engineering and Technology
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    • v.25 no.2
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    • pp.276-284
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    • 1993
  • The ABB-CE System-80 reactor power cutback system(RPCS) is designed to enable continuous operation of the reactor without trip in the events of the loss of one of the two main feedwater pumps and loss of load, and thus improves plant availability in a cost effective manner. In this study expansion of RPCS has been investigated for continuous reactor operation without trip in the event of an inward control element assembly(CEA) deviation including a single rod drop. Under the expanded function of RPCS the control system will provide a rapid core power reduction on demand by releasing CEAs to drop into the core and reduce the turbine power, if necessary, to follow the reactor power variation. This design feature which is included as the new design features to be incorporated in the ABB-CE System-80+ meets the EPRI advanced light water reactor(ALWR) requirements. For this study core analysis models of System-80+ have been developed to simulate the nuclear steam supply system(NSSS) response as well as the RPCS initiation of rapid CEA insertion. The results of this study demonstrate that the reactor trip can be avoided in the event of inward CEA deviation including a single rod drop by the RPCS initiation and thus the plant availability and capacity factor would be increased.

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A study of SCM strategic plan: Focusing on the case of LG electronics (공급사슬 관리 구축전략에 관한 연구: LG전자 사례 중심으로)

  • Lee, Gi-Wan;Lee, Sang-Youn
    • Journal of Distribution Science
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    • v.9 no.3
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    • pp.83-94
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    • 2011
  • Most domestic companies, with the exclusion of major firms, are reluctant to implement a supply chain management (SCM) network into their operations. Most small- and medium-sized enterprises are not even aware of SCM. Due to the inherent total-systems efficiency of SCM, it coordinates domestic manufacturers, subcontractors, distributors, and physical distributors and cuts down on cost of inventory control, as well as demand management. Furthermore, a lack of SCM causes a decrease in competitiveness for domestic companies. The reason lies in the fundamentality of SCM, which is the characteristic of information sharing, process innovation throughout SCM, and the vast range of problems the SCM management tool is able to address. This study suggests the contemplation and reformation of the current SCM situation by analyzing the SCM strategic plan, discourses and logical discussions on the topic, and a successful case for adapting SCM; hence, the study plans to productively "process" SCM. First, it is necessary to contemplate the theoretical background of SCM before discussing how to successfully process SCM. I will describe the concept and background of SCM in Chapter 2, with a definition of SCM, types of SCM promotional activities, fields of SCM, necessity of applying SCM, and the effects of SCM. All of the defects in currently processing SCM will be introduced in Chapter 3. Discussion items include the following: the Bullwhip Effect; the breakdown in supply chain and sales networks due to e-business; the issue that even though the key to a successful SCM is cooperation between the production and distribution company, during the process of SCM, the companies, many times, put their profits first, resulting in a possible defect in demands estimation. Furthermore, the problems of processing SCM in a domestic distribution-production company concern Information Technology; for example, the new system introduced to the company is not compatible with the pre-existing document architecture. Second, for effective management, distribution and production companies should cooperate and enhance their partnership in the aspect of the corporation; however, in reality, this seldom occurs. Third, in the aspect of the work process, introducing SCM could provoke corporations during the integration of the distribution-production process. Fourth, to increase the achievement of the SCM strategy process, they need to set up a cross-functional team; however, many times, business partners lack the cooperation and business-information sharing tools necessary to effect the transition to SCM. Chapter 4 will address an SCM strategic plan and a case study of LG Electronics. The purpose of the strategic plan, strategic plans for types of business, adopting SCM in a distribution company, and the global supply chain process of LG Electronics will be introduced. The conclusion of the study is located in Chapter 5, which addresses the issue of the fierce competition that companies currently face in the global market environment and their increased investment in SCM, in order to better cope with short product life cycle and high customer expectations. The SCM management system has evolved through the adaptation of improved information, communication, and transportation technologies; now, it demands the utilization of various strategic resources. The introduction of SCM provides benefits to the management of a network of interconnected businesses by securing customer loyalty with cost and time savings, derived through the consolidation of many distribution systems; additionally, SCM helps enterprises form a wide range of marketing strategies. Thus, we could conclude that not only the distributors but all types of businesses should adopt the systems approach to supply chain strategies. SCM deals with the basic stream of distribution and increases the value of a company by replacing physical distribution with information. By the company obtaining and sharing ready information, it is able to create customer satisfaction at the end point of delivery to the consumer.

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Appraisal of Concrete Performance and Plan for Stable Use of EAF Oxidizing Slag as Fine Aggregate of Concrete (전기로 산화슬래그 잔골재를 사용한 콘크리트의 성능 평가)

  • Cho, Bong-Suk;Lee, Hoon-Ha;Yang, Seung-Kyu;Lee, Woong-Jong;Um, Tai-Sun
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.367-375
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    • 2009
  • Recently, more focus is shift to imbalances in aggregate market supply and demand and an exhaustion of natural resources. In this situation, Electric arc furnace oxidizing slag (EAF slag) has high application possibility as aggregate for concrete due to similar property with general aggregate. However, it is inherent the problem which causes pop-out by free-CaO contained in slag In this study, we've got the plan to assure the chemical stability of EAF slag, and then experimentally tested the mechanical performance and durability for the fine aggregate used EAF slag. On this test result, we suggest the application plan. At the result of this study, it shows that EAF slag would reduce the surface defect such as pop-out due to natural aging for the fixed hour and adjustment the grain size of EAF slag. And mechanical performance and durability according to the replacement rate of concrete service, were revealed more than equal or equal compare to general aggregate. Hereafter, quality control must precede not to impede the beauty of concrete surface as assure the safety for aging and processing. And, to establish the environmental resource recycling system for by-products of steel, it should be made development of various application and guideline of quality control for the EAF slag aggregate. Moreover, it must be constantly studied all kind of engineering performance and durability for related to this study.

Study on Stable Use of Stainless EAF Oxidizing Slag as Fine Aggregate of Concrete (스테인리스 전기로 산화슬래그의 콘크리트용 잔골재 활용방안 검토)

  • Cho, Bong-Suk
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.3
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    • pp.133-142
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    • 2014
  • Recently, more focus is shift to imbalances in aggregate market supply and demand and an exhaustion of natural resources. In this situation, Electric arc furnace oxidizing slag (EAF Slag) has high application possibility as aggregate for concrete due to similar property with general aggregate. In this study, We've got the plan to assure the chemical stability of EAF Slag, and then experimentally tested the mechanical performance and durability for the fine aggregate used EAF Slag. On this test result, we suggest the application plan. At the result of this study, it shows that EAF slag would reduce the surface defect such as pop-out due to natural aging for the fixed hour and adjustment the grain size of EAF Slag. And mechanical performance and durability according to the replacement rate of concrete service, were revealed more than equal or equal compare to general aggregate. Hereafter, quality control must precede not to impede the beauty of concrete surface as assure the safety for aging and processing. And, to establish the environmental resource recycling system for by-products of steel, it should be made development of various application and guideline of quality control for the EAF slag aggregate. Moreover, it must be constantly studied all kind of engineering performance and durability for related to this study.

Environment-friendly and Low-Carbon Agriculture for Demand-Supply Control and Food Security of Korean Rice (쌀 수급안정과 식량안보를 위한 친환경·저탄소 농업 전환방안)

  • Yang, Seung-Koo;Park, Pyung-Sik;Son, Jang-Hwan;An, Kyu-Nam
    • Korean Journal of Organic Agriculture
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    • v.26 no.1
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    • pp.99-128
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    • 2018
  • The cultivation area of rice as staple grains is decreasing in the domestic situation in Korea. Import volume of a duty in foreign rice is 409,000 tons for a year regardless increasing of production per unit area and decreasing of rice consumption. The total stock of rice is increasing cumulatively despite the effort for production mediation of rice. Therefore, maintenance of cultivation area and reduction of production are necessary for national foodstuffs security problems. Development of environment-friendly and low-carbon technology as alternative of global warming and aging of farm labor power is very important responsibility for descendants with creation of sustainable agriculture environment. As alternative for demand and supply stabilization of rice from all angles, first stage: extension of environment-friendly cultivation area as 17% Jeollanam-do level with maintenance of cultivation area under the present circumstances, second stage: extension of environment-friendly cultivation area as 25%, third stage: extension of environment-friendly cultivation area as 35%. From above mentioned scenario, reduction of rice production (60,000 tons), increases of production cost (59,200,000,000 Won), and reduction of income (201,500,000,000 Won) are estimated in first stage. Reduction of rice production (90,000 tons), increases of production cost (122,100,000,000 Won), and reduction of income (313,700,000,000 Won) are estimated in second stage. Reduction of rice production (380,000 tons), increases of production cost (222,000,000,000 Won), and reduction of income (464,500,000,000 Won) are estimated in third stage. From analysis results for partial tillage in transplanting cultivation complex (10ha), rice production is decreased 1.3~1.5 ton by complex. Production cost of rice is decreased and increases of income cultivation type. Gradual extension of environment-friendly agriculture and low-carbon partial tillage could be expected for environment maintenance of the territorial integrity, confidence of consumer, and high-efficiency of low-cost.

Characteristics of Lifelong Learning Policy and Developmental Tasks of South Korea (한국 평생교육 정책의 유형화와 발전과제)

  • Choi, Don Min;Kim, Hyunsoo
    • Korean Journal of Comparative Education
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    • v.28 no.5
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    • pp.47-69
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    • 2018
  • The purpose of this study is to classify the lifelong learning policy implementation process of lifelong learning in Korea according to the policy making decision models and to suggest developmental tasks. Korea's lifelong learning policy came to a full-fledged start with the enactment of the Lifelong Education Act in 2000. The Lifelong Education Act proposed the establishment of an open educational system as a strategy to realize the lifelong learning society. According to the Lifelong Education Act, the Korean government has developed several lifelong education policies such as providing learning opportunity for the underprivileged, facilitating lifelong learning city project, building lifelong learning culture, recognizing of experiential learning result, funding lifelong learning hub university, launching lifelong learning supporting administrative etc. The Korean lifelong system is characterized as Allison's (1971) governmental/bureaucratic, Ziegler and Johnson's (1972) legislative, Griffin's(1987) social control and Green's (2000) state-led models which make policy through the coordination between the government and the parliament and control bureaucratic power and educational qualifications. Lifelong learning policies should be managed in terms of supply and demand at the learning market. In addition, the state has to strengthen lifelong learning through supporting NGOs' activities and adult learners' tuition fee for the disadvantaged group of people.

Development of Human Resource Management Program for Protected Horticulture (시설재배 인력관리 프로그램 개발)

  • Myung, Dong-Ju;Shin, Gyung-Ho;Lee, Jeong-Hyun;Kim, Eun Ji;Lee, Beom-Seon
    • Journal of Bio-Environment Control
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    • v.30 no.4
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    • pp.359-366
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    • 2021
  • This study aimed to develop and verify the smart human resource management (HRM) program in a large scale greenhouse. HRM program delivers detailed work orders to workers and gathers work results by mobile phone application. Greenhouse managers can monitor the workload, work speed, quality of employee by HRM program and can analyse performance easily. Greenhouse Managers can set the work speed including 'twisting', 'trimming' and 'harvesting' in a greenhouse. It makes planning work schedule and assigns resources to each specific job easier. Therefore, the manager can arrange the number of employees to promote work performance and also easy to estimate the labor shortage. Greenhouse managers can evaluate the adequacy of the number of employees through job performance analysis by period and adjusts the supply/demand ratio of regular and non-regular employees. The HRM program can improve work efficiency by announcing the real-time work performance of all employees on a monitor screen to induce competition among workers and re-educate unripe employees who accomplish behind average to improving work skills.

A benchmarking of electricity industry for improving the integrated water resources management (IWRM) policy (통합물관리 정책실현을 위한 전력산업 벤치마킹 연구)

  • Kim, Dong Hyun;Kim, Taesoon;Jung, Heoncheol;Jeong, Eunsung;Lee, Seung Oh;Jung, Changsam
    • Journal of Korea Water Resources Association
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    • v.53 no.spc1
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    • pp.785-795
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    • 2020
  • Recently, the integrated management of the quantity and quality of water was been derived by the Ministry of Environment in Korea. This reconstruction in the national government organization can be recognized as the major politic measure. For this IWRM (Integrated Water Resources Management), it is necessary to be able to fairly distribute, operate and manage water resources in a situation where related techniques are needed to fully support, such as measuring exactly the demand and supply of water resources. The reason why IWRM is difficult, despite the development of related technologies, is because the management entities are highly diverse and their interests are much complicated. Thus, this study is tried to suggest specific improvement for current policies by benchmarking the KPX (Korea Power Exchange). In the field of water management as similar to the electric industry, there is an essential need for a working-level organization that can manage, control, monitor, and regulate water resources with practical and plenipotentiary control like the non-profit organization, KPX. Such time has come for decisive policy changes through benchmarking the structure, system, productivity, and challenges of the electricity industry in the water policy.

The Impact of the Mobile Application on Off-Line Market: Case in Call Taxi and Kakao Taxi (모바일 어플리케이션이 오프라인 시장에 미치는 영향: 콜택시와 카카오택시를 중심으로)

  • Kyeongjin Lee;Jaehong Park
    • Information Systems Review
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    • v.18 no.4
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    • pp.141-154
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    • 2016
  • Mobile application is growing explosively with the advent of a new technology: smartphones. Mobile application is a new marketing channel and performs as a start-up platform. This study examines the effect of mobile application on the off-line market. Despite the continuous declining demand for taxi service, paradoxically, the supply of taxi service has increased. The taxi industry can be categorized into general taxi and call taxi. General taxi is accidental and inefficient because it has to search for its own passenger. As call taxi takes the request of a passenger, it is more efficient than general taxi. However, the current defective passenger-taxi driver matching system and insufficient taxi driver management hinder the development of the call taxi market. Differences in differences (DID) is an econometrical methodology that examines whether or not an event has meaningful influence. This research uses DID to investigate the effect of the Kakao taxi application on the call taxi industry. Furthermore, it examines the effect of major companies' reckless diversification, which is considered unethical behavior. The passengers of call taxi data from August 2014 to July 2015 and those of designated driving service data of the same period were collected as the control group.

Evaluation of Algal Growth Limiting Factor in the Nakdong River by MBOD Method (MBOD법에 의한 낙동강의 조류증식 제한인자 추정)

  • Song, Kyo-Ook;Seo, In-Suk;Shin, Sung-Kyo;Lee, Suk-Mo;Park, Chung-Kil
    • Journal of Environmental Science International
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    • v.4 no.5
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    • pp.83-83
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    • 1995
  • The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 20$^{circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8∼96.0 mg$O_2$/l, 5.6∼94.0 mg$O_2$/l and 42.0∼220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.