• Environmental and Resource Economics Review
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• v.23 no.1
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• pp.43-65
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• 2014

In this paper, we test for allocative efficiency of productive inputs including electricity and measure the divergence between the actual and optimal level of electricity for the chemical products, which is a relatively highly electricity-intensive sector in Korean manufacturing industries, by estimating a shadow cost function. Supposing cost minimization subject to market prices was achieved, we derive the price elasticities of demand for each input and simulate the impact of a 10% increase in power rate on its demand and supply price by estimating jointly a cost function with an inverse supply relation. The null hypothesis of allocative efficiency of inputs is rejected over the period 1982-2006. On average, electricity is used more than optimal level by 98% per year. The demand for electricity decreases by 11.4%, and supply price, on average, falls by 0.08%, other things being equal.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.371-374
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• 2004

The ultimate purpose of Supply Chain Management (SCM) is maximizing the profits of the overall Supply Chain (SC) through increasing customer satisfaction and decreasing operating cost. It can be successfully accomplished only when SC system balances demands with supply activities coordinated by aggregate planning, mid-term level of Supply Chain Planning(SCP). However, the existing measures to mainly estimate the specific function of SCM are not enough to evaluate the state of SC with respect to the balance between supply and demand in operating. To solve this problem, we develop a new SC performance measure, Balancing Point, using momentum concept. a fundamental knowledge of physics. Momentum concept can explain the relation among objects so that it can consider the balance between supply and demand in SC operating. The developed measure can not only consider the current state of the SC system but also take planned but not executed supply activities and upcoming demands into account. Therefore, using Balancing point, we can be aware of the unbalanced state of SC in advance.

• Journal of Korean Society for Quality Management
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• v.21 no.1
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• pp.11-21
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• 1993

In this paper, we survey the current status of measurement labor in Korean Industry. At the same time we try to predit the demand and supply of measurement labor to suggest policy measures for equilibrium in measurement labor market. We use a general production function for the prediction which include a set of general homethetic production function.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.679-687
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• 2013

Although stable and safe drinking water supply to the customers is a basic function of multi-regional water supply systems in Korea, most systems have their vulnerabilities in emergency time due to the branch-type. Application of connections from the other water supply system can provide a solutions for these tentative problems. This paper describes reduction planning of water supply accidents that can minimize a service interruption to customers in multi-regional water supply system by connecting pipe lines between local water supply systems in Mokpo city areas. The result of this study shows that Juam dam multi-regional water supply systems can cover all of the water shortage in southern parts of Jeonnam multi-regional water supply systems by transmitting water through connected pipes between local networks. This can be effective to supply water interactively in various contingencies, when a pipe line accident occurs in southern area of Jeonnam multi-regional water supply systems. On the contrary, southern area of Jeonnam multi-regional water supply systems can cover 99.5 %($62,500m^3/day$) of the water shortage of Juam dam multi-regional water supply systems when service interruptions caused by various pipe accidents occur in the system.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.302-311
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• 2016

This paper proposes a hybrid ESS that integrates an energy storage system (ESS) with an uninterruptible power supply (UPS). The hybrid ESS has a demand management and emergency power supply function while increasing the battery utilization of the UPS, which has just been used in a power failure. In addition to the critical load, the proposed system augments the capacity of emergency generation using an additional load, which has voltage and frequency-dependent characteristics to the grid side. The control algorithm of the AC-DC converter and bidirectional DC-DC converter is proposed for demand management and emergency power supply. Furthermore, seamless and autonomous transfer methods to alleviate the transient during mode transfer are proposed. To validate the proposed control scheme, experimental results from a 5 kW prototype are provided.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.545-546
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• 2006

A problem of oil supply for a reciprocating compressor is very significant for an evaluation of reliability. Since a rotational motion of a crank shaft for the reciprocating compressor with small capacity is used for a power source of oil supply, a centrifugal force of the rotational shaft provides a stroke of oil inside the shaft like a centrifugal pump. The pumped oil rises following an inner wall and provided to a bearing passed through an oil supply hole at the side of the shaft for lubrication of the bearing. In this study, the amount of oil supply has been investigated by a numerical analysis for various conditions such as a shape of a groove, rpm of the compressor, and a shape of a flow channel. Also, a method of increasing oil supply for a low rpm has been studied so that the function can be improved for a variable condition.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.2
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• pp.75-87
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• 2019

This paper presents a fully digital controlled power supply unit for the wireless controlled dimmable LED lighting system. The proposed power supply designed using a fly-back converter, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve a high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. For a wireless remote control function, the Zigbee modem is equipped in the proposed power supply. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the usefulness of the proposed power supply is verified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6959-6968
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• 2015

This study aims to update the supply-demand model of wood products(FOSMO-2013) and to forecast mid and long run supply and demand for each products. The subjects of the study include sawnwood, plywood, particle board, fiberboard(MDF), and pulp. The updated partial equilibrium model is composed of supply function, import demand function, demand function, price relation function. The long run outlooks of world prices of wood and wood products are imported from the results of Buongiorno(2012). This study also adopt Buongiorno's scenarios, which includes three scenarios of IPCC(A1B, A2, B2) and the other one with assumption of increasing fuelwood consumption of A1B scenario. The result says that the domestic productions of wood products are expecting to decrease while the imports of them increase even there are some differences among the products as well as scenarios.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.739-745
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• 2001

The objective of this research is to analyze the ventilation effectiveness in the non-isothermal air supply using mixing and displacement ventilation systems for indoor air quality control and management. In this study, a ventilation effectiveness is evaluated in a simplified model chamber using a tracer gas technique of $CO^2$ gas injected into a supply duct as a function of ventilation rates, supply/extract sites and cooling/heating air supply. The ventilation effectiveness decreased with increasing ventilation rate on the cooling and heating conditions. And the ventilation effectiveness of case 3 (down supply and upper extract) was better thant that of case 1(upper supply and upper extract) and case 2(upper supply and down extract) with the cooling supply conditions. but for the heating supply air conditions, the ventilation effectiveness of case 2 was better than that of case 3 and case 1.

• The Pure and Applied Mathematics
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• v.21 no.2
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• pp.141-145
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• 2014

In the paper, by directly verifying an inequality which gives a lower bound for the first order modified Bessel function of the first kind, the authors supply a new proof for the complete monotonicity of a difference between the exponential function $e^{1/t}$ and the trigamma function ${\psi}^{\prime}(t)$ on (0, ${\infty}$).