• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.546-555
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• 2019

The purpose of this study was to improve the performance of the bogie-type crematory, which is the mainstream of domestic crematory equipment. A field scale technology was investigated via increasing the volume by changing the shape of the furnace and reducing the cremation time and saving the energy usage through the optimization of burner combustion control. First, the optimized structural design through thermal flow analysis increases the volume of the main combustion chamber by about 70%, which increases the residence time of the combustion flue gas. A designed pilot crematory was then installed and the combustion behavior was tested under various operating conditions and the optimum operating plan was derived from for each furnace shape. Based on the results, the practically applicable crematory was designed and installed at Y crematorium in the P City. Optimal combustion conditions could be derived through operating the demonstration crematory furnace. The crematory time and fuel consumption could be minimized by increasing the energy efficiency by increasing the residence time of high temperature combustion flue gas. In other words, the crematory time and fuel consumption were 38 min and $21.8Nm^3$, respectively which were shortened by 44.1 and 54.4% lower than that of the existing crematory, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.476-482
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• 2019

Regulatory protocols such as the Convention on Climate Change and the regulation of greenhouse gas emissions act as catalysts for the development of high-efficiency energy equipment and the efficient use of energy. Among the fields where energy consumption is high, the electric heating equipment is not efficient. The electric boiler mainly uses a method of circulating water by contacting the heater. When the existing electric boiler is used, the water minerals are contacted with the high-temperature heater to be carbonized and adsorbed, thereby promoting the corrosion of the heater and lowering the efficiency of the heater. For this reason, an electric induction boiler, which has high energy efficiency and is applied to an induction heating system that can uniformly heat the object to be heated rather than conduction or convection heating, is in the limelight. This method induces a boiler pipe And it is recognized as an alternative that can solve the problem that occurs when heating is performed by direct heating. Despite the fact that research on induction heating has been conducted for a relatively long period of time, there have been few studies on the electrothermal technology using induction heating. Therefore, in this paper, to improve the heat efficiency of electric induction boiler, the influence of the cross sectional area, number of windings and winding layers is analyzed by finite element method through parametric study method. The method of finding the design point which maximizes the total loss is proposed by the alternating winding design method which can maximize the heat generation by analyzing copper and iron losses.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.196-205
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• 2021

As industrial safety increases, various industrial accident prevention technologies using smart factory technology are being studied. However, small and medium enterprises (SMEs), which account for the majority of industrial accidents, are having difficulties in preventing industrial accidents by applying these smart factory technologies due to practical problems. In this study, customized monitoring and warning systems for each type of industrial accident were developed and applied to the actual field. Through this, we demonstrated industrial accident prevention technology through appropriate smart factory technology used by SMEs. A customized monitoring system using vision, current, temperature, and gas sensors was established for the four major disaster types: worker body access, short circuit and overcurrent, fire and burns due to high temperature, and emission of hazardous gas. In addition, a notification method suitable for each work environment was applied so that the monitored risk factors could be recognized quickly, and real-time data transmission and display enabled workers and managers to understand the disaster risk effectively. Through the application and demonstration of these appropriate smart factory technologies, the spread of these industrial safety technologies is to be discussed.

• Journal of Korea Foundry Society
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• v.44 no.1
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• pp.3-8
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• 2024

Reducing industrial waste and improving the atmospheric environment recently have emerged as important tasks for the casting industry. Various types of artificial sand that can replace natural sand have been developed and used to solve problems that arise with the use of conventional foundry sand and to improve the foundry environment. However, only limited physical properties provided by overseas suppliers are known and in-depth comparative analyses with existing natural sand are lacking. For the design of the casting process, a wide range of thermal properties must be secured not only at room temperature but also at high temperatures. In addition, it is important to compare and analyze the differences in thermal properties between existing natural and artificial sand because changes in thermal properties require changes in the design of the casting method. In this study, the thermal behavior of the mold was analyzed through a thermal expansion test of mold blocks for natural and artificial sand., To this end, a thermal property test to evaluate thermal conductivity was performed by determining a temperature range. The results of the experiment, revealed that the thermal conductivity was 5-40% higher in artificial sand than in natural sand, and the coefficient of thermal expansion was about 15% lower for artificial sand. However, there was not a significant difference in specific heat regardless of the composition.

• Journal of Korean Society of Steel Construction
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• v.20 no.5
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• pp.655-663
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• 2008

In this research, the fire resistance of Concrete-Filled Circular Steel Tube Columns (CFT) was evaluated by numerical analysis. As the materials of CFT columns, the steel of SPSR 400 grade and the concrete of 27.5MPa, 37.8MPa strengths were used. Significant parameters,such as concrete strength, axial load, and cross-sectional dimensions were determined. To verify the accuracy of the numerical analysis,the analysis results were compared with the former experiment results. The effect of the fire resistance time, axial load ratio, cross-sectional dimensions and concrete strength was evaluated by comparison with the fire resistance of the square CFT columns. This research showed that the structural behavior and fire resistance from the findings of numerical parametric studies showed a similarity to that of the experimental results. Therefore, this numerical analysis is reasonable in estimating the fire resistance of the circular CFT column.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.943-945
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• 2002

This paper presents conceptual design and 3-D electromagnetic analysis of 1MVA transformer with BSCCO-2223 High Tc Superconducting (HTS) tapes. The rated voltages of each sides of the transformer are 22.9 kV and 6.6 kV, and double pancake windings were adopted. High voltage and Low voltage sides were composed of several double pancake windings. Four HTS tapes were wound in parallel for the windings of low voltage side and were transposed in order to distribute the currents equally in each conductor. The transformer core was designed as a shell type core made of laminated silicon steel plates and the core is separated with the windings by a cryostat with Fiberglass Reinforced Plastics(FRP). A sub-cooling system using $LN_2$ were designed to maintain the coolant temperature of 65K. Finally perpendicular components of magnetic field applied to tapes were calculated 0.24T in the rated operation using 3-D analysis. A real 1MVA HTS transformer will be manufactured in near future based on the design parameters presented in this paper.

• Journal of the Korean Institute of Gas
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• v.14 no.1
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• pp.1-7
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• 2010

In this paper, cycle performance analysis of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The main results were summarized as follows : The COP of two-stage cascade refrigeration system increases with the increasing subcooling degree, but decreases with the increasing superheating degree. The COP of two-stage cascade refrigeration system decreases with the increasing condensing temperature, but increases with the increasing evaporating temperature. And the COP of two-stage cascade refrigeration system increases with increasing the compressor efficiency. Therefore, superheating and subcoolng degree, compressor efficiency, and evaporating and condensing temperature of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system have an effect on the COP of this system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.3
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• pp.267-273
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• 2013

In order to provide effective operating conditions for the fan in a wet cooling tower with film fill, a new program to search for the minimum fan power was developed using a model of the optimal total annual cost of the tower based on Merkel's model. In addition, a type of design map for a cooling tower was also developed. The inlet water temperature and heat load were considered as key parameters. The present program was first validated using several typical examples. The results showed that for a given heat load, a three-dimensional graph of the fan power (z-axis), mass flux of air (x-axis, minimum fan power), and inlet water temperature (y-axis, maximum of minimum fan power) showed a saddle configuration. The minimum fan power increased as the heat load increased. The conventionally known fact that the most effective cooling tower operation coincides with a high inlet water temperature and low air flow rate can be replaced by the statement that there exists an optimum mass flux of air corresponding to a minimum fan power for a given inlet water temperature, regardless of the heat load.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1007-1013
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• 2013

This study aims to analyze the aerodynamics when the geometry of the turbine rotor is modified. The turbine used in this study is a small engine used in the APU of a helicopter. It is difficult to improve the performance of small engines owing to the structural weakness of the blade tip. Therefore, the improvement of the hub geometry is investigated in many ways. The working fluid of a turbine is a high-temperature and high-pressure gas. The heat transfer rate of the turbine surface should be considered to avoid the destruction of blade owing to the heat load. The SST turbulence model gives an excellent prediction of the aerodynamic behavior and heat transfer characteristics when the numerical simulations are compared with the experimental results. In conclusion, the aerodynamic efficiency is improved when a bulbous design is applied to the leading edge near the hub. The endwall loss is reduced by 15%.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.121-121
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• 2012

산업이 고도화, 다원화, 세계화되고 있는 현대사회는 다기능성, 고물성, 극한 내구성을 가지며 환경 친화적이면서 에너지 효율을 극대화시킬 수 있는 다기능 소재의 개발을 요구하고 있다. 이러한 시점에서 다양한 물성을 동시에 발현이 가능한 코팅 소재는 향후 미래에 중요한 원천 소재로서 주목되고 있다. 특히, 환경에 의해 쉽게 물성 및 구조의 변화가 쉬운 종래의 코팅소재와는 달리, 다양한 외부환경에서도 미세 구조 및 물성을 안정적으로 유지할 수 있는 신개념의 코팅 소재의 개발이 절실히 요구되고 있다. 이를 위해서는 코팅소재의 다 성분화가 필수적이다. 최근의 코팅 기술은 2가지 이상의 물성, 특히 서로 상반되는 물성을 동시에 구현할 수 있는 소재의 개발을 요구하고 있다. 이러한 물성의 구현을 위하여 더 많은 성분으로 구성되며 더욱 복잡한 조직으로 구성된 코팅층에 대한 개발이 진행이 필요하다. 본 연구에서 목표로 하는 신 개념의 원천소재기술은 4성분계 이상의 원료 물질을 단일 타겟으로 제조하여, 단순한 공정으로서 단일 코팅층 내에 다양한 성분과 10 nm 미만 크기의 나노 결정립/나노 비정질로 구성된 나노 복합 구조의 형성이 가능하도록 하는 기술을 개발하고자 한다. 이를 통해 복합기능 3 이상의 다기능성 부여는 물론, 그림 1에 정리된 기존 코팅재에서 결여된 특성을 포함한 극한 기능성(광대역 윤활성, 전자 이동 제어에 의한 온도 저항 계수 및 전기 저항 조절, 고온 열적 안정성, 내산화성, 고열전도율, 초저마찰/내구성/초고경도성 등)의 구현이 가능한 복잡한 형태의 나노 복합 코팅층 소재 개발이 가능하도록 하는 기술이다. 또한 기존 코팅재의 구조적 결함을 통해 발생하는 내식성 문제를 방지할 수 있는 기술이다. 다성분계 모물질의 개발이 중요한 이유는 다수의 성분 원소를 합금 상태로 형성시킴으로서, 단일 소스에 의해 다양한 원소를 동시에 스퍼터링 및 증착이 가능하도록 할 수 있다는 장점을 가지기 때문이다. 특히, 타겟의 미세구조를 나노구조화 하는것을 통해, 스퍼터링 yield의 차이가 큰 원소일지라도 균일하게 증착시킬 수 있는 방법을 개발하고자한다. 또한 다수의 타겟을 이용하여 균일한 다성분 코팅층 형성하는 기존의 PVD 코팅방법으로는 다수의 성분타겟을 사용함으로서 장비의 복잡성, 코팅의 재현성, 대형화 등의 문제점을 본질적으로 갖고 있다. 이를 위한 해결방법으로 본 발표에서는 3가지 이상의 다기능성 구현을 위한 가장 중요한 원천기술이라 할 수 있는 다성분계 타겟 모물질 제조 기술의 개발 진행 사항에 대해 소개하고자 한다.