• Title/Summary/Keyword: machinery and metal industry

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Effect of Heat Treatment on High Temperature Fatigue Strength Characteristics of STB2 Bearing Steel (STB2강의 고온피로강도 특성에 미치는 열처리의 영향)

  • Oh, Sae-Kyoo;Kim, Yeon-Ho;Lee, Sang-Guk;Lee, Jong-Du
    • Journal of Ocean Engineering and Technology
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    • v.3 no.2
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    • pp.138-144
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    • 1989
  • It has been very important in various industry fields to improve the fatigue strength characteristics of bearings such as bearing life, fatigue limit, etc., because such poor properties could result in shortening the machinery life as well as in decreasing the accuracy. However, no successful heat treatment criterion seems to be available at present. In this study, the effect of the $170^{\circ}C\times120min$ tempering cycles repeated after $380^{\circ}C\times80min$ oil quenching for $800^{\circ}C$ spheroidizing-annealed bearing steel (STB2) as base metal on the $120^{\circ}C$ high temperature rotary bending fatigue strength characteristics were investigated, including the effects on hardness, Charpy impact value and micro-structure, in order to seek for the best heat treatment condition finally. The important results obtained are as follows : 1) The optimal cycle of tempering so that the fatigue strength .sigma. could become the highest was the 4th cycle. And it is confirmed that this $\sigma_{F}$ is about 6 times more increased than that of base metal, and about 1.3 times more increased than the case of the 1 cycle tempered. 2) As a result of the investigation for the effects of tempering cycles on hardness, the hardness at the tempering number of 2 thru 5 cyles was not decreased severely ; only about 10% decrease from those of the quenched and 1 cycle tempered case. Such hardness is equivalent to $H_{R}$/C61-62 with no bad effect on anti-abrasion of bearing steel. 3) In the case of 2 thru 5 cycle tempering as well as 1 cycle tempering, the impact value was not so improved comparing with the case of quenching, but an increase of 5 to 10% could be expected at least. 4) It was experimentally confirmed that the control of the mechanical properties improvement such as fatigue strength and fatigue life for bearing steels could be possible by the number of tempering cycles.

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The Impact of Enterprise R&D Investment on Inter-industry Technology Spillover in Korea under the new Normal Era (뉴 노멀 시대하 한국기업의 R&D투자가 산업간 기술파급에 미치는 영향)

  • Kim, Seon Jae;Lee, Younghwa
    • The Journal of the Korea Contents Association
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    • v.13 no.2
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    • pp.390-399
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    • 2013
  • The purpose of this study is to examine the impact of enterprise R&D investment on inter-industry technology spillover in Korea under the new Normal Era. In order to do this, we tested the effect of production inducement, backward and forward linkage effects, and the effect of technology spillover such as technology intensity effects and technology diffusion effects based on an input-output framework. The results show that the high index industries of the production inducement effect were professional, scientific and technical activities, manufacture of metal products, and general machinery. Some manufacturers of other non-metallic mineral products and transport equipment sectors appeared to have the strong effect of forward and backward linkages that were almost equivalent to high-tech manufacturing industries. In particular, the industries of professional, scientific and technical activities appeared to have the strong effect of both forward and backward linkages. Therefore, we need to drive a strong policy support to higher enterprise R&D investment in the those particular industries not only to increase global competitiveness, but also to widen up the technology spillover effect on other industries.

Pollution Characteristics of Hazardous Elements for Roadside Dust in Gwangju City, Korea (광주광역시 도로변 분진에 대한 유해원소의 오염특성)

  • Lee, Jang-Jon;Park, Young-Seog;Kim, Jong-Kyun;Han, Min-Su
    • Economic and Environmental Geology
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    • v.40 no.3 s.184
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    • pp.263-275
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    • 2007
  • The purpose of this study was to show the pollution characteristics of hazardous elements from roadside dust in the Gwangju city. We collected 47 samples from November to December in 2004 and separated four groups such as residential area, industrialized area, downtown area and heavy traffic area fer characteristics comparison on hazardous elements. Roadside dust mostly consisted of quartz, albite, microcline, muscovite in XRD analysis. Content of hazardous elements varied: As $3.4{\sim}11.9 ppm$, Cd $0.2{\sim}28.2 ppm$, Co $32{\sim}526 ppm$, Cr $25{\sim}526 ppm$, Cu $11{\sim}375 ppm$, Ni $14{\sim}247 ppm$, Pb $13{\sim}413 ppm$ and Zn $101{\sim}972 ppm$. Average contents of hazardous elements of Zn>Cu>Pb>Cr>Co>Ni>Cd. Content of hazardous elements was low in residential area, whereas that of heavy metal was much the same in both in heavy traffic area. Content of hazardous elements such as Cd, Co, Cr, Cu, Ni, Pb, Zn was found to be particularly high in industrialized area. According to these results it was possible to presume that industrialized area was affected by industry activity such as machinery, petrochemical, automobile and electronics industry. The SEM analysis, detected Pb, Cr, Ni, and Fe particles in samples of industrialized area contaminated by industry activity. The correlation coefficient table resulted from the samples of roadside dust showed that there was same direction increase of content between elements. In other words, when the content of Cd increase, Cr and Ni increase, as Cr increase, Cu and Ni increase, as Cu increase Ni increase and Pb increase Zn increase. Based on these results it was possible to predict and interpret similar contamination patterns in this study.

Assessment of Technology-Based Industrial Wastewater Effluent Limitations and Standards for the Application in Domestic Industries ( I ) : Case-study, Applying TBELs in US (처리기술에 근거한 산업폐수 배출허용기준 국내 적용성 연구( I ) : 미국 TBELs 적용사례 검토)

  • Kim, Kyeongjin;Son, Daehee;Her, Jin;Kim, Kwangin;Kwon, Osang;Yeom, Ictae
    • Journal of Korean Society on Water Environment
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    • v.26 no.1
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    • pp.1-9
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    • 2010
  • Technology-Based Effluent Limitations (TBELs) is a permit limits for a pollutant that is based on the capability of a treatment technology to reduce the pollutant to a certain concentration. Widely practiced for regulations of industrial wastewater in US, TBELs has been accepted as an effective means that can achieve balanced goals between complete elimination of pollutants discharge and economic feasibility for industries. The review of TBELs application in US and the applicability of TBELs to the domestic industry categories was given in three papers. In the first paper, the development and practices of TBELs in US were reviewed including case studies. The developments of TBELs in US in the four major categories, the metal products & machinery, the petroleum refining, the porcelain enameling and the meat & poultry products were reviewed. The applicability of TBELs to the domestic industrial categories was also assessed. In the second paper, the pollution loads analysis for domestic industrial wastewater was conducted based on risk assessment indicator using Toxic Weighting Factors (TWFs). This is an essential part to determine the priority of TBELs application for the domestic industrial categories. In the last paper, the application of TBELs to the domestic industries was demonstrated through a case-study for the pulp/paper/paperboard category. Direct application of TBELs of US into the Korean regulation system may not be desirable because the specific goals and the environment for the regulations for the two countries may not be identical. For example, unlike US, Korea does not adopt the individual permit system for pollution sources. However, among the unproductive and exhaustive controversies over the uniform regulations regardless of the industrial categories in Korea, the introduction of the principles of TBELs are inevitable and more extensive study for applications of TBELs optimized for Korean regulation system will be necessary.

New demand forecast for vocational high school graduates in regional strategic industries: Focusing on comparison between Daejeon and Jeonnam (지역전략산업에 따른 특성화고 졸업자 신규수요 예측: 대전과 전남 지역 비교를 중심으로)

  • Kim, Jin-Mo;Choi, Su-Jung;Jeon, Yeong-Uk;Oh, Jin-Ju;Ryu, Ji-Eun;Kim, Seon-Geun
    • Journal of vocational education research
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    • v.36 no.1
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    • pp.47-75
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    • 2017
  • The purpose of this study was to provide basic data for policy making for secondary vocational education in each region and transformation in vocational high schools. To achieve this, the regional strategic industries in Daejeon and Jeonnam were selected, new demand for vocational high school graduates was forecasted in each industry and occupation. The results of the study are as follows. First, locational quotient analysis and regional shift-share analysis revealed that Daejon and Jeonnam have different strategic industries. Daejon, unlike Jeonnam strategically develops 'manufacturing food, beverage and tobacco', 'manufacturing timber and paper, printing and copying', 'public service and administration of national defense and social security' and 'manufacturing electrical devices, electronics and precision devices'. Jeonnam has specialized industries distinguished from Daejon's, which are 'manufacturing of machinery transportation equipments and etc', 'manufacturing of non-metallic minerals and metal products', 'electric, gas, steam and water supply systems/industries', 'manufacturing coal and chemical products, refining petroleum', 'mining' and 'agriculture, forestry and fishery'. Second, new demand for vocational high school graduates by occupations and industries showed regional differences(in Daejon and Jeonnam). According the forecast, Daejon will have many workforce demands based on manufacturing industries, on the other hand Jeonnam's focused on service industries. Analysis by occupations was also different, Daejon showed high demands on professional and related workers, while Jeonnam requested many new office and service workers. Third, new workforce demand by occupations in regional strategic industries is big part of overall new workforce demand both in Daejon and Jeonnam. Forth, according to the results of analyzing the new demand for vocational high school graduates in Daejeon and Jeonnam in terms of industry location quotient and change effect, there was high demand in industries with positive total change effects. In terms of location quotient, Daejeon and Jeonnam showed different results.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.