• Journal of Sensor Science and Technology
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• v.5 no.2
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• pp.29-36
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• 1996

With the three dimensional magnetic field measuring system dealt with in this paper, accurate measurements and analyses of extremely low frequency(ELF) magnetic fields caused by starting and/or operating electric devices and power installations can be conducted. To obtain high performance for lower frequency and spatial components without any distortion, the measuring system is designed as three dimensionally including the multiturn loop-type magnetic field sensors, differential amplifiers and active integrators. As the results of calibration experiments, the frequency response characteristics of the measuring system range from 8[Hz] to about 53[kHz] for each direction of x, y, z axes, and the response sensitivities are 9.54, 9.21, $10.89[mV/{\mu}T]$, respectively. The actual survey experiments by using an oscillating impulse current generator confirm a reliability of the proposed measuring system. Also, through the other experiments by using small-sized induction motors, the magnetic field intensities when starting and steady-state operating mark 15.8, $8.61[{\mu}T]$ as maximum value, respectively. And those intensities decrease steeply according as the measuring distance increases.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.1
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• pp.22-30
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• 2011

In this paper, we propose a memory efficient multi-rate Low Density Parity Check (LDPC) decoder for China Mobile Multimedia Broadcasting (CMMB). We find the best trade-off between the performance and the circuit area by designing a partially parallel decoder which is capable of passing multiple messages in parallel. By designing an efficient address generation unit (AGU) with an index matrix, we could reduce both the amount of memory requirement and the complexity of computation. The proposed regular LDPC decoder was designed in Verilog HDL and was synthesized by Synopsys' Design Compiler using Chartered $0.18{\mu}m$ CMOS cell library. The synthesized design has the gate size of 455K (in NAND2). For the two code rates supported by CMMB, the rate-1/2 decoder has a throughput of 14.32 Mbps, and the rate-3/4 decoder has a throughput of 26.97 Mbps. Compared with a conventional LDPC for CMMB, our proposed design requires only 0.39% of the memory.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.89-95
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• 2007

This study was accomplished to compare energy saving effects of several heat insulation materials in greenhouse and to develop new automatic opening and closing equipment which is suitable to the most effective heat insulation material. To find out more effective heat insulation material, the magnitude of heat transfer occurred through aluminum screen (ALS), non-woven fabric (NWF), double-layer aluminum screen with chemical cotton sheet (DAL), and multi-layer fabric screen material quilted with non-woven fabric, chemical cotton, poly foam, and polypropylene (MLF) were compared relatively. The results showed that the relative magnitude of heat transfer occurred through MLF was lower than DAL and ALS by 23.3% and 43.0% respectively. MLF screen material was the most effective compared with other heat insulation materials. But because of thickness, there was a need of new mechanism for automatic operation in greenhouse. Accordingly, new screen system using MLF-thick but profitable for keeping warm in greenhouse-was developed. Opening & closing equipment was designed to roll MLF with pipe axis during opening process and pull MLF with string during closing process with electric motors, clutches, drums, and so on. In hot pepper cultivation and energy saving test during winter time, the early stage yield of pepper under MLF screen system was higher than NWF by 27%, and gasoline consumption of MLF screen system was lower than NWF by 46%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.473-480
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• 2011

The proton exchange membrane (PEM) fuel cell system is critically dependent on the humidity, which should be properly maintained over the entire operating range. A membrane humidifier is used for the water management in the PEMFC because of the membrane humidifier's reliable performance and zero parasitic power loss. In the PEMFC system, the membrane humidifier is required to provide appropriate humidity for the design point of the fuel cell. Although the performance of the fuel cell depends on the performance of the humidifier, few studies have provided a systematic analysis of the humidifier. We carry out an experimental analysis of the membrane humidifier using a vapor condensation bottle. The dry air pressure, water flow temperature, and air flow rate were chosen as the operating parameters. The results show that the time constant for the dynamic response of the membrane humidifier is relatively short, but additional analysis should be carried out.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.17-25
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• 2001

The purpose of this study is to substitute water-based painting materials for the current solvent-based ones used in motor-repairing process to minimize the exposure of organic solvents to the painters. This study assessed the exposure of organic solvents to the painters using water-based and solvent-based painting materials and compared compositions, painting processes and the health hazards of the application of these alternative painting mate rials. The results of this study are as follows. 1. solvent-based painting materials used in motor-repairing process consist of various organic solvents, which consist primarily of toluene, xylene, ethyl benzene, ethyl methyl benzene, trimethyl benzene, ethyl acetate, butyl acetate, methyl isobutyl ketone, 2-ethoxy ethanol, 2-ethoxy ethyl acetate and toluene-2,4-diisocianate and the others. These organic solvents are known as health-hazardous substances. But water-based painting materials are high-solid, low-solvent one sand consist of such two organic solvents as 2-butoxy ethanol and 2-heptanone and the others. 2. The painters us ing solvent-based painting mate rials in motor-repairing process are exposed to various organic solvents which consist of toluene, xylene, ethyl acetate, butyl acetate, methyl isobutyl ketone, trimethyl benzene, 2-ethoxy ethanol, and 2-ethoxy ethyl acetate. But the painters using solvent-based ones are only exposed to 2-butoxy ethanol and 2-heptanone. 3. By using water-based painting materials in stead of solvent-based painting materials containing health-hazardous organic solvents, the exposure of such organic solvents in the painter's breathing zone can be largely prevented. 4. This study recommends water-based painting materials as substitutes for the current solvent-based ones used in motor-repairing process to minimize the exposure of organic solvents to the painters.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.85-91
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• 2001

Background : It goes without saying that cumulative trauma disorders is spreading to various types of occupation in many advanced countries including America, and it forms considerable rate of total occupational disorders already. and as the result of it, the seriousness of worker health problem and economic loss owing to production loss, recuperation expense, etc. are on the increasing trend through whole society. In case of Korea, the related measures as well as accurate fact-finding survey data on cumulative trauma disorders aren't prepared in detail, so it implies forward problem would be serious. Purpose : The purpose of this study is to draw the risk factor of cumulative trauma disorders in production factory, to forecast the rate of occurrence of cumulative trauma disorders on the basis of subjective symptoms, and to present forward realistic and effective prevention measures by showing the risk of cumulative trauma disorders, objecting the production factory of a domestic riding automobile assembly shop, by estimating in the aspect of human-engineering through the analysis of risk factor being a cause of cumulative trauma disorders. Methods : For this study, I investigated work type and on-duty hours, breathing time, and subjective symptoms of cumulative trauma disorders through questionnaire, objecting the workers in press. car body, coating, and outfit factory. Results : As a result of research, 81.2% of workers were in the physical burden due to present working, and the highest prevalence by part of body is an waist. The higher a rule score, The higher the number of workers complaind for working intensity, and the higher age work duration, tool used time, the higher prevalence of subjective symptoms by part of body. The number of workers complaind subjective symptom for treatment is the highest in drugstore.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.4
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• pp.310-317
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• 2008

The objective of the survey is to define and judge exposure profiles semi-qualitative data in high risk processes using styrene. The survey was conducted on 98 factories out of 229 factories based on data from periodic working environment monitoring for styrene. Styrene is widely utilized as a raw material for PS and co-polymers such as ABS, SAN, SBR, SBL, unsaturated polyester resins(UPR) and others. An approximate breakdown of styrene's markets in Korea is PS 30%, expandable PS 17%, ABS 33%, SAN 5%, SBL 4%, SBR 3%, UPR 1% and other 7%. Although UPR accounts for 1% of total amount of styrene, workers dealing with it are exposed to very high concentrations up to 64 ppm. Especially styrene is widely used in the laminating process of fiberglass reinforced plastics(FRP) manufacturing industry. The Applications using styrene are largely classified into two sections which are applied to styrene monomer(SM) and UPR. SM is utilized for a raw material of resins, surfactant and adhesive. UPR is employed for FRP and non-FRP. For SM control targets are mixing colors and packing in the gelcoat resins manufacturing industry(MI), for UPR control targets out of works using UPR are 1) laminating in the MI of plastics, automobile parts and boats, 2) mixing and packing in the SMC/BMC MI, 3) molding and cutting in the other specific plastics MI, 4) mixing and coating in artificial marble product MI, 5) dipping in the electric motors & transformers MI, 6) molding in the button MI, 7) painting in the musical instrument MI. Findings from the study have given the information for the high risk processes and working practices so that occupational health professionals could focus on targeted workplaces to prevent occupational diseases. It is also useful to develop a control strategies and specific controls for high risk processes and facilities using styrene.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.421-428
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• 2006

Systematic improvement of the environmental performance of industrial products is a core element of good business. Improving the overall environmental performance of products is envisaged as one of the most important strategic goals and objectives in many company policies. This paper demonstrates an Ecodesign approach to develop a product in a systematical way. The objective of this research is two-folds-describing a systematic procedure of implementing Ecodesign in a company and giving a real case example to demonstrate the application of the proposed Ecodesign methodology. The methodology was based on Wimmer et al and consists of seven steps out of the twelve steps for integrating significant environmental aspects of a product and environmental issues resulting from the stakeholder requirements into product design and development. Together with the Ecodesign team of a major domestic car manufacturer the Ecodesign of a car fuel tank unit has been chosen for the case study presented in the paper. The application of the proposed methodology to the fuel tank unit of a car indicates that practical target specifications of the fuel tank unit were derived systematically. This indicates that the seven steps approach can be a viable Ecodesign method for manufacturers to integrate environmental aspects of their products into their product design and development processes.

• Archives of design research
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• v.19 no.5 s.67
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• pp.363-372
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• 2006

The aim of this study is to shed light on the importance of female drivers, study their characteristics and needs, and create automobile designs in accordance with the study. The power of female consumers is greatly increasing in a modern society, To the extent that women became the core consumers. Companies are now turning their attention to female consumers in order to survive the fierce competition in the saturated markets. Moreover, it is becoming imperative for companies to actively develop products and services in female perspectives to meet the diversified needs of consumers. It is forecasted that vigorous research, analysis and understanding of the unique culture of women will be increasingly important now that women are emerging as core consumers. Only the companies that makes such efforts consistently can dominate the market. The automobile industry is not an exception. The world's major automobile companies including Volvo and Ford Motor Co. are keenly focusing on automobile exterior and interior designs for women. Korean companies are also designing cars that cater to women, starting with Lanos and Juliet of Daewoo Motors in 1998, yet specific and systematic research on the subject has not been made. This study aims to emphasize the power of female users, make a research and analysis on their needs and characteristics, and suggest car interior designs that cater to them.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.194-201
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• 1998

In electric commuter trains using AC motors, lots of GTO thyristors and diodes are needed for power controls. These semiconductors generate heat about 1~2 kW, and for cooling which perfluorocarbon(PFC) heat pipes have been in use for the last two decades. The present study was investigated on the effects of such important design parameters as structure of internal surface (grooved or smooth), fill charge ratio, and inclinating angle from a vertical on heat transfer coefficients at both evaporators and condensers. To obtain experimental data, several heat pipes of the same geometry of 520 mm long and diameter of 15.88 mm but different in fill charge ratio and internal surface structure were designed and fabricated. For prediction of the heat transfer coefficients, related expressions were examined and the results of calculations were compared with experimental data. Performance tests were conducted while heat pipes operated at mode of thermosyphons. High enhancements of heat transfer coefficient were obtained internal grooves. In these cases, the evaporating heat transfer coefficients distributed in the range of 2~5.5 kW/$m^2$K, with an increase of heat flux from 15~45 kW/$m^2$. These experimental data were in good agreement with Rohsenow's expression based on nucleate boiling when correction factor $C_R$=1.3 was encountered. In addition, the condensation heat transfer coefficients were distributed from 1.5 to 3.5 kW/$m^2$K, and the data were in good agreements with Nusselt's correlation, based on filmwise condensation on vertical plate, when choosing a correction factor $C_N=4$. A fill charge ratio of 40~100% were recommended, and the in clination angle effects were negligible when the angle was higher then 30$^{\circ}$.