• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.57-64
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• 2016

Power demand has continuously increased with technological and economical development. The load density is also growing in the center of downtown area. In particular, underground facilities have been increased on the purpose of the prevention of urban disasters and pedestrian environment improvement. Based on this situation, the underground space in urban surroundings has gradually decreased because of the limited space. The ampacity of buried cables is affected by various factors such as cable size, soil thermal resistance, burial depth and filling material. The thermal capacity of the facilities is determined by the absorb heat surrounding the cable and the soil. The maximum operating temperature of cable is the highest temperature when the insulator of cable is not damaged in the case of high enough temperature. In this paper, the most effective cabling configuration is suggested using the duct array adjustment. It was also considered to increase the number of cable line. This underground distribution system was simulated by using ETAP(Electrical Transient Analysis Program).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.94-105
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• 2016

The objective of the work was to evaluate the impact of lighting energy to cooling and heating consumption in medium scale office building, when currently installed fluorescent lights were replaced with various LED lighting fixtures. This evaluation comes from an integrated approach combining the proper indoor lighting environment and the thermal aspects of cooling & heating consumption in office building. These simulations were performed by coupling an appropriate luminaire analysis for energy consumption and a dynamic thermal simulation software (TRNSYS). To analyze comparative study of effects on the heating, cooling loads, and energy consumption of an LED lamp application, 2 types of LED lamp with low light power watt(LPW) 24W and high LPW 7.5W and a fluorescent lights(FL) with 37W are used respectively. Integrated building energy consumption decreased up to 3.2% when fluorescent lamps were replaced with LEDs. Thus, the high LPW of LED(7.5W) replaced with the same number of FL shows an effective energy saving and cost- effective luminary.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.1-9
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• 2007

This study proposes to increase the energy-saving effects by reducing excessive intensity of radiation of artificial lighting through analyzing daylight incident. A photosensor sends amounts of detected luminous flux to digital control unit(DCU) as a signal and then, it can decide dimming ratios, received a proper dimming signal from DCU. Generally it is effective to control artificial lighting with the different control ratio of each zone by setting a photosensor as same number and rows as artificial lighting. However, it is ineffective to do in initial costs of systems aspect in offices. As a result of grasping the distribution of daylight previously and analyzing daylight and dimming data, we can dim different dimming ratios to each zone of artificial lighting by a single photosensor.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.92-99
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• 2013

The ratio of mobility handicapped was 12,110,000 in late 2009 about 24.4% of total population. The number of handicapped population is increasing continuously due to traffic accidents and industrial disasters. Therefore, the purpose of this research is to suggest a design for passengers on wheelchairs to get into and off to raise handicapped or elderly people's right of mobility. The scope of this research is mobility handicapped especially wheelchair passengers who use vans, small buses, and trains. The ramp design of vans is module form. The ramp is moved with screw jack and guides are installed on each side to increase stability. Moreover, a bridge was installed for smooth getting in and off of the van. The ramp design for small bus is lowed by 200m in order not to have obstacle such as speed bump when getting in or off. In order to reduce vulnerable environment and administration, air slide cylinder was chosen. Lastly, for the ramp design of train, the principle of link was used that the simpler structure made the weight lighter and installation in the train became easier. If we look at the conjugation condition of heterogeneous materials to produce a ramp, proper welding condition for cold steel plate and stainless plate is 3kW output and 3-5m/min of welding speed using laser beam seems proper.

• Land and Housing Review
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• v.10 no.3
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• pp.17-22
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• 2019

In recent years, crime has been steadily increasing, causing not only economic damage but also aggravating the social atmosphere. The CPTED(Crime Prevention Through Environmental Design) guideline, which is an environmental crime prevention design technique, reduces the possibility of crime by implementing a proper defensive design plan through appropriate lighting design in the city and reduces the fear of crime. Among the various principles of CPTED, the proper use of street lamps and CCTV is considered to be an important factor in enabling natural surveillance. In this study, the authors identified and quantified the current status of the installation of street lamps and CCTV in each autonomous district of Seoul. The physical quantity of lighting and social factor quantified from light lamps and CCTV data, respectively, were expected to support the guidelines presented by CPTED. Therefore, we conducted statistical analysis based on quantified values and found that street lamps and CCTV had a statistically significant relationship with crime rate. In addition, the correlation between the safety index and the crime rate, calculated by dividing the number of street lamps and CCTVs by area, was also analyzed and an R2 value of 0.647 was confirmed.

• Geomechanics and Engineering
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• v.11 no.1
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• pp.41-58
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• 2016

This paper focuses on the deformation behavior of tunnels crossing a weak zone in conventional tunneling. A three-dimensional finite element model was adopted that allows realistic modeling of the tunnel excavation and the support installation. Using the 3D FE model, a parametric study was conducted on a number of tunneling cases with emphasis on the spatial characteristics of the weak zone such as the strike and dip angle, and on the initial stress state. The results of the analyses were thoroughly examined so that the three-dimensional tunnel displacements at the tunnel crown and the sidewalls can be related to the spatial characteristic of the weak zone as well as the initial stress state. The results indicate that the effectiveness of the absolute displacement monitoring data as early warning indicators depends strongly on the spatial characteristics of the weak zone. It is also shown that proper interpretation of the absolute monitoring data can provide not only early warning for a weak zone outside the excavation area but also information on the orientation and the extent of the weak zone. Practical implications of the findings are discussed.

• Journal of Environmental Health Sciences
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• v.37 no.6
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• pp.460-466
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• 2011

Objectives: Students in elementary schools usually wash their hands in a washstand. However, little attention is paid to the washstand itself. Today, the importance of personal sanitation and hygiene is greatly emphasized. Therefore students' parents and the public are growing increasingly interested in accessibility to washstands by elementary school students in their schools. Methods: With respect to this study, a survey of students and teachers inelementary schools was performed on the installation of washstands in order to determine the proper number of washstands per school. Results: The results show that 1.1 boys (per class) need a washstand, while 1.8 girls (per class) do so in order to maintain a 50% level of crowdedness. By of the regression equation, to maintain 50% congestion (50% of all students feel congestion) there should be 18.5 boys, and the 15.76 girls per washstand. Table 3 is based on the above results, the number of students per washstand (x) and congestion (y), separated by gender according to the results of regression analysis, the correlation of male models in the linear regression analysis and correlation of girls in the regression equation can be obtained. The linear regression fit of less than 0.7 determines that the coefficients of determination are 0.5399 and 0.4195, respectively. Significance was much smaller. Also, according to the simulation using the diffusion model, with 29 students per class more than one washstand should be provided in a school. Girls (per class) need 0.7 more washstands than boys (per class). Conclusions: More washstand facilities for girls than boys are needed. If the target is based on school class size two washstands should be installed. Finally, guidelines and/or standards in the Schools Health Act of Korea forin elementary school washstands is considerably needed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.807-811
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• 2011

When the high voltage motor fails in power plants, there will be an occurrence where the generator's output would be reduced or the generators would trip. Despite of these effects, the causes of deterioration of the high voltage motor is very seldom investigated. In this paper, the collected data which tested in the field over 10 years have been treated statistically, and analyzed to correlate the insulation deterioration of high voltage motor and installation environment, number of start/stop, and service life. Moreover, the proper period of insulation test is developed to map out maintenance strategy and reduce maintenance costs.

• Journal of the Korean Solar Energy Society
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• v.33 no.6
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• pp.85-91
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• 2013

It is essential to reduce the amount of fossil fuel because facing with the natural problem such as a global warming. To achieve this goal, many of interests in the use of renewable energy is growing. Especially, as one of these renewable energy systems, a solar air heater invention has been conducted for enhancing the efficiency of solar air heater. According to this trend, scale-down sized experiment apparatus was constructed and performed for searching a proper fin and confirming the heat transfer performance by fin shape on constant heat condition to enhance efficiency of solar air heater. In this experiment, heat gain, convection heat transfer coefficient, number of transfer units, Nusselt number, Reynold's number, friction factor, performance factor were investigated in order to evaluate the thermal characteristics based on the real data obtained. By comparison with the each fin performance, a zigzag shape keeping a right angle to the plate had the highest value among them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.895-906
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• 2018

The improvement project for school zone in Korea is occurring mostly in kindergartens and elementary schools in which children are mainly active, and is being promoted as part of measures to prevent children's traffic accidents. However, since the study on the essential installation facilities and proper level of safety facilities for School zone is lacking, this study relatively evaluated the efficiency of safety facility installation using DEA (Data Envelope Analysis) and suggested improvement plan. We built the facilities and incident data for 28 school zones in Hwaseong City. Six major facilities (Raised intersection, Raised crosswalk, Protective fence, Skid Proof, Speed hump, Speed cameras) that have proven to be effective in the preceding research were analyzed as input factors. As a result of the analysis, only 12 out of 28 showed efficiency and 16 out of efficiency. Effective groups of school zones were found to have fewer installed Protective fences, Skid Proof, and Speed cameras installations than school zones classified as ineffective groups. Protective fences were found to be efficient even if only 47% of the total extension of the school zone was installed, and the number of slip prevention facilities was 8.7 per square km. The number of subjects to be compared is 28, so this study is limited to use as a relative efficiency evaluation index, and it can be grouped into nationwide units and efficiency evaluation can be done for each group.