• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.240-253
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• 1996

The refrigeration cycle of automobile air-conditioners is simulated in an effort to provide a computational tool for optimum thermodynamic design. In the simulation, thermodynamic and heat transfer analysis was performed for the four major components : evaporator, condenser, compressor, and expansion valve. Effectiveness-NTU method was used for modeling both evaporator and condenser. The evaporator was divied into many subgrids and simultaneous cooling and dehumidifying analysis was performed for each grid to predict the performance accurately. Blance equations were used to model the compressor instead of using the compressor map. The performance of each component was checked against the measured data with CFC-12. Then, all the components were combined to yield the total system performance. Predicted cycle points were compared against the measured data with HFC-134a and the deviation was found to be less than 5% for all data. Finally, the system model was used to predict the performance of CFC-12 and HFC-134a for comparison. The results were very reasonable as compared to the trend deduced from the measured data.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.4
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• pp.235-245
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• 1979

The land utilization of Korea composed about 22.7% of arable land, 66.9% of forest land and 10.4% for the rest like a house site, road, and lake etc. The ratio of arable land is too small as compared with forest land which is occuping two-thirds of Korea. The expansion of arable land by the reclamation will solve the food problems for increasing populations. First, we have to know the exact extents and distribution of reclaimable land but the reported total extent of reclaimable land in Korea is variable according to the authority which carried out the soil survey. The different reported data of reclaimable land is owing to the method and criteria of soil survey. 840,522ha in Land Capability Survey of the Farm Land Improvement Association and 321,203ha in the Forest Land Survey by the Office of Forest was reported but the Office of Rural Development said that total reclaimable land was 1,400,540ha including grazing and fruit land. To assume the extent of reclaimable land, the soil survey method and criteria of soil survey should be considered. It can be considered that the main reasons of less in extent of reclaimable land in the other authorities than the Office of Rural Development is due to the following. The grazing land and the fruits land are not included by the Farm Land Improvement Association and only relative forest is considered by the Office of Forest. The main purpose of soil survey carried out by the Office of Rural Development is to utilize land of Korea at most. The soil characteristics and potential productivity are considered in soil survey and the reported data was based on reconnaissance soil survey. The more accurate data will be find out by the end of 1979 when the detailed soil survey will be done. In selection of cropping system and management, the soil condition should be considered, because the soil characteristics of reslaimed land is less fertile than the arable lands.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.29-32
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• 2000

In this paper, we present an extension of the multi-code CDMA (code division multiple access) systems based on bi-orthogonal modulation by employing a convolutional encoder and an interleaver before serial-to-parallel conversion in the modulator. Bandwidth expansion by the convolutional encoder can be compensated for by the bi-orthogonal modulation, and the interleaver in the system scrambles the convolutionally encoded data bits so that, after serial-to-parallel conversion, each code channel conveys those bits far apart in time. The result is that the proposed system with several order of magnitude less implementational complexity, achieves quite close performance of the conventional systems comprised of Walsh modulation and multiple convolutional encoders and interleavers in all the code channels.

• International Journal of Concrete Structures and Materials
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• v.9 no.4
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• pp.463-473
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• 2015

Three full-scale instrumented test slabs were constructed and tested using a heavy vehicle simulator (HVS) to evaluate the structural behavior of internally cured concrete (ICC) for use in pavements under Florida condition. Three mix designs selected from a previous laboratory testing program include the standard mixture with 0.40 water-cement ratio, the ICC with 0.32 water-cement ratio, and the ICC mixture with 0.40 water-cement ratio. Concrete samples were prepared and laboratory tests were performed to measure strength, elastic modulus, coefficient of thermal expansion and shrinkage properties. The environmental responses were measured using strain gages, thermocouples, and linear variable differential transformers instrumented in full-scale concrete slabs. A 3-D finite element model was developed and calibrated using strain data measured from the full-scale tests using the HVS. The results indicate that the ICC slabs were less susceptible to the change of environmental conditions and appear to have better potential performance based on the critical stress analysis.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.11a
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• pp.205-208
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• 2006

This research investigated the public rental houses In Yangchon-gu, whose locational attribute are suitable for the public rental house and has superior position in both inhabitants' participation and public welfare program. The public rental house has several types, such as permanent lease house, public lease. And several programs, the aged support police and medical services delivery system, have been the leading models for other local governments. Also, there are residents who are in their forties and fifties in the public rental houses in Yangchon-gu. un occupied is less than 1% and it seems that there is few turnover rate. 1 household rate and 2 households rate look like similar in the number of family member, total social public welfare program is focus on family welfare, juvenile welfare, teenager welfare, handicapped person welfare local, welfare and old people welfare. Accordingly, this research is used for base data of questionnaire and the first data for grope various improvement while planning group public rental house for low income group. And this research will be improved directional grope for improve livable public rental house around residents.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.661-669
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• 2013

River-water quality has been greatly improved during past several decades with the extraordinary expansion for the wastewater treatment capacities by the government. Research aims to select the priority restoration streams based on the chronicle data for tributaries in Geumgang watershed as the main stream area in the Chungchungnamdo province. The quality of BOD, phosphorus and percent of sewered population on 15 branch streams were compared by the grouping methods. The results of group D streams by category I that exceed 3.0 mg/L for BOD and 0.1 mg/L for phosphorus were Seuksung, Ganggyung and Bangchuk stream. The results of group D streams by category II that exceed 3.0 mg/L for BOD and less than 63.5 % of average percent of sewered population were Ganggyung, Gilsan, Bangchuk and Seuksung stream. The final results of selected streams drawn by the chronicle data which exceeded the standard quality and lower than the average percent of sewered population were Seoksung, Gangeyung and Bangchuk stream. The pollution of rivers in the down streams were more serious than in the upper streams. Their watersheds have to be improved river water quality, especially to extend sewer systems as well as wastewater treatment facilities.

• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.317-330
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• 2022

Recently, the policy regarding climate change in Korea and overseas has been to promote the utilization of forest biomass to achieve net zero emissions. In addition, with the implementation of the unused forest biomass system in 2018, the size of the Korean market for manufacturing wood pellets and wood chips using unused forest biomass is rapidly expanding. Therefore, it is necessary to estimate the total amount of unused forest biomass that can be used as an energy source and to identify the capacity that can be continuously produced annually. In this study, we estimated the actual forest area that can be produced of logging residue and the potential amount of unused forest biomass resources based on GT (green ton). Using a forest functions classification map (1 : 25,000), 5th digital forest type map (1 : 25,000), and digital elevation model (DEM), the forest area with a slope of 30° or less and mountain ridges of 70% or less was estimated based on production forest and IV age class or more. The total forest area where unused forest biomass can be produced was estimated to be 1,453,047 ha. Based on GT, the total amount of unused forest biomass potential resources in Korea was estimated to be 117,741,436 tons. By forest type, coniferous forests were estimated to be 48,513,580 tons (41.2%), broad-leaved forests 27,419,391 tons (23.3%), and mixed forests 41,808,465 tons (35.5%). Data from this research analysis can be used as basic data to estimate commercial use of unused forest biomass.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.6
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• pp.709-734
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• 2001

The aims of this experiment were to investigate the strain and temperature changes simultaneously within autopolymerzing acrylic resin specimens. A computerized data acquisition system with an electrical resistance strain gauge and a thermocouple was used over time periods up to 180 minutes. The overall strain kinetics, the effects of stress relaxation and additional heat supply during the polymerization were evaluated. Stone mold replicas with an inner butt-joint rectangular cavity ($40.0{\times}25.0mm$, 5.0mm in depth) were duplicated from a brass master mold. A strain gauge (AE-11-S50N-120-EC, CAS Inc., Korea) and a thermocouple were installed within the cavity, which had been connected to a personal computer and a precision signal conditioning amplifier (DA1600 Dynamic Strain Amplifier, CAS Inc., Korea) so that real-time recordings of both polymerization-induced strain and temperature changes were performed. After each of fresh resin mixture was poured into the mold replica, data recording was done up to 180 minutes with three-second interval. Each of two poly(methyl methacrylate) products (Duralay, Vertex) and a vinyl ethyl methacrylate product (Snap) was examined repeatedly ten times. Additionally, removal procedures were done after 15, 30 and 60 minutes from the start of mixing to evaluate the effect of stress relaxation after deflasking. Six specimens for each of nine conditions were examined. After removal from the mold, the specimen continued bench-curing up to 180 minutes. Using a waterbath (Hanau Junior Curing Unit, Model No.76-0, Teledyne Hanau, New York, U.S.A.) with its temperature control maintained at $50^{\circ}C$, heat-soaking procedures with two different durations (15 and 45 minutes) were done to evaluate the effect of additional heat supply on the strain and temperature changes within the specimen during the polymerization. Five specimens for each of six conditions were examined. Within the parameters of this study the following results were drawn: 1. The mean shrinkage strains reached $-3095{\mu}{\epsilon},\;-1796{\mu}{\epsilon}$ and $-2959{\mu}{\epsilon}$ for Duralay, Snap and Vertex, respectively. The mean maximum temperature rise reached $56.7^{\circ}C,\;41.3^{\circ}C$ and $56.1^{\circ}C$ for Duralay, Snap, and Vertex, respectively. A vinyl ethyl methacrylate product (Snap) showed significantly less polymerization shrinkage strain (p<0.01) and significantly lower maximum temperature rise (p<0.01) than the other two poly(methyl methacrylate) products (Duralay, Vertex). 2. Mean maximum shrinkage rate for each resin was calculated to $-31.8{\mu}{\epsilon}/sec,\;-15.9{\mu}{\epsilon}/sec$ and $-31.8{\mu}{\epsilon}/sec$ for Duralay, Snap and Vertex, respectively. Snap showed significantly lower maximum shrinkage rate than Duralay and Vertex (p<0.01). 3. From the second experiment, some expansion was observed immediately after removal of specimen from the mold, and the amount of expansion increased as the removal time was delayed. For each removal time, Snap showed significantly less strain changes than the other two poly(methyl methacrylate) products (p<0.05). 4. During the external heat supply for the resins, higher maximum temperature rises were found. Meanwhile, the maximum shrinkage rates were not different from those of room temperature polymerizations. 5. From the third experiment, the external heat supply for the resins during polymerization could temporarily decrease or even reverse shrinkage strains of each material. But, shrinkage re-occurred in the linear nature after completion of heat supply. 6. Linear thermal expansion coefficients obtained from the end of heat supply continuing for an additional 5 minutes, showed that Snap exhibited significantly lower values than the other two poly(methyl methacrylate) products (p<0.01). Moreover, little difference was found between the mean linear thermal expansion coefficients obtained from two different heating durations (p>0.05).

• Journal of the Korean Society of Food Culture
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• v.30 no.2
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• pp.190-196
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• 2015

Restaurants implement menu labeling to provide nutritional information to customers in an attempt to help customers select healthy menu items. Considering the increase in food-away-from-home consumption, the purpose of this study was to identify motivators and barriers in restaurant customers regarding use of menu labeling. Data were collected from a survey on restaurant customers in Seoul, Korea. The findings of this study indicate that customers used menu labeling for health reasons. However, barriers to using menu labeling were identified as small font size, difficulty in locating nutritional information display, and difficulty in interpreting nutritional information. In addition, they also suggested expanding the scope of menu labeling for restaurants by including chain restaurants with less than 100 units. The findings of this study offer strategies for the government to improve menu labeling practices for customers.

• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.131-136
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• 2006

Most modern railways, especially the high speed railway tracks, use continuous welded rail(CWR) for the less maintenance. For the CWR track has very few expansion joints, track buckling has always been an unpredictable event and it happens mainly by high compressive stress in rail in summer period. Therefore, it is important to understand the variation of rail stress induced by thermal loads which has direct influence on the rail buckling and stability of railway track. This paper describes the experimental investigation of the variation of rail temperature and stress in a high speed railway track on bridge structure. Field measurement was performed to examine the correlation between the rail temperature and rail stress on the Korean High Speed Railway line. Regression functions were derived from measured data to determine the rail stress f3r an arbitrary rail temperature varies from 20 to 50 degree Celsius.