• International Journal of Contents
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• v.14 no.4
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• pp.65-69
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• 2018

The objective of this study was to conduct a radiation shielding analysis for the facility equipped with radiation generator. The analysis was carried out in two aspects. First, from the aspect of the effect caused by primary and leakage radiation. Second, effect of scattered radiation was evaluated by applying a simple calculation method based on a scattering rate concept since effect of scattered radiation is significantly important at maze entrance of the radiation facility. The calculated results obtained using the simple method were compared to the results calculated using Geant4 code and the measured values. The results calculated by the suggested method indicate that slight error exists in a radiation shielding analysis done at the maze entrance comparing to other two results, while the results evaluated at the outside of the maze entrance door are relatively consistent with other values.

• Journal of the Korean Society of Visualization
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• v.10 no.2
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• pp.20-24
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• 2012

Increasing the active catalyst surface area is important in improving a converter's efficiency. In addition, uniform flow is advantageous in that it produces more efficient catalytic conversion. This results in the ability to use a smaller catalytic converter with uniform flow as opposed to a larger converter requirement for non-uniform flow. Therefore, it is important to characterize the internal flow of the catalytic converter. To characterize the system's flow patterns, velocity measurements were taken at the mid and exit planes of a ceramic honeycomb catalytic converter at flow rates of 37.8 l/s and 94.4 l/s. Measurements were conducted using LDV. The profiles were measured along both the major and minor axis of the planes. Primary flow direction velocities measured along the minor axis, at both flow rates, varied greatly at the mid plane and somewhat at the exit plane. The areas of greatest air flow were seen near the edges of the walls and on the side of the converter opposite the flow's entrance region. It also appears that the high velocities opposite the intake are due to the design of the entrance region. The entrance region is possibly too small to properly redirect the vertically entering fluid into an evenly distributed flow in the primary flow direction.

• The Journal of the Korean Society for Microbiology
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• v.11 no.1
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• pp.69-78
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• 1976

There have been increasing reports of mycobacterioses in man and animals caused by "atypical" or "opportunist" mycobacteria. At the presnt, "opportunist mycobacterioses" are not generally responsive to antituberculosis drugs, and therefore, create considerable problems with regard to chemotherapy and control measures. In recent years studies have been made to isolate opportunist mycobacteria from soil, house-dusts and tap-water. It seemed quite interesting to define the extent of circumstantial presence of "opportunist" mycobacteria and nocardia in the soils of school-ground of primary schools and middle-high schools. This communication is the results of pilot study to isolate and identify "opportunist" mycobacteria and nocardia from 504 soil specimens of 72 schools in Seoul City. 1. Of a total of 59 isolates from 504 soil specimens tested, 32 strains were identified as opportunist mycobacteria and 27 strains as nocardia. 2. Isolation rates of opportunist mycobacteria by the areas(of specimen collection) were as follows: 36.4% in the southern area of Han-River, 33.3% in the central area, 22.7% in the outskirt area and 16.6% in the intermediate area. There observed no apparent difference in the isolation rates both-between the areas and between primary schools and middle-high schools. However, a significant difference was noted in the isolation rates between the places of soil sampling in a given school(P<0.05), i.e., the highest was the soil of refuge heaps(15.2%), and tap-water pole area(11.1%), the school-lavatory entrance(9.7%), the school gate entrance(5.5%), and iron-bar play ground(2.7%). The soil specimens from the center of school ground and from school building entrance yielded none of mycobacterial isolates. 3. Isolation rates of nocardia by the areas were as follows: 33.3% in the central area, 31.8% in the outskirt area, 27.3% in the southern ares of Han-River and 11.1% in the intermediate area. As in the case of mycobacteral isolates, there observed no apparent differences in the isolation rates both between the areas and between primary schools and middle-high schools, but a significant difference was noted between the places of soil sampling(P<0.05), i.e., the highest was the soil of school building entrance(15.2%), and of school gate entrance(6.9%), refuge heaps(5.5,%), iron-bar play ground(4.1%), the school-lavatory entrance(2.7%) and tap-water pole area(2.7%), respectively. The soil specimens from the center of, school ground yielded none of nocardia isolates. 4. Of the 32 strains of isolated mycobacteria. 15 strains were slow-growing mycobacteria and the remaining 17 strains belonged to the rapid growers. Of the 15 slow-growers. 4 strains were M. scrofulaceum-szulgai complex, 3 M. gordonae, 4 M. terrae-triviale complex, 2 M. avium-intracellulare-xenopi complex, and 2 unclassified schotochromogens. Of the 17 strains of rapid growers, 12 were M. diernhoferi, 2 M. fortuitum-peregrinum complex, 2 M. vaccae and one M. flavescens. 5. Of the 27 strains of nocardia isolated, 11 strains were N. transvalensis, 5 N. convoluta, 5 N. erythropolis, one N. vaccinii, one N. polychromogens-paraffinae complex and 4 untypable strains of orange-pigmented nocardia spp.

• Korean journal of applied entomology
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• v.42 no.4
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• pp.315-321
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• 2003

Larval entrance and adult emergence holes of Japanese pine sawyer (Monochamus alternatus), primary vector of pinewood nematode (Bursaphelenchus xylophilus), were measured in dead pine logs from 1999 to 2002. Their distributions within pine log were also analyzed. More numbers of entrance and emergence holes were distributed on crown than trunk part as 56.2 and 27.7 holes/m$^2$, respectively Higher proportions of entrance (27.5％) and emergence holes (22.4%) were distributed on the log with 8 to 10 cm diameter; the larger or the smaller logs had fewer holes. Surface area of entrance hole was 65.8 $\textrm{mm}^2$ and diameter of emergence holes was 7.0 mm in average. Average depth of pupal chamber was 24.8 mm from surface to the bottom of the chamber, and its volume ranged from 200 to 2.000 ㎣ Average distance between entrance and emergence holes on bark surface was 3.3 cm. Gallery length from the beginning of entrance hole to the end of emergence hole was 46.2 mm.

• Journal of Oral Medicine and Pain
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• v.23 no.1
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• pp.57-64
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• 1998

Personality characteristics were studied by means of SCL-90-R test, Behavioral problem and pain site was studied Isleep disturbance, irregular eating habit, decreased physical activity, decreased social activity, increased emotional tension) by examination sheets. This study was conducted to examine the mature and extent of psychological difference between the students who failed the college-entrance examination and freshment and to determine whether psychological distress acts as a precipitate for craniocervical pain. 96students who failed the college-entrance examination (examination-failed student) and 86 freshmen were included in this study. The obtained results were as follows : Mean T-score of SCL-90-R primary scaled and global Indies in examination-failed students were significantly higher than the freshmen group. In comparison with examination-failed student group, the prevalence of neck and shoulder pain was significantly higher than the freshmen group. When the study and control group were compared in behavioral problem the study group had not more sound sleep than the control group. The study group had more irregular eating habit than control group. The study group had the lower physical activity than control group. The study group had poor social activity than control group. There was no significant difference in emotional tension.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.202-211
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• 2000

Characteristics of the fuel injection and entrainment of the primary air of gas burner have been investigated. Primary air flow rates that entrained by gas streams play major role to control the performance of the partially premixed combustion. Pressure distributions of mixing tube assembly are studied as major parameter for increasing the primary air flow rates. Buoyancy-effect burner is proposed as one alternative to improve the pressure distribution. Buoyancy effect caused by metal ring placed around the flame holes reduces pressure of the entrance of the mixing tube and that, entrained air flow rates are increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.49-59
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• 2008

The effects of design parameters on the pellet transport rate in the ejector system which is widely used in the production processes of automotive parts were investigated experimentally. The primary nozzle geometry, the area ratio (R) of nozzle exit cross-sectional area to mixing chamber cross-sectional area and the distance (S) from primary nozzle exit to mixing chamber entrance were considered as the design parameters. The area ratios of the primary nozzle were varied from R=0.10 to R=0.25, 0.30, 0.40 and 0.55. The primary nozzle was positioned at the non-dimensional distance (S/D) of 1.30, 1.87, 2.44, 3.00 and 3.75, normalized using the mixing chamber diameter (D). The design parameters were determined to run with high efficiency by measuring the pellets transport rate. The geometry and the area ratio (R) of the primary nozzle had an effect on the pellet transport rate of the ejector system, and the area ratio of R=0.3 was carefully selected after taking the minimum fluidization velocity and transport rate of applied pellets into account. The higher pellet transport rate with the variation of the distance (S/D) was observed at S/D of 2.44.

• Journal of Power System Engineering
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• v.13 no.4
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• pp.56-61
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• 2009

In recent years, since the continuing increase in the capacity in personal computer such as the optimal performance, high quality and high resolution image, the computer system's components produce large amounts of heat during operation. This study analyzes and investigates the ability and efficiency of a cooling system inside a computer by means of central processing unit (CPU) and power supply cooling fan. This research was conducted to enhancement of efficiency of the cooling system inside the computer by making a structure which produces different air pressures in an air inflow tube. Consequently, when temperatures of the CPU and room inside computer were compared with a general personal computer, temperatures of the tested CPU, the room and the heat sink were as low as $5^{\circ}C$, $2.5^{\circ}C$ and $7^{\circ}C$ respectively. In addition to, revolution per minute (RPM) was shown as low as 250 after 1 hour operation. This research explored the possibility of enhancing the effective cooling of high-performance computer systems.

• Journal of The Korean Association For Science Education
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• v.17 no.2
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• pp.201-207
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• 1997

This study was performed to survey the achievements in problem solving by the inquiring experiment, which was done by the superior group in the traditional cocepts-centered written tests. The purpose of this study was to identify characteristics of inquiring experimental assessment by analyzing differences between concepts-centered written and inquiring experimental tests. The subjects of this study was 211 applicants. They are the superior group of the 9th grade students, and score in the top 1% of total achievements percentage in school. They also have passed the primary entrance examination. The inquiring experimental test was developed according to the curriculum in school, and is composed of 5 subcategories: problem-perception and formulating hypothesis, designing an experiment, carring out an experiment, recording data and drawing conculsion, and generalizing conculsions and communicaton. The checklists of each subcategory were made and testing methods were divided into observation and report. The major results of this study are as follows: 1. The achievements in each subcategory of inquiring experimental performance were very low in the superior group who took the concepts-centered written tests. 2. The results of factor and correlation analyses in this study confirmed the abilities measured by inquiring experimental assessment differed from abilities measured by existing tests. These results indicated that even students who achieved high in scientific knowledge, these abilities were not automatically transformed inquiry process which many other abilities were integrated into. Therefore, problem solving ability requires integrated abilities which are fostered by inquiring experimental tasks. This suggests that new instrument for assessment must be developed to measure integrating ability especially where scientifically gifted students are selected, or where entrance examinations to the science schools are administered.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.89-94
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• 2019

K1A1 tank commander's primary thermal sight is a device that enables tank commanders to detect, identify, aim and track the target by observing targets in all directions during day, night and in situations of smokescreen and fog through $360^{\circ}$ rotation independent from the gunner's primary thermal sight and stabilizing the line of sight even under the vibrations occurring when the tank is standstill and moving. The main function of this device is to detect and process visible and thermal images and deliver the final images to the tank commander. One of the core parts to that end is the observation window (daytime/thermal image window). This core part is mounted at the entrance of the optical path for observing the target and plays the role of making visible light during the daytime and infrared light during the night pass through the target and transmitting the resultant images to the internal optical system of the tank commander's primary thermal sight. Such core parts have been selected as depot maintenance items so that they are replaced by new parts instead of being recycled when they are subjected to maintenance in most cases. That is, the military budget is wasted because such parts are replaced by new parts despite that they can be recycled for maintenance. Therefore, this study proposed a mounting tool for polishing and coating observation windows (daytime and thermal image window) using planar polishing equipment and DLC (Diamond-Like Carbon) coating equipment. In addition, this study presented an amendment (proposal) of the Depot Maintenance Work Request (DMWR) already published to verify the performance of recycled products including the establishment of inspection standards for recycling processes.