• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.22-30
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• 2010

KARI had integrated and tested GEO satellite in cooperation with Astrium Inc., France. In the middle of integration and test, It was necessary to check GEO satellite SA(solar array) status and require electrical interface verification with bus. SA of GEO satellite have different mechanical characteristics in comparison with those of LEO satellite which was tested in KARI. LEO SA has been deployed by simple mechanical hinge system but GEO SA has been done by more complicated method. so in this paper, we designed the test configuration and analyzed the test result of solar array electrical integration of GEO satellite.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.31-36
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• 2009

There have been many solar tracking systems developed for the high accuracy in solar tracking. One of the key components of any motion control system is software. LabVIEW offers an ideal combination of flexibility, ease-of-use and well-integration with other I/O pieces for developing solar tracking system. Real-time solar positions which vary with GPS's data are used simultaneously to control the solar tracker by a chain of operating modes between the open and closed loops. This paper introduces a step by step procedure for the fabrication and performance assessment of a precision solar tracking system. The system developed in this study consists of motion controllers, motor drives, step-motors, feedback devices and application. CRD sensors are applied for the solar tracking system which play a primary role in poor conditions for tracking due to a gear backlash and a strong wind. Mini-dish was used as a concentrator for collecting sun light. The solar position data, in terms of azimuth and elevation, sunrise and sunset times was compared with those of KASI(Korea Astronomy & Space Science Institute). The results presented in this paper demonstrate the accuracy of the present system in solar tracking and utilization.

• The Journal of Korean Society for School & Community Health Education
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• v.14 no.2
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• pp.47-57
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• 2013

Backgrounds: According to a high interest in health these days, a bicycle is being highlighted as a means of leisure activity and auxiliary transportation means. Along with an increase in this interest, there is tendency that even the width of bicycle utilization gets diverse and that bicycle accident is also rapidly growing. Purpose: The purpose of this study was to suggest a prevention measure available for reducing occurrence of bicycle accidents by analyzing the Epidemiological characteristics according to age and injury severity in bicycle-injured patients. Methods: This study analyzed 115 materials suitable for this study by examining a medical record of patients, who received the hospitalized treatment owing to bicycle accident from January 1, 2011 to December 31 at one general hospital in S city. Results: The male-and-female ratio of bicycle-injured patients stood at about 7:3. The average age was 38.14(${\pm}21.59$) years old. The largest injury happened in 40-59 years old(31.3%). The averagely hospitalized period was 17.33(${\pm}18.12$) days. Injury severity was the ratio of 2:8 in a mild case versus a serious case. As for drinking and smoking characteristics according to age, the injury occurred the most in between 40 and 59 years old for people with drinking and smoking and in under 19 years for people without drinking and smoking. According to injury severity, the ratio of serious case got higher in the higher age. This was indicated(${\chi}^2$=15.675, p=0.001) to be statistically significant. Conclusion: In this study, a bicycle accident was indicated to have high injury risk in young children, adolescents, and old-age group. Prevention measure and publicity are demanded for reducing injury occurrence such as the prevention education for bicycle accident and wearing protective gear focusing on the ages of corresponding to groups with risk of injury occurrence. In addition, the security of safe movement route is necessarily demanded in order to increase application level as an auxiliary transportation means.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.493-503
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• 2015

Species composition and bycatch rate of the catches by dredge with bycatch reduction device to reduce bycatch were estimated around Yeongil Bay, Korea at June, 2015. Total catches were collected 31 species as Chordata 10 species, mollusca 8 species, arthropoda 6 species, echinodermata 5 species, sipunculida 1 species, annelida 1 species during the experiment at the Yeongil Bay. The dominant species were Scapharca broughtonii, Callithaca adamsi, and Atrina pectinata and they reached 79.9% of the total catch. The catch rate of Scapharca broughtonii and Callithaca adamsi was 69.6% and 10.4% respectively. The rate of bycatch was 20.1%, consisted with Echinodemata 13.0%, Chordata 3.6%. The catch of ordinary dredge was 27 species 1,307 number 85,052g and that of dredge with escapement device was 21 species 1,690 number 91,648g. In conclusion, the dredge gear with bycatch reduction device has higher catch rate of target species and lower bycatch rate to non-target species than ordinary one.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.1
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• pp.48-55
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• 2016

The species composition and distribution of catches by dredge gear in the Yeongil Bay, Korea were investigated on a seasonal basis from February to November, 2015. Total catches consisted of 44 species and 35 families. They were 13 species of fish, 10 species of crustacea, 5 species of echinodermata, 5 species of gastropoda, 4 species of cephalopoda and 3 species of bivalvia. Major catch species was shellfish and had seasonal variations in catch. In spring and winter, the catch of ark shell (Scapharca broughtonii) was increased. Adversely, the catch of admas venus clam (Callithaca adamsi) increased in sunmmer and autumn. Species diversity indices was high as the value of 1.99 in spring, and low to the value of 0.34 in summer. In addition, multi dimentional scaling (MDS) indices also was high in spring as the value of 1.99. In summer, the index was low as the value of 0.34. Similarity analysis based on species data was transformed by fourth root. With the result of cluster analysis and MDS analysis, species was divided into two groups. The first group as Group A consists of winter and spring species and another was Group B made of species in summer and winter.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.189-194
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• 2005

The evaporation heat transfer and pressure drop of $CO_2$ in a small diameter tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator(test section). The test section was made of a horizontal stainless steel tube with the inner diameter of 4.57 mm, and length of 4 m. The experiments were conducted at mass flux of 200 to 700 $kg/m^2s$, saturation temperature of $0^{\circ}C$ to $20^{\circ}C$, and heat flux of 10 to 20 $kW/m^2$ . The test results showed the evaporation heat transfer of $CO_2$ has great effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation pressure drop of C02 are highly dependent on the mass flux. In comparison with test results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient and pressure drop of $CO_2$, therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient and friction pressure drop of $CO_2$ in a horizontal tube.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.262-267
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• 2005

The evaporation heat transfer coefficient of $CO_2$ in a horizontal round tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator(test section). The test section was made of a horizontal stainless steel tube with the inner diameter of 7.75 mm, and length of 5 m. The experiments were conducted at mass flux of 200 to 500 $kg/m^2s$, saturation temperature of $-5^{\circ}C$ to $5^{\circ}C$, and heat flux of 10 to 40 $kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has great effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. In comparison with teat results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient of $CO_2$, therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

• Korean Journal of Agricultural Science
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• v.40 no.3
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• pp.237-241
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• 2013

This study started to export an orchard tractor to Europe under the situations that R&D activities for orchard tractor were marginal and even it was not produced. The R&D for orchard tractor has been progressed and the most of it is accomplishing the goal. In this study, the durability of clutch friction part was tested for F/R clutch and moment of inertia of PTO clutch, and it was compared with the design criteria of transmission of tractor. According to the results of inertia test of F/R clutch, hydraulic pressures of clutch satisfied $1,961.33{\pm}196.13kPa$ of design criteria, and the variations of torque for forward and reverse operation were relatively constant. Therefore, it was found that the durability of clutch friction part was stable and reliable. Test results showed that the main hydraulic pressures were maintained $1,961.33{\pm}196.13kPa$ during the tests of moment of inertia of PTO clutch, and when it was operated, the hydraulic pressures were reached $1,961.33{\pm}196.13kPa$. Therefore, it was found that the hydraulic pressures of PTO satisfied the design criteria. By the results that the time of the hydraulic pressures of PTO reaching main hydraulic pressure, and that of torque values restoring to the original was same as the time of the first gear of PTO reaching the maximum rotational speed, it was found that PTO could transfer power to attachments as it was designed.

• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.221-232
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• 2012

We analyzed the manufacturing procedure, specifications, repair history, and details of celestial movements of the water-hammering type $Honsang$ (celestial globe). Results from our study on the remaining $Honsangs$ in China and Japan and on the reconstruction models in Korea were applied to our conceptual design of the water-hammering type $Honsang$. A $Honui$ (armillary sphere) and $Honsang$ using the water-hammering method were manufactured in $Joseon$ in 1435 (the 17th year of King $Sejong$). $Jang$ $Yeong-Sil$ developed the $Honsang$ system based on the water-operation method of $Shui$ $y{\ddot{u}}n$ $i$ $hsiang$ $t'ai$ in China. Water-operation means driving water wheels using a water flow. The most important factor in this type of operation is the precision of the water clock and the control of the water wheel movement. The water-hammering type $Honsang$ in $Joseon$ probably adopted the $Cheonhyeong$ (天衡; oriental escapement device) system of $Shui$ $y{\ddot{u}}n$ $i$ $hsiang$ $t'ai$ in China and the overflow mechanism of $Jagyeongnu$ (striking clepsydra) in $Joseon$, etc. In addition to the $Cheonryun$ system, more gear instruments were needed to stage the rotation of the $Honsang$ globe and the sun's movement. In this study, the water-hammering mechanism is analyzed in the structure of a water clock, a water wheel, the $Cheonhyeong$ system, and the $Giryun$ system, as an organically working operation mechanism. We expect that this study will serve as an essential basis for studies on $Heumgyeonggaknu$, the water-operating astronomical clock, and other astronomical clocks in the middle and latter parts of the $Joseon$ dynasty.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.167-174
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• 2005

The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500kg/m^2s$, saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greater effect on nucleate boiling than convective boiling. The evaporation heat transfer coefficient of $CO_2$ is highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the correlation of Jung et al. But the existing correlations failed to predict the evaporation heat transfer coefficient of $CO_2$. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.