• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.298-302
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• 2009

Low power Hall thruster is under development as one of the core technologies for STSAT-3. The Hall thruster has several advantages such as its simple structure, high thrust density and specific impulse etc. Development target values deduced by analyzing requirements are consumed electrical power, thrust, thrust efficiency, and specific impulse of < 300 W, > 10 mN, ~ 35%, and > 1000 s, respectively. In order to achieve the target specifications, two prototype Hall thrusters were developed and compared. To date, thrust and efficiency are 11 mN and 37% under the total power of 290 W with 0.97 mg/s Xe propellent supply.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.64-72
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• 2009

In this paper, a high efficiency 2.45 GHz rectenna with a microstrip patch antenna and a dual-mode band-pass filter in which the 2nd and 3rd harmonics are suppressed, is presented. From the experimental results, the 2.45GHz rectenna using 3rd harmonic suppressed dual-mode BPF shows the conversion efficiency of 41.6% with incident power density of 0.3 mW/cm2 and the received power of 1.66 mW. This result shows high conversion efficiency because the received power of this rectenna is lower than other rectennas to be compared with. This rectenna can be applied to the WPT (Wireless Power Transmission) field for energy harvesting. Also, it is expected to be used to provide the stand-by power for the low power devices for USN, and wireless power transfer in sensor application of MEMS devices.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.1-10
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• 2016

Despite it has been mentioned that the successful restoration in landscape level was achieved in the Young-il soil erosion control project, quantitative evaluation of restored plant communities (Alnus firma as introduced species and Pinus thunbergii as native species) was hardly founded. Light availability, litter and woody debris cover, and forest structure and composition were determined for 500 m² band-quadrat in three forest types. Abiotic factors of Q. serrata stands, as reference forest, and A. firma stands were similar but not for P. thunbergii stands. There were no significant difference on mean stem density (stems ha^-1, H = 3.6, p = 0.162), and the mean basal area of each stand had marginal significance (m² ha^-1, H = 5.7, p = 0.058) among stands as total basal area was higher with the order of A. firma (21.4 m² ha^-1), P. thunbergii (19.8 m² ha^-1) and Q. serrata (16.2 m² ha^-1). Restoration of vegetation structure was more effective in fast-growing and N-fixing A. firma, as introduced species plantation. However, result of MRPP, NMS ordination and ISPAN for herbaceous layer, not for tree and shrub species composition, indicated that restoration of ground vegetation was likely influenced highly from local environment. Propagule availability from landscape context such as connectedness to natural vegetation and management practices in restored isolated stands are available explanations for restoration effects and gaps between restored plantations and secondary oak forest.

• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.22-28
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• 1986

Densities of a large number of mixed uranyl nitrate-thorium nitrate solutions were measured with pycnometer. By the least squares analysis of the experimental result, an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions as functions of uranium concentration, thorium concentration and nitric acid normality is derived; $W=1.0-0.358\;C_u-0.4538\;C_{Th}-0.0307\;H^+$ where $W,\;C_u,\;C_{Th},\;and\;H^+$ stand for water content(g/cc), uranium concentration (g/cc), thorium concentration (g/cc), and nitric acid normality, respectively. Water contents of the mixed uranyl nitrate-thorium nitrate solutions are calculated by using the empirical formula, and compared with the values calculated by Bouly's equation in which an additional data, solution density, is required. The two results show good agreements within 2.7%.

• Journal of Korean Public Health Nursing
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• v.24 no.1
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• pp.39-48
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• 2010

Purpose: To examine the effects of a 36-week resistance training program on body composition, fitness and blood lipid profiles in the obese elderly. Method: fourteen subjects were assigned into the resistance training group. The 12-16 exercise sessions were performed for 60min with 15-25 repetitions twice per week for 36 weeks. Data were analyzed by paired t-test with SPSS version 12.0 for Windows. Results: Significant changes were evident in weight (t=5.983, p<.001), body mass index (t=5.922, p<.001), % body fat (t=3.480, p=.004), and fat free mass (t=-2.592, p=.022). Concerning exercises, no significance was noted for back scratch (t=-1.814, p=.093), but were for 2-min step (t=-3.075, p=.009), arm curl (t=-2.223, p=.045), chair stand (t=-3.671, p=.003), chair sit and reach (t=-2.508, p=.026), and 8-ft up and go (t=5.545, p<.001). No significant changes were evident in total cholesterol (t=1.189, p=.279), and total glucose (t=0.689, p=.517), while the change in high-density lipoprotein was significant (t=3.535, p=.012). Conclusion: The 36-week resistance training program enhanced body composition and physical fitness, but not blood lipid profiles in obese elderly subjects.

• Journal of Ginseng Research
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• v.7 no.2
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• pp.172-192
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• 1983

Light environment and growth of Panax ginseng In habitat and cultivation under natural shade were renewed. Grower's experiences on ginseng stand In relation to light environment were assessed. Change of shading method and grower's concepts on light requirement of ginseng plant in Korea, Manchuria and Japan was counted. Growth of wild ginseng was better under rich light. Optimum crown density index appeared to be 0.7 In natural habitat and 0.4 to 0.7 for the cultivation in forest. Change of light Intensity in forest was greatest in May and reached near to constant value (from 40% to 3% for broad leaf deciduous forest and loom 4% to 2% for pine forest). Insufficient light condition induced long and thin stem, poor flowering and seed bearing, and sequent dormancy. Relation between light and ginseng strand was not clear but light Interception with cool weather was effective. Topography and orientation of bed have been deeply considered for light environment. Panel or bark of won were used for shading in deep forest manly In Manchuria while reed blind and straw thatch were used in Korea. Kinds and number of shades material and seasonal or daily schedule have been simplified probably by labor pressure due to eulargement of plantation. Post height has been greater while width of roof, bed and ditch has changed lisle. Scientific survey in the past omitted important light control methods (complete light hardening etc) which has been practiced in specific areas. The concept and technique of light control in the past in Korea were delicate and intensive including the control of temperature and moisture. For the application of old concept in modem cultivation precise Investigation of the technique including the measurement of light, temperature and moisture is needed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.369-374
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• 1987

Relationships among root yield, planting density (PD), missing plant rate (MR), leaf area index (LAI) , leaf area per plant(LAP), root weight(RW), number of harvested root(RN) and leaf fall plant rate (LFP) were investigated by survey of white ginseng plantations in Pungi and Geumsan area. In Geumsan PD was about twice than in Pungi but yield was low with high rates of MR and LFP. Yield depended on RN in high PD cultivation while on RW in low PD. The effect of MR on yield was prominent in high PD cultivation. PD showed insignificant negative correlation with yield and no clear relation with MR. RN depended on PD and was especially limited by MR, Yield depended on LAI at harvest time and especially at maximum growth time. LAI was not different between high and low PD area but depended only on RN in high PD and only on LAP in low PD area, and limited by MR in both PD. LAP depended highly on RW and this fact seems to be the very reason that LAI could not increase with the increase of PD. All fields showed the suboptimum LAI.

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.119-130
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• 2002

The nonlinear finite element program has been developed to analyze the design performance of an artificial hip prosthesis and long term behavior of a treated femur with stems made of composite material after cementless total hip arthroplasty(THA). The authors developed the three dimentional FEM models of femoral bone with designed composite stem which was taken with elliptic cross section of 816 brick elements under hip contact load and muscle farce in simulating single leg stand. Using the program, density changes, stress distributions and micromotions of the material femoral bone were evaluated by changing fiber orientation of stems for selected manufacturing method such as plate cut and bend mold. The results showed that the composite materials such as AS4/PEEK and T300/976 gave less bone resorption than the metallic material such as cobalt chrome alloy, titanium alloy and stainless steal. It was found that increasing the long term stability of the prosthesis in the femur could be obtained by selecting the appropriate ply orientation and stacking sequence of composite.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.2
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• pp.69-84
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• 2007

Producing printing plate is essential progress to do offset printing. In this Film-less period, the more PS plate becomes extinct, the more the age of the Plate-Making of Exposure declines the place to stand. To do offset printing, the CTP (Computer to Plate) is taking a place of PS plate that covers speed, quality and economical problems. The biggest advantage of using CTP is that laser directly goes to the plate, thus there are no dust from the Plate-Making of Exposure. It is also theoretically able to print $200lpi{\sim}300lpi$ as well as print 1751pi, because it has over 2400dpi resolution. The high quality printing could be available inside of the country, if printing machine keeps the optimum condition in offset printing. The CTP has many advantages, however there is a difficulty for the operators to preserve the equipment. The actual circumstance is that they cannot make a decision about how many dots need to be generated, and also it is necessary to know how to establish the setup at RIP on CTP to make the optimum condition output. If offset printing machine keeps the optimum condition, it would be able to print up to high quality printing however it is hard to comment what is the optimum condition for the printing machine. Anyone could say easy subjectively that machine is in the optimum condition, however it is objectively hard to estimate by number. In this research GATF / Plate Test target used to analyze the image and to make numerical value of the optimum condition of the CTP. It also used GATF / The sheep fed test printing 5.0 to know the density of the color representation, dot gain and gray balance for the optimum condition of the print machine. The purpose of this research is to represent the ISO 12647-2 which is the international standard with domestic printing equipments.

• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.737-744
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• 2004

In this study, to evaluate the effect of forest vegetation on the long-term water balance in a watershed, semi-distributed and physically based parameter model, SWAT was applied to the Bocheong watershed, and the variation of hydrological components such as evapotranspiration, surface flow, lateral flow, base flow, and total runoff was investigated with coniferous and deciduous forests, respectively. First, SWAT model was modified to simulate the actual plant growth pattern of coniferous trees which have the uniform value of leaf area index all the seasons of the year. The modified model was applied to the watershed that is assumed to have only one land cover in the whole watershed, and the variation of the water balance components was investigated for each land cover. It was found that coniferous forest affected the increase in evapotranspiration and decrease in runoff more than deciduous forest. However, the age and the density of stand, the location, and soil characteristics and meteorological conditions including the tree species should be also considered to examine the effect more quantitatively and to reduce the uncertainties in simulated output from the hydrological model.