• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.71-75
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• 2009

30톤급 액체로켓엔진 재생냉각 연소기에서 넓은 영역에서의 연소기 작동성 및 연소성능 등을 확인하기 위한 저압 및 설계/탈설계점 연소시험 결과에 대해 기술하였다. 연소기의 연소압력은 60 bar, 추진제 유량은 약 89 kg/s 그리고 노즐 팽창비는 12이다. 연소특성속도에 대한 압력의 영향은 혼합비에 따라 크게 나타났다. 연소기의 비추력은 혼합비에 크게 영향을 받지 않았고 압력에 비례함을 알 수 있었다. 본 결과는 향후 대형 연소기에서 저압 연소시험의 가능성을 제시할 뿐만 아니라 대형 연소기의 고압 연소압력에서의 연소성능을 예측하는 기본 데이터로 활용될 수 있을 것이다.

• 농업과학연구
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• 제37권3호
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• pp.435-449
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• 2010

Soils in the sloping uplands in Korea are subject to intensive land use with high input of agrochemicals and are vulnerable to soil erosion. Development of the environmentally sound land management strategy is essential for a sustainable production system in the sloping upland. This report addresses the status of upland agriculture and the best management practices for the uplands toward the sustainable agriculture. More than 60% of Korean lands are forest and only 21% are cultivating paddy and upland. Uplands are about 7% of the total lands and about 62% of the uplands are in the slopes higher than 7%. Due to the site-specificity of the upland, many managerial and environmental problems are occurring, such as severe erosion, shallow surface soils with rocky fragments, and loadings of non-point source (NPS) contaminants into the watershed. Based on the field trials, most of the sloping uplands were classified as Suitability Class III-V and the major limiting factor was slope and rock fragments. Due to this, soils were over-applied with N fertilizer, even though N rate was the recommendation. This resulted in decreases in yield, degradation of soil quality and increases in N loading to the leachate. Various case studies drew management practices toward sustainable production systems. The suggested BMP on the managerial, vegetative, and structural options were to practice buffer strips along the edges of fields and streams, winter cover crop, contour and mulching farming, detention weir, diversion drains, grassed waterway, and slope arrangement. With these options, conservation effects such as reductions in raindrop impact, flow velocity, runoff and sediment loss, and rill and gully erosion were observed. The proper management practice is a key element of the conservation of the soil and water in the sloping upland.

• 한국환경과학회지
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• 제11권8호
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• pp.819-827
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• 2002

Laboratory scale experiments were conducted to evaluate the performance of a biofilter for eliminating dimethyl sulfide(DMS). A commercial compost/pine bark nugget mixture served as the biofilter material for the experiments. The gas flow rate and DMS concentration entering the filter were varied to study their effect on the biofilter efficiency. The operating parameters, such as the residence time, inlet concentration, pH, water content, and temperature, were all monitored throughout the filter operation. The kinetic dependence of the DMS removal along the column length was also studied to obtain a quantitative description of the DMS elimination. High DMS removal efficiencies(>95％) were obtained using the compost filter material seeded with activated sludge. DMS pollutant loading rates of up to 5.2 and 5.5 g-DMS/m$^3$/hr were effectively handled by the upflow and downflow biofilter columns, respectively. The macrokinetics of the DMS removal were found to be fractional-order diffusion-limited over the 9 to 25 ppm range of inlet concentrations tested. The upflow column had an average macrokinetic coefficient(K$\_$f/) of 0.0789 $\pm$ 0.0178 ppm$\^$$\sfrac{1}{2}$//sec, while the downflow column had an average coefficient of 0.0935 $\pm$ 0.0200 ppm$\^$$\sfrac{1}{2}$//sec. Shorter residence times resulted in a lower mass transfer of the pollutant from the gas phase to the aqueous liquid phase, thereby decreasing the efficiency.

• 대한족부족관절학회지
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• 제6권1호
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• pp.21-27
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• 2002

Pressure sores are an ulceration and necrosis of the skin and underlying tissue usually occur after prolonged or repeated pressure by interruption of blood flow from the small. vessels to the skin and deep tissue. The management of pressure sores is mostly difficult and requires prolonged hospitalization or repeated surgical interventions with a high recurrence rate. In this article we reviewed 14 cases of National Pressure Ulcer Advisory Pannel staging III, IV over the lateral malleolar area of the ankle in 2 years period from January 1999 to October 2001. The pressure over lateral malleolar area was mainly due to unique Korean sitting position with cross legs at flexed hips and knees or supine position of patient with external rotation of low extremity. Male to female ratio was 11: 3 and ages were between 36 and 83 (mean age: 67.1 years). Associated diseases were DM(7 cases), Hemiparesis caused by CVA(2 cases), Liver cirrhosis(2 cases), disarticulation of opposite hip due to squamous cell ca.(1 case), Intertrochanteric Fx.(1 case). Wound cultures reported Staphylococus, Pseudomonas and others. Abnormally elevated ESR and CRP were seen in 6 cases. Operative treatments were irrigation and debridement, direct closure with gravity drainage and skin grafting. The most important aspect of pressure sore treatment is pressure relief of the lateral malleolar area. Pressure-relieving Cast or Brace was helpful for local management and preventing recurrence.

• 한국관광식음료학회지:관광식음료경영연구
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• 제17권1호
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• pp.41-67
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• 2006

The study is aimed to analyze the influence of FTA(Free Trade Agreement) between Korea and Japan on tourism and to suggest ways to increase tourists exchange between them by considering countermeasures of Korea's tourism based on the analysis and deriving political significance. The results of the study showed that the expected effects of FTA between Korea and Japan on tourism would overall be positive. There would be increases in employment and a higher rate of foreign-exchange earning, which plays a critical role in the cash flow. Therefore the government is required to prepare for several political measures as follows. First, ways to promote investment in tourism have to be established in a systematic way for FTA. Second, restructuring of tourism has to be considered seriously for tourism to be a high value-added industry after FTA. Third, the tourism information industry needs to be included in the tourism promotion act to promote e-tourism using information technology. In addition to this, an expansive cluster strategy needs to be developed, which relates tourism to other industries like culture and movies and to find ways to re-locate and re-educate manpower currently engaged in the tourism industry. Though the study investigated the influence of FTA on tourism through a practical analysis, it was restricted only to Korea. So the influence of FTA between Korea and Japan on the tourism of Japan should be included in further study. Furthermore, in subsequent studies the CGE(Computable General Equilibrium) model will be applied for objective analysis of the effects. Or measuring the ripple effect with multinational inter-industry relation table will be made for the study to make practical contributions to the development of government policy.

• 연구논문집
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• 통권27호
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• pp.87-99
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• 1997

Present paper describes on/off design performance of a 50KW turbogenerator gas turbine engine for hybrid vehicle application. For optimum design point selection, relevant parameter study is carried out. The turbogenerator gas turbine engine for a hybrid vehicle is expected to be designed for maximum fuel economy, ultra low emissions, and very low cost. Compressor, combustor, turbine, and permanent-magnet generator will be mounted on a single high speed (82,000 rpm) shaft that will be supported on air bearings. As the generator is built into the shaft, gearbox and other moving parts become unnecessary and thus will increase the system's reliability and reduce the manufacturing cost. The engine has a radial compressor and turbine with design point pressure ratio of 4.0. This pressure ratio was set based on calculation of specific fuel consumption and specific power variation with pressure ratio. For the given turbine inlet temperature, a rather conservative value of $1100^\circK$ was selected. Designed mass flow rate was 0.5 kg/sec. Parametric study of the cycle indicates that specific work and efficiency increase at a given pressure ratio and turbine inlet temperature. Off design analysis shows that the gas turbine system reaches self operating condition at N/$N_{DP}$ = 0.53. Bleeding air for turbine stator cooling is omitted considering low TIT and for a simple geometric structure. Various engine performance simulations including, ambient temperature influence, surging at part load condition. Transient analysis were performed to secure the optimum engine operating characteristics. Surge margin throughout the performance analysis were maintained to be over 80% approximately. Validation of present results are yet to be seen as the performance tests are scheduled by the end of 1998 for comparison.

• 한국한의학연구원논문집
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• 제15권1호
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• pp.85-89
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• 2009

The aim of this study was to study the quantitative analysis of glycyrrhizic acid in Glycyrrhizae Radix extract fermented with Paecilomyces japonica, Ganoderma lucidum, honey or Nuruk. The amounts of dry on loss were measured and the quantitative analysis of glycyrrhizic acid was performed by high performance liquid chromatographic (HPLC). HPLC method was performed on C18 column ($250\;mm\;{\times}\;4.6\;mm$, $5\;{\mu}m$, RS tech) using gradient solvent mixtures of water-acetonitrile with photodiode array detector (254 nm). The flow rate was $1.0\;m{\ell}/min$. Retention time of glycyrrhizic acid was about 23.96 min and linearity of calibration was $R^2$=0.9998. Contents of glycyrrhizic acid in Glycyrrhizae Radix extract (control) was $5.048\;{\pm}\;0.14$; Contents of glycyrrhizic acid in Glycyrrhizae Radix extract fermented with Paecilomyces japonica (SDT) was $1.975\;{\pm}\;0.07$; Contents of glycyrrhizic acid in Glycyrrhizae Radix extract fermented with Ganoderma lucidum (SYT) was $2.676 \;{\pm}\;0.07$; Contents of glycyrrhizic acid in Glycyrrhizae Radix extract fermented with honey (SST) was $5.191\;{\pm}\;0.06$; Contents of glycyrrhizic acid in Glycyrrhizae Radix extract fermented with Nuruk (SNT) was $5.305\;{\pm}\;0.34$, respectively. Contents of glycyrrhizic acid in SDT and SYT were decreased but that in SST and SNT was increased when compared to control.

• 한국세라믹학회지
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• 제41권2호
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• pp.118-124
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• 2004

탄소환원질화법에 의해 합성된 질화알루미늄의 물성은 출발물질의 종류, 액상$.$기상 반응물질의 양, 분위기 그리고 합성온도에 따라서 많은 차이를 나타내었다 질화알루미늄 합성을 위하여 Al원으로는 $\alpha$-A1$_2$O$_3$를 사용하였고 환원제로는 카본 블랙을 사용하였으며, 기상반응을 유도하기 위하여 AlF$_3$를 사용하여 고순도 질소분위기에서 실험을 행하였다. 또한 액상반응 시 미세구조상의 변화를 확인하기 위하여 금속 알루미늄을 첨가하여 실험을 행하였다. 질화알루미늄이 생성과 침상형 휘스커상의 형상은 1$600^{\circ}C$의 온도에서 가장 잘 나타났으며 열처리 온도의 상승은 오히려 휘스커상의 형성을 방해하고 있음을 보여주었다. 침상형 휘스커의 합성에 가장 큰 영향을 주는 것은 기상반응을 일으키는 AlF$_3$ 첨가이며, AlF$_3$의 첨가량이 증가함에 따라 침상형 휘스커상을 확인하였다. 액상반응을 위한 금속 알루미늄 첨가는 전체의 15wt%까지는 침상형 휘스커가 증가하고 있음을 나타내었으나 l5wt% 이상으로 첨가하는 경우 오히려 휘스커가 감소하는 것으로 나타났다.

• 한국가스학회지
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• 제2권4호
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• pp.47-52
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• 1998

수냉식 흡수식 냉동기에 주로 사용되고 있는 LiBr/water 흡수용액을 대체할 수 있는 신흡수 용액으로 제안된 흡수용액중 4성분계 흡수용액($LiBr+LiNO_3+LiC1+H_2O$)의 수증기 흡수성능을 수직관 흡수기를 사용하여 시험하였다. 시험변수로는 입구농도, 입구온도, 냉각수 입구온도, 용액유량을 변경하였다. 수증기 흡수특성 시험 결과 4성분계 용액이 LiBr/water용액보다 $2\%$ 높은 농도에서 대둥한 흡수력을 가짐을 알 수 있었다. 그러나 4성분계 흡수용액이 LiBr/water용액보다 $3\%$정도 용해도가 높으므로 실제 흡수식 냉동기에 적용시 LiBr용액보다 우수한 흡수능력을 가질 수 있어 소형, 공냉형 흡수식 냉동기에 적용이 가능하다.

• 대한전자공학회논문지
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• 제26권6호
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• pp.48-56
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• 1989

밀착형 1차원 영상감지소자로서 팩시밀리에 사용될 광도전막을 사일랜듸 글로방전 분해법으로 제작하였다. 우선 rf전력, 사일랜유량, 분위기 가스압, $H_2/SiH_4$비 및 기판온도의 증착조건에 따른 단층광전도막의 전기적 및 광학적특성을 조사하였다. 이 단층구조 영상감지막은 광전감도 0.85와 100lux 조도하에서 $I_{ph}/I_d=100$을 나타내었다. 그러나 이러한 단층박막은 양 전극으로 부터의 캐리어주입으로 인해 큰 암전류도 0.2nA 이하를 나타내었다. 또한 다층막은 단층막에 비해 단파장 가시광영역이 보상되어 팩시밀리용 1차원 영상감지소자에 사용될 만한 결과를 나타내었다.