• 한국항공우주학회지
• /
• 제38권1호
• /
• pp.12-21
• /
• 2010

본 논문에서는 부분적인 지면효과 하에서의 단일로터 블레이드에 대한 제자리 비행 성능 특성을 확인하였다. 이를 위해 소형 로터 블레이드 회전 시험장치와 이동식 바닥면을 이용하여 고정된 회전속도에서 콜렉티브 피치각을 변화시키면서 추력과 토크를 측정하였다. 로터면과 지면이 겹치는 거리를 d, 로터의 직경을 D라 하면 지면효과가 없을 때부터 d/D가 0.25일 때까지는 지면효과가 로터의 성능에 거의 영향을 미치지 않는 것으로 확인되었다. 로터 깃의 개수가 4개일 때 지면 효과의 영향을 더 크게 받아 2개일 때보다 추력이 증가하고 동력이 감소하였다. 또한 피치각이 작을수록 지면효과로 인하여 추력이 증가하는 경향을 보였다. 이와 같은 실험 결과를 바탕으로 로터 깃의 개수와 부분적인 지면 효과를 고려한 새로운 경험식을 도출하였다.

• 설비공학논문집
• /
• 제25권8호
• /
• pp.443-449
• /
• 2013

The purpose of this study is to propose an enhanced variable-speed control method of ground-water circulation pumps using inlet and outlet ground-water temperature difference and analyze its effect for the ground source multi-heat pump system installed in a single-family house. As a result, it has shown to significantly reduce the electricity use of ground-water circulation pump and improve overall system Coefficient of Performance (COP) due to the proposed variable-speed control under partial load conditions after oversized and inefficient single-speed pump retrofit.

• 대한임상전기생리학회지
• /
• 제10권1호
• /
• pp.15-22
• /
• 2012

Purpose : We investigated the effects of the combined use of FES and over ground walking with partial body-weight support (PBWS) on walking function and balance control in people with chronic strokes. Methods : Twenty-seven people who were ambulatory after chronic strokes were evaluated. The exercise's intervention consisted of the combined use of FES and over ground walking with PBWS and general exercise groups. The FES + PBWS group and general exercise group consisted on a-20-minute session per day, 3 times a week during a 4 week period. The evaluation was carried out before, after, and two weeks after the exercise intervention. Outcome measures were a 6 Minute Walk Test, 6-Meter walk Test, Timed Up and Go Test, and a Balance Test, measured before and after the exercise interventions at a-2 week follow up. Results : The endurance was significantly increased in both the FES+PBWS group and general exercise group (p<0.05). Significant increase on the gait velocity was observed in both the FES+PBWS group and general exercise group (p<0.05). The TUG was significantly different in both the FES + PBWS group and general exercise group (p<0.05). However there were no differences in both the between-group & interaction. The stability index was significantly different in both the FES + PBWS group and general exercise group (p<0.05). Conclusion : In conclusion, the combined use of FES and over ground walking with PBWS led to an improvement in walking function and balance control. Thus, it is possible to combine the use of FES and over ground walking with PBWS for physical therapy intervention to improve walking function and balance control. It is suggested to apply this intervention in the clinical field.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 C
• /
• pp.1320-1325
• /
• 1995

For hydrogen-cooled large turbine generators, partial discharges in ground wall insulations are suppressed by high hydrogen pressure. The first goal of the experiment is to investigate the effect of hydrogen pressure on partial discharge activity and aging rate in turbine generator winding insulations. A series of tests have been performed on two groups of the accelerated aging experiments. The first group of stator windings was aged under hydrogen pressure of 4 atm while the second group of stator windings was aged under air atmosphere. The stator windings aged under air atmosphere suffer from larger partial discharge magnitude with larger voids at high electrical stress than those under hydrogen pressure. The second goal of the experiment is to evaluate the validity of on-line measurement technique which is normally measured under hydrogen environment. The test results show that further experiments are needed to apply the on-line scheme to turbine generator being under high hydrogen pressure.

• 화약ㆍ발파
• /
• 제36권4호
• /
• pp.16-25
• /
• 2018

터널 굴착시 지반진동을 감소시키기 위해 굴착면에 부분적인 자유면을 형성하고 제어발파를 수행하는 자유면 발파공법이 적용되어 왔다. 본 연구에서는 다이어몬드 와이어 쏘를 이용하여 인공절리를 심발부에 형성하고, 심발부 발파 시 발생되는 지반진동을 비교함으로써 인공절리에 의한 지반진동 감소를 평가하였다. 해석 결과, 일반 심발발파보다 인공절리 심발발파에서 지반진동이 감소하였으며, 수직 인공절리 심발발파보다 수평 인공절리 심발발파에서의 지반진동 감소 효과가 더 크게 평가되었다.

• 한국환경과학회지
• /
• 제7권3호
• /
• pp.349-360
• /
• 1998

Effects of uniform flow on a two-dimensional mesoscale horizontal convection were investigated by using the vorticity and thermodynamic equations. For thins purpose, We simulated properties of a thermal convection m a stably stratified Boussinesq flued caused by partial heating at the center of a lower boundary If we don't consider effects of the uniform flow, the convection takes the form of aidsymmetrlc with respect to the z-alds. But when uniform flow Is strong, velocity field and temperature field consist of a sin91e cell structure which spreads upstream side of the partial heating area. The flow pattern for strong uniform flows takes the form of positive temperatue near the ground and negative temperature perturbation soft over the partial heating area, and downward motion directly over the upwind portion of the partial heating area and upward motion on the downstream side. The downstream edge of the upstream cell Is shifted in the downstream direction with the Increase of uniform flow almost linearly.

• 항공우주기술
• /
• 제9권1호
• /
• pp.84-92
• /
• 2010

통신해양기상위성의 명칭인 천리안위성 발사를 앞두고 위성운용을 위한 지상시스템의 검증이 실제 위성과 위성시뮬레이터 등을 이용하여 수행되었다. 본 논문에서 특히 시뮬레이터가 적용된 지상시스템 시험 부분을 중점적으로 분석하여 시뮬레이터의 활용시간, 활용범위, 활용비중 등을 기술한다. 아울러 시스템 검증을 위한 시뮬레이터의 적용 경험을 바탕으로 시뮬레이터의 효과를 설명하고 한계점과 개선방향을 제시한다.

• 동아시아식생활학회지
• /
• 제4권3호
• /
• pp.123-133
• /
• 1994

The ground pork patties were made to add two level of sodium chloride(2.5%, 3.0%) and replace part(50%) of the sodium chloride(NaCl) with either potassium chloride(KCl), magnesium chloride(MgCl2) or calcium chloride(CaCl2). These samples were analyzed for their chemical composition, VBN value, TBA value, microbial counts, and cooking loss. The ground pork with NaCl 2.5% was more desirable in saltness than the ground pork with NaCl 3.0%. Replacing 50% of the sodium chloride with potassium chloride was more desirable to flavor, color, juiciness, and overall acceptability than replacing 50% of the sodium chloride with either magnesium chloride or calcium chloride. The ground pork with NaCl 2.5% or NaCl 1.25% ＋KCI 1.60% had higher pH value than the ground pork with NaCl 1.25% ＋MgCl2 0.67% or NaCl 1.25% ＋CaCl2 0.79%. The ground pork with the ground pork with NaCl 2.5% had lower VBN value than the ground pork with either NaCl 1.25%＋KCI 1.60%, NaCl 1.25% ＋ MgCl2 0.67%, or NaCl 1.25% ＋CaCl2 0.79%. The ground pork with NaCl 1.25% ＋ CaCl2 0.67% had higher increase in total colony count than the ground pork with NaCl 2.5% or NaCl 1.25% ＋ CaCl2 0.79%. Cooking loss of ground pork with NaCl 2.5% was lowest and cooking loss of ground pork with NaCl 1.25% ＋ KCl 1.60% was highest. Potassium chloride would not be a substitute for sodium chloride in cooking loss and total colony count but potassium chloride more closely approximated the sensory properties of sodium chloride than either magnesium chloride or calcium chloride.

• Computers and Concrete
• /
• 제13권1호
• /
• pp.17-30
• /
• 2014

This research presents the effect of various ground pozzolanic materials in blended cement concrete on the strength and chloride penetration resistance. An experimental investigation dealing with concrete incorporating ground fly ash (GFA), ground bottom ash (GBA) and ground rice husk ash (GRHA). The concretes were mixed by replacing each pozzolan to Ordinary Portland cement at levels of 0%, 10%, 20% and 40% by weight of binder. Three different water to cement ratios (0.35, 0.48 and 0.62) were used and type F superplasticizer was added to keep the required slump. Compressive strength and chloride permeability were determined at the ages of 28, 60, and 90 days. Furthermore, using this experimental database, linear and nonlinear multiple regression techniques were developed to construct a mathematical model of chloride permeability in concretes. Experimental results indicated that the incorporation of GFA, GBA and GRHA as a partial cement replacement significantly improved compressive strength and chloride penetration resistance. The chloride penetration of blended concrete continuously decreases with an increase in pozzolan content up to 40% of cement replacement and yields the highest reduction in the chloride permeability. Compressive strength of concretes incorporating with these pozzolans was obviously higher than those of the control concretes at all ages. In addition, the nonlinear technique gives a higher degree of accuracy than the linear regression based on statistical parameters and provides fairly reasonable absolute fraction of variance ($R^2$) of 0.974 and 0.960 for the charge passed and chloride penetration depth, respectively.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 춘계 학술발표회
• /
• pp.1068-1075
• /
• 2009

The Soil-nailing installed to the slope or the vertical excavation surface shows reinforce effect using frictional resistance between ground and grout. This friction is showed the more the shape of grout is rough, the more efficient.. This study is about the characteristic behavior of Soil-nailing has partial extension grout made artificially control. In this study, we refer to the new boring machine that can make partially extended grout and perform 3D analysis between of the partial extended grout and the general grout of a cylinder shape using the finite element method for comparing.