• 한국도로학회논문집
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• 제6권1호
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• pp.47-56
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• 2004

신 구 콘크리트의 부착강도 시험시 두 재료의 계면에서 파괴가 유도되어 순수한 부착강도를 측정할 수 있도록 계면에 원형의 비부착면을 삽입하여 직접인발시험에 의해 부착강도를 측정하는 실험방법을 제시하였다. 먼저, 새로 제안한 실험방법에 의해 계면에서 응력이 집중되는 정도를 파악하기 위해 유한요소해석을 수행하여 두 재료의 탄성계수비 및 비부착면의 면적 (균열률)에 따른 계면에서의 파괴에너지를 산정하였으며, 부재의 크기 및 하중에 대한 보정을 감안하여 무차원함수로 환산하였다. 그리고 본 연구에서 제시된 부착강도 시험방법의 신뢰성을 입증하기 위해, 3가지 크기의 원형 비부착면(균열률 0.2, 0.4. 0.6)이 삽입된 신 구 콘크리트 복합시편(유황 폴리머 콘크리트+보통 콘크리트)을 사용하여 부착강도를 측정하였고 앞서 전개된 무차원함수로부터 계면 파괴에너지를 역산하였다. 시험결과, 모든 시편이 계면에서 파괴가 유도되었다. 또한 실험 데이터 및 해석결과를 분석하여 균열률이 0.4$\sim$0.6인 경우에 부착강도의 오차가 가장 적게 발생될 수 있음을 파악하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.214-214
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• 2003

During a model test of Hutton TLP, a "ringing" response was first observed about 20 years ago. This phenomenon is a resonant build up over the time of wave period and this burst-like motion can cause the extreme load on the TLP tether. It is often detected in the large and steep irregular waves but the generation mechanism leading to the "ringing" is not yet well understood. According to the research since then, the higher order harmonic components may account for the "ringing" on the floating offshore structures. The main purpose of the present research is, thus, to measure the higher harmonic forces exerted on a vertical truncated circular column and to compare them with available data. A vertical truncated cylinder with a diameter of 3.5inch and a draft of 10.5inch is used as a test structure, which is a scaled model of ISSC TLP column. The cylinder is installed at a distance of 45ft from the wave maker in order to avoid parasitic waves created in the wave flap. Attached to the upper part of the cylinder are two force gages to measure the horizontal (surge) and vertical (heave) forces on the cylinder. The incoming waves are Stokes waves with a slope ranging from 0.06 to 0.24. The forces and waves are measured for 60 seconds with a sampling rate of 50 Hz. Among the recorded data, the first 10 waves are excluded because of transient behavior of the waves and the next The horizontal and vertical forces are analyzed up to 5th order harmonics. The horizontal forces are then compared to the values from the theoretical model called "FNV model". In addition, force transfer functions are also investigated. Major findings in this research are below. 1) The first order forces measured are slightly larger than the theoretical values of "FNV model" 2) The "FNV model" considerably overpredicts the second order forces. 3) The larger the amplitude and more extreme the wave slope, the smaller the predictions are compared to the experimental. 4) The higher harmonic forces are significantly smaller than the first harmonic force for all wave parameters. 5) The normalized forces vs. waves slopes are almost constant in the lower harmonics but vary a lot in the higher harmonics. 6) The trend of forces is more nonlinear in the horizontal forces than in the vertical forces as the wave slope increases. 7) The part of the results above is also observed by other researchers and confirmed again through the present work.

• 한국지반공학회논문집
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• 제19권4호
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• pp.155-165
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• 2003

본 연구는 고함수비의 액상준설토의 체적변화 및 퇴적특성을 파악하기 위해 일련의 실린더침강시험, 침투압밀시험과 2차원퇴적모형실험이 실시되었다. 그리고 실험결과는 실제 준설매립현장의 퇴적상태와 비교됨으로써 설계시에 필요한 침강에 의한 체적변화량을 구할 수 있도록 하였으며, 퇴적후의 세립토의 분포와 함수비 변화 등이 함에 조사되었다. 따라서 1차원 침강시는 실질토량이 증가 할 수록 퇴적고는 선형적으로 증가하며, 자중압밀개시시 및 완료시의 계면고도 또한 실질토량에 비례하여 증가되고 있다. 한편 2차원 퇴적모형실험에 의해 함수비의 분포와 세립토의 퇴적상태를 제시하였으며, 퇴적층의 함수비는 #200체의 통과량에 따라 다르며 최소 30%에서 최대 180%까지 폭넓게 분포되고 있다.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.133-140
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• 2007

The purpose of this study was to evaluate the effects of gasoline fuel to the LPI engine. Firing test bench was used in order to assess the effect on gasoline-injected LPI engine. Gasoline fuel was supplied into the reverse direction(3-4-2-1 cylinder) at 3.0 bar with commercial gasoline fuel pump. Engine test was performed using the firing test mode at end of line. The deviations of excess air ratio of each cylinder and maximum combustion pressure using gasoline fuel were within 0.1 and $1{\sim}2\;bar$. Engine start time was measured with changing coolant temperature at $20^{\circ}C,\;40^{\circ}C,\;80^{\circ}C$, respectively. Residual gasoline volume in the fuel line was measured about 32 cc after firing test and it was less than 2 cc within 10 seconds purging. To simulate the end of line, the residual gasoline in the fuel line was purged during 5 and 10 seconds. Start time of LPI engine with LPG fuel were 0.61 and 0.58 seconds. This work showed that severe problems such as misfiring and liner scuffing were not occurred applying gasoline fuel to LPI engine.

• 콘크리트학회논문집
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• 제16권1호
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• pp.27-35
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• 2004

지금까지 콘크리트에 대한 피로실험과 연구는 대부분 압축응력, 휨응력을 받는 경우에 대하여 연구를 진행하였으나 실제 교량이나 도로 포장콘크리트 구조물은 이축응력상태의 조합응력을 받게 된다. 따라서, 본 연구에서는 이러한 콘크리트 구조체가 받게 되는 이축응력 상태를 이상적으로 재현할 수 있는 쪼갬인장 피로실험방법을 제안하고 적용성을 평가 하고자 하였다. 실험은 ${\phi}15{\times}30cm$를 사용한 KS 규정을 응용하여 ${\phi}15{\times}7.5cm$의 시편을 제작하고, 쪼갬인장 피로실험에 적용하기 위한 타당성 검증을 수행하였으며, 이상적 탄성재료인 강재와 고체의 비교를 위하여 모르타르 시편을 제작하여 검증실험을 수행하였다. 또한, 이론적 고찰과 유한요소 해석을 수행하여 이론치와 해석치의 비교 고찰하였으며 정적 강도측정 및 게이지 부착실험을 수행하여 타당성을 입증하고자 하였다. 실험결과, FEA결과, 수평응력과 압축응력의 비는 3.1로 나타나 이론치 3.0과 유사한 결과를 얻을 수 있었다. 수평응력은 시편의 길이가 30cm일 경우 이론상 3MPa이지만, 본 연구에서는 시편의 길이가 30cm와 5cm일 때 각각 2.98MPa와 2.96MPa로 나타났다. 쪼갬인장 피로실험방법은 유한요소 해석, 정적 강도측정 및 게이지 부착실험모두에서 충분한 타당성을 나타내었으며, 이 방법은 실제 응력 모사, 실험의 간편성, 현장 시편 이용 가능성 등 많은 장점을 가지고 있는 것으로 판단되어 향후 교량이나 도로포장 구조물에 사용되는 콘크리트의 피로거동을 모사하는데 적합한 실험방법으로 사료된다.

• 한국기계가공학회지
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• 제10권6호
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• pp.50-55
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• 2011

The fluid power products are widely used in current industrial area such as automation of products and equipment assembly, high-tech machine tool, aircraft, train, and etc. As the development of industry is in progress, the development of the fluid power products is demanding and it is required in every industrial area. This research proposed a pneumatic system to evaluate displacement accuracy of the pneumatic actuator without external load and to analyze capability of integration of the valve system. The pneumatic system consisted of a combination of pneumatic actuator, four two-port valves, two three-port valves, two pressure valve, a check valve, two proximity sensors, and a program logic controller (PLC). The position controller is based on the PLC connected with the proximity sensors. The maximum air pressure applied for tests was $49.05N/cm^2$ and the displacement accuracy of a stroke was measured using a dial gauge. The supply- and discharge-side of air pressure and the length of the stroke of the pneumatic cylinder were varied The test of the position control of the pneumatic cylinder was carried out 50 times at each supply- and discharge-side air pressure of 24.53/34.34, 29.43/39.24, 34.34/44.15, and $39.24/49.05N/cm^2$ and replicated three times. The accuracy of the displacement of the pneumatic cylinder stroke increased as the supply- and discharge-side of air pressure increased with the stroke length of 133mm. Also the displacement accuracy increased as the stroke length increased with the fixed supply- and discharge-side of air pressure of the pneumatic cylinder as 34.34 and $44.15N/cm^2$, respectively. The most accurate displacement of the pneumatic cylinder was obtained at the supplyand discharge-side of air pressure of 39.24 and $49.05N/cm^2$, respectively, and strokes of 170 and 190mm.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.548-554
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• 2001

A GA(Genetic Algorithm) based 3D-PTV technique has been developed. The measurement system consists of three CCD cameras, Ar-ion laser, an image grabber and a host computer. The fundamental of the developed technique was based on that one-to-one correspondence is found between two tracer particles selected at two different image frames taking advantage of combinatorial optimization of the genetic algorithm. The fitness function controlling reproductive success in the genetic algorithm was expressed by a kind of continuum theory on the sparsely distributed particles in space. In order to verify the capability of the constructed measurement system, a performance test was made using the LES data set of an impinging jet. The developed 3D-PTV system was applied to the measurement of flow characteristics of the wake of a circular cylinder.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.633-640
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• 2007

In this paper, 3-D reciprocating compressor is taken into flow-structure interaction analysis. The full cycle process consisted of cylinder expansion and compression has been modeled without considering flow leakage through cylinder wall. Fully-coupled FSI analysis of this compressor model was iteratively solved and gives sufficient result with the experimental test. The study is emphasized to thoroughly investigate discharge valve motion, opening and closing, in order to determine discharge valve region which is prone to have high effective stress. The cylinder pressure is successfully validated before conducting impact analyses between discharge valve and other susceptible supported structure. Velocity profile has been obtained in FSI analysis is used as initial condition to carry out further impact analyses. Stress result of discharge valve and valve spring gives preliminary estimation of higher stress area due to its impact phenomena.

• 한국안광학회지
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• 제5권1호
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• pp.125-129
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• 2000

To fine understand the visual acuity of female old age. This study was researched the visual acuity test by the object and subject methods. The major findings was as follows: 1. The eye types were 80.94% positive for hyperopia. 13.86% for myopia and 5.19% for emmetropia respectively. 2. The anbormal refraction eye was positive for mixed astigmatism for 78.27%, myoptic com pound astigmatism (10.99%), simple presbyopia(4.97%), myopic simple astigmatism(2.88%), presbyopia compound astigmatism (1.57%), simple myopia(0.78%) and presbyopia simple astigmatism(0.52%). 3. The axis of astigmatism was 60.23% for against regular astigmatism. 22.73% for oblique astigmatism and 17.05% for regular astigmatism respectively. 4. On the total myopic spheric power, the -0.50 spheric equivalent ${\leq}-2.00$ was 90.2%, the -2.00${\leq}-6.00$ was 9.8%. 5. On the total presbyopic spheric power, the -0.50${\leq}-2.00$ was 80.252%, the -2.00${\leq}-6.00$ was 16.99% and 2.56% for anything over the 6.00 diopter. 6. On the astigmatic power, the $0.50{\geq}$ cylinder power${\geq}1.00$ was 69.35%,the 1.00> cylinder power ${\geq}2.00$ was 27.38%, and anything over the 2.00 cylinder diopter was 3.27%.

• 한국유체기계학회 논문집
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• 제9권6호
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• pp.54-62
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• 2006

An experiment about performance characteristics is conducted on a double chamber vane-type rotor. Three different rotors, which have 6, 8 and 9 vanes, are applied to the driver and various lift holes at the rear plate are used to increase the effective vane height. The inner diameter of a double chamber cylinder is ${\phi}27mm$, and the length of the cylinder is 65 mm. The maximum offset length between the rotor outer surface and the cylinder inner surface is 4.5 mm. In this study, specific output torques and powers are measured, and also noise and vibration are measured at the real operating situation. The operating torque on the double chamber is increased to 17% compared to the operating torque obtained at the single chamber which has the same size. The experimental results of noise and vibration show that the operating sound and vibration are directly related to the operating power generated by the double chamber rotor.