• 마이크로전자및패키징학회지
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• 제17권4호
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• pp.27-33
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• 2010

We have successfully demonstrated a high-pin-count and thin embedded-LSI package to realize next generation's mobile terminals. The following three design key points were applied: (i) Using Cu posts, (ii) Using the coreless structure, (iii) Using a Cu plate as the ground plane. In order to quantitatively determine the contribution of the three points, the five-stage process for reducing the number of metal layers is described by means of the electrical simulation. The point-(i) and (ii) are effective from the viewpoint of the power integrity (PI); that is, these points play important roles in reducing the number of metal layers, and especially the point-(ii) contributes at least twice as the point-(i). The point-(iii) is not effective in the PI, but has a few effects on the signal integrity (SI). For reducing the number of metal layers, we should, at first, pay attention whether the PI characteristics fulfill the specification, and then we should confirm the SI characteristics.

• 한국농공학회논문집
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• 제58권4호
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• pp.85-95
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• 2016

PBT (Plate Bearing Test) is a commonly used compaction estimation used to provide basal support for embankments. This study presents the results from experimental evaluations PBT, LWDT (Light Drop Weight Tester) test and Geogauge test with embankment materials which consist in sandy soil, crushed stone and rock. The results of this study indicate that the regression analyze results (r) from test results between Young's modulus and $k_{30}$, $E_v$ are 0.385 and 0.111~0.496, estimated very lack of correlation. The Geogauge is frequency vibration from machine to underground. Geogauge can not measure to accuracy test results when it is used on ground of the rock or crushed stone. The regression analyze results (r) from $E_v$ and Dynamic modulus are 0.502~0.847, different estimated by calculate method, as it were, when calculate $E_v$, least square method are appeared more accuracy than gradient of secant.

• 대한기계학회논문집B
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• 제26권6호
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• pp.772-778
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• 2002

A numerical analysis of turbulent gas-particle two-phase flow is performed in conjunction with the experiments of Fackrell ＆ Robins and Raupach & Legg that considered ground-level source and/or elevated source flat plate flow. K-$\omega$ turbulence model is used in order to analyze fully turbulent flow field and the concentration equation with settling velocity is adopted for the concentration field. The model of Einstein and Chien is applied that couples the velocity field and the concentration field. Turbulent eddy viscosity is re-evaluated in this model. The present numerical results have good agreement between the simulation and the experimental data for the mean flow velocities and particle concentrations. While the previous study shows about 27% error in the vicinity of the source of particle concentration, the .present study allows about 14% error. A new turbulent gas-particle flow model developed by this study is able to cut down error by 13% at a near source.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1160-1165
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• 2004

The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces of the ankle joint during the waist pulling, and to assess the ankle joint reaction forces according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 cameras, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and joint reaction forces during the recovery of postural balance control. From the experiment using falling mass perturbation, joint moments were larger than those from the experiment using air cylinder pulling system with milder perturbation. However, JRF were similar nevertheless the difference in joint moment. From this finding, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movement of flexion or extension or compensating joint reaction force with surrounding soft tissues. Therefore, biomechanical analysis of human ankle joint presented in this study is considered useful for understanding balance control and ankle injury mechanism.

• Coupled systems mechanics
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• 제1권4호
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• pp.311-324
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• 2012

Previous investigations have demonstrated that strong earthquakes can cause severe damage or collapse to storage tanks. Theoretical studies by other researchers have shown that allowing the tank to uplift generally reduces the base shear and the base moment. This paper provides the necessary experimental confirmation of some of the numerical finding by other researchers. This paper reports on a series of experiments of a model tank containing water using a shake table. A comparison of the seismic behaviour of a fixed base system (tank with anchorage) and a system free to uplift (tank without anchorage) is considered. The six ground motions are scaled to the design spectrum provided by New Zealand Standard 1170.5 (2004) and a range of aspect ratios (height/radius) is considered. Measurements were made of the impulsive acceleration, the horizontal displacement of the top of the tank and uplift of the base plate. A preliminary comparison between the experimental results and the recommendations provided by the liquid storage tank design recommendations of the New Zealand Society for Earthquake Engineering is included. The measurement of anchorage forces required to avoid uplift under varying conditions will be discussed.

• Wind and Structures
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• 제26권5호
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• pp.317-329
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• 2018

Wake characteristics of the flow over a finite square prism at different incidence angles were experimentally investigated using an open-loop wind tunnel. A finite square prism with a width D = 15 mm and a height H = 7D was vertically mounted on a horizontal flat plate. The Reynolds number was varied from $6.5{\times}10^3$ to $28.5{\times}10^3$ and the incidence angle ${\alpha}$ was changed from $0^{\circ}$ to $45^{\circ}$. The ratio of boundary layer thickness to the prism height was about ${\delta}/H=7%$. The time-averaged velocity, turbulence intensity and the vortex shedding frequency were obtained through a single-component hotwire probe. Power spectrum of the streamwise velocity fluctuations revealed that the tip and base vortices shed at the same frequency as that ofspanwise vortices. Furthermore, the results showed that the critical incidence angle corresponding to the maximum Strouhal number and minimum wake width occurs at ${\alpha}_{cr}=15^{\circ}$ which is equal to that reported for an infinite prism. There is a reduction in the size of the wake region along the height of the prism when moving away from the ground plane towards the free end.

• 한국해양환경ㆍ에너지학회지
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• 제5권2호
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• pp.19-27
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• 2002

본 연구는 입체적 어장 개발을 위해 수산자원 증대의 토대가 되는 해조장의 확대와 생태계의 고밀도·고효율화를 위한 기초적 연구로 수평판형 중층계류식 인공해저시스템의 파랑응답특성에 관한 실험적 연구를 수행하였다. 실험은 2차원 수조에서 다른 두 가지 모형의 수평판을 세 가지 다른 수심에 각각 고정 혹은 계류시켜 실시하였다. 실험에서 모형 고정시의 작용유체력 특성과 모형 계류시의 파랑응답 및 계류력 특성을 살펴보았으며, 또 각 조건에서 모형의 파랑제어특성을 검토하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.299-303
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• 2004

본 논문은 주파수 변조 연속파 레이더를 사용하여 화물 선박의 탱크의 내용물의 깊이를 측정하는 레벨 센서의 개발에 관한 것이다. 사용 주파수는 10~11 GHz를 이용하였으며, 테스트용 물체는 RCS가 0.8 $m^2$인 도체판을 사용하였다. 실험은 연구실 내부와 운동장에서 하였으며, 스윕 주기가 100 ms, 안테나 이득이 약 20 dBi인 사각형 혼 안테나를 사용하여 약 5 dBm의 신호를 안테나에 인가하여, 40 m 까지 물체를 움직이며 비트주파수를 측정하여 이론치와 비교하였다. 실험치와 이론치가 잘 일치하였으나 전압제어 발진기의 비선형으로 인해 분해능이 약 10 cm 정도로 측정되었다.

• Mycobiology
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• 제33권3호
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• pp.150-157
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• 2005

The fungal flora decomposing rice straw were investigated all over the soil of Sharkia Province, east of Nile Delta, Egypt, using the nylon net bag technique. Sixty-four straw-decomposing species belonging to 30 genera were isolated by the dilution plate method in ground rice straw-Czapek's agar medium at pH 6. The plates were incubated separately at $5^{\circ}C,\;25^{\circ}C\;and\;45^{\circ}C$, respectively. Twenty nine species belonging to 14 genera were isolated at $5^{\circ}C$. The most frequent genus was Penicillium (seven species), and the next frequent genera were Acremonium (three species), Fusarium (three species), Alternaria, Chaetomium, Cladosporium, Mucor, Stachybotrys (two species) and Rhizopus stolonifer. At $25^{\circ}C$, 47 species belonging to 24 genera were isolated. The most frequent genus was Aspergillus (nine species), and the next frequent genera were ranked by Penicillium (five species), Chaetomium (three species), Fusarium (three species). Each of Alternaria, Cladosporium, Mucor, Myrothecium and Trichoderma was represented by two species. At $45^{\circ}C$, 15 species belonging to seven genera were isolated. These were seven species of Aspergillus, two species of Chaetomium and two species of Emericella, while Humicola, Malbranchea, Rhizomucor and Talaromyces were represented by one species respectively. The total counts of fungi the genera, and species per gram of dry straw were significantly affected by incubation temperature and soil analysis (P < 0.05).

• 한국융합학회논문지
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• 제8권5호
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• pp.155-160
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• 2017

트랙터는 각종 작물을 생산하는 농용작업 외에 건설작업, 임야작업, 가정용 등에 사용되는 다목적 작업차량으로 경작용의 가래, 쟁기, 써레, 수확기 등을 견인하는 농업 작업에 없어서는 안 되는 필수 장비이다. 트랙터 운전자의 작업공간인 캐빈은 트랙터가 전도되었을 때 운전자가 입게 될 피해를 최소화하고 운전자가 전락하여 상해를 입지 않도록 보호하여야 한다. 일반적으로 캐빈은 프레임과 판들의 용접으로 제작되기 때문에 용접상태에 따라 구조물의 강성이 크게 영향을 받게 된다. 본 연구에서는 유한요소 해석을 이용하여 캐빈의 제작 시 예상되는 구조물의 용접 오차가 캐빈 구조물의 정적, 동적 강성에 미치는 영향을 파악하고, 캐빈의 강성을 확보하기 위한 방안을 제시하고자 한다.