• 한국해양공학회지
• /
• 제12권1호
• /
• pp.113-119
• /
• 1998

An experimental study was carried out in a three-dimensional cubic cavity driven by 2-dimensional plane Poiseuille flow for three kinds of Reynolds number, $10^4$, 3 $\times$ $10^4$ and 5 $\times$ $10^4$ based on the cavity width and cavity inlet mean flow velcoity. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system. Laser based illumination and two-frame grey-level cross correlation algorithm are adopted. Severe unsteady flow fluctuation within the cavity are remarkable at above Re = 3 $\times$ $10^4$ Reynolds numbers and sheared mixing layer phenomena are also found at the region where inlet driving Poiseuille flow is collided with the clock-wise rotating main primary vortex at upper center area. Instant velocity profiles reveal that deformed forced vortex formation is observed throughout the separate two areas.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2002년도 하계학술발표회
• /
• pp.162-163
• /
• 2002

1-D photonic band-gap structure is identified in a cholesteric liquid crystal system. The optical transmission spectrum is measured and compared with the theoretical analysis. Nonlinear transmission is measured near the band edge. Also 3-D photonic band-gap structures are fabricated from dielectric colloidal polystyrene beads through a centrifuge method. The fabricated photonic crystals exhibit opalescent colors under white light and show a clear diffraction peak dependent on the incident angle of the light beam. Also the scanning electron microscope image was taken to verify the face-centered cubic crystal structure. Bragg's law and Snell's law are employed to describe the position of angle resolved diffraction peaks. It was shown that the optically deduced effective refractive index and lattice constants were in good agreement with the crystal structure identified by scanning electron microscope.

• 한국전산유체공학회지
• /
• 제9권2호
• /
• pp.62-69
• /
• 2004

The present work solved 3D incompressible RANS equations on a rotating, multi-blocked grid system to efficiently analyze ducted marine propulsor with the interaction of propeller guidevane and annular duct. To handle the interface boundary between the guidevane and the propeller, a sliding multiblock technique based on the cubic spline interpolation was applied. To validate the present code, a turbine flow was simulated and the time-averaged pressure coefficients were compared with experiment. After the code validation, the flowfield around a ducted marine propeller with pre-swirl guidevane was simulated.

• 한국정밀공학회지
• /
• 제19권11호
• /
• pp.160-166
• /
• 2002

In this paper, data acquisition and analysis of a measuring machine for marine engine's cams is discussed. A rotary encoder and linear scale of the machine to measure angular and linear displacement respectively are interfaced to the PC via encoder board with 2 channels. The design and measuring data are interpolated by cubic spline curves to compute the precision error which is defined by the maximum and minimum distances between two curves. The minimum zone fit of ISO is employed to evaluate the geometric deviation. The developed system takes only 5 minutes to measure and analyze while the CMM takes over 1 hours even with a skilled operator.

• 대한기계학회논문집A
• /
• 제32권3호
• /
• pp.250-257
• /
• 2008

We calculate the variation of the surface stresses according to uniaxial and biaxial strains in face-centered cubic (FCC) metals. In our study, three mainly observed free surfaces of seven representative FCC metals are considered. Employed method is molecular mechanics, in which the interaction of atoms is described by empirical interatomic potentials. As uniaxial strain increases to tensile direction, the surface stresses on {100} and {110} free surfaces decrease monotonously, while those on {111} surface increase. These tendencies are the same regardless of the species of metals and interatomic potentials employed. However, when the system is under biaxial strain, surface stresses change different according to the surface directions, the species of metals, and even interatomic potentials. On {100} and {111} surfaces, heavy metals (Pt, Au) show the opposite variation to light metals (Ni, Cu). In the cases of Pd and Ag, the surface stresses reveal the opposite tendency, depending on interatomic potentials used.

• 한국소음진동공학회논문집
• /
• 제17권5호
• /
• pp.427-436
• /
• 2007

The catenary of a high-speed electrical train is modeled by the finite elements with the upper suspension wire, lower contact wire, and droppers, and the dynamic contact between the catenary and the pantograph is numerically analyzed by solving the whole equations of motion of the pantograph and the catenary system subjected to the contact condition. For the stability of the numerical solution, with the cubic spline interpolation of the catenary displacement, the velocity and acceleration constraints as well as the displacement constraint are imposed on the contact point. Through the various numerical examples, it is shown that the dropper positions as well as the static deflection are crucial to determine the contact and separation of the pantograph of a high-speed train.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.594-597
• /
• 2007

The notebook system use the radial fan to cool the main chipsets which generate heat. It needs to improve cooling performance by increasing fan RPM or increasing fan volume. But the former accompanies acoustic noise problem and the latter has a limitation due to notebook height and cooling area. So this study shows fatal parameters in the fan performance view point, and optimization process with Design Of Experiment. With this result, the fan CFM increases with same size of fan and we can use it as a result of decreasing fan acoustic noise.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
• /
• pp.133-137
• /
• 2000

Form-ratio means the ratio of Height/Width/Depth in 3-dimensions. The golden ratio or golden section is included as one of the form-ratio. Kansei Engineering System has some basic design databases. Form-ratio and color are basic design elements and they are very important for designing various products in viewpoint of Kansei Engineering. The subjects evaluate the form-ratios of 3-dimensional cubes and virtual products (refrigerator) with SD-scale kansei words(feelings and images). The golden ration was evaluated as "not beautiful" in refrigerator. We compared with the kansei of cube model and virtual product, and obtained databases of the relationship between the form-ratio and kansei.

• 한국멀티미디어학회:학술대회논문집
• /
• 한국멀티미디어학회 2001년도 춘계학술발표논문집
• /
• pp.33-36
• /
• 2001

LCL은 컨테이너에 화물을 적재할 때 한 화주가 컨테이너의 공간을 전부 사용하는 FCL과 달리 여러 명의 화주가 각자의 화물을 한 컨테이너에 적재하는 방식을 말한다. 기존의 LCL 화물 선적은 화주의 요청에 의하여 선주가 Forward를 통하거나 이전에 거래하던 화주를 통하여 화물을 모집하여 남는 CBM(Cubic Miter)를 태우게 된다. 본 논문에서는 이들을 웹 상에서 서비스하는 LCL 화물 정보시스템을 제안한다. 이 시스템은 화주와 선주의 정보를 시스템을 통하여 다른 화주나 선주에게 제공하는 한편 이들 정보들을 바탕으로 LCL 선적할 화주의 결정에 필요한 적절한 정책은 시스템의 Agent들에 의해서 이루어진다. 그리고 데이터베이스의 접근에 있어서도 CORBA를 이용하여 이 기종의 시스템들에 분산된 데이터베이스에 쉽게 접근할 수 있도록 하여 보다 많은 정보를 바탕으로 시스템을 운영할 수 있다.

• 대한임베디드공학회논문지
• /
• 제1권1호
• /
• pp.20-23
• /
• 2006

본 논문은 MB-OFDM UWB(Multi Band-Orthogonal Frequency Division Multiplexing Ultra Wide Band) 시스템을 위한 변형된 가변 파라미터를 이용한 큐빅 인터폴레이터를 제안한다. MB-OFDM UWB 시스템은 고속의 동작속도가 필요하기 때문에, 기존 가변 파라미터를 이용한 큐빅 인터폴레이터에 병렬 처리 기술과 파이프라인 기법을 동시에 적용한다. 실험 결과, Stratix II 2S60F101020C3 디바이스를 타켓으로 최대지연경로 속도와 최대지연경로 주기가 각각 최대 88.79MHz와 11.262ns가 되었고, 동작속도는 최대 대략 200% 이상 향상되었음을 알 수 있다.