• International Journal of Naval Architecture and Ocean Engineering
• /
• 제2권3호
• /
• pp.139-145
• /
• 2010

In the present study, we conducted resistance test, propeller open water test and self-propulsion test for a ship's resistance and propulsion performance, using computational fluid dynamics techniques, where a Reynolds-averaged Navier-Stokes equations solver was employed. For convenience of mesh generation, unstructured meshes were used in the bow and stern region of a ship, where the hull shape is formed of delicate curved surfaces. On the other hand, structured meshes were generated for the middle part of the hull and the rest of the domain, i.e., the region of relatively simple geometry. To facilitate the rotating propeller for propeller open water test and self-propulsion test, a sliding mesh technique was adopted. Free-surface effects were included by employing the volume of fluid method for multi-phase flows. The computational results were validated by comparing with the existing experimental data.

• 전기학회논문지
• /
• 제59권12호
• /
• pp.2256-2261
• /
• 2010

A corona discharge system with needle point or wire type corona electrode has been well used as an ionic wind blower. The corona discharge system with a needle point electrode produces ions at lower applied voltage effectively. However, the corona discharge on the needle point electrode transits to the arc discharge at lower voltage, and it is hard to obtain the elevated electric field in the discharge airgap for enhancing the ion migration velocity due to the weak Coulomb force. A cylindrical corona electrode with sharp round tip is reported as one of effective corona electrode, because of its higher breakdown voltage than that of the needle electrode. A basic study, for the effectiveness of cylindrical electrode shape on the ionic wind generation, has been investigated to obtain an maximum wind velocity, which however is the final goal for the real field application of this kind ionic wind blower. In this paper, a parametric study for maximizing the ionic wind velocity utilizing the cylindrical corona electrode and a maximum ion wind velocity of 4.1 m/s were obtained, which is about 1.8 times higher than that of 2.3m/s obtained with the needle corona electrode from the velocity profile.

• 한국정밀공학회지
• /
• 제21권12호
• /
• pp.100-108
• /
• 2004

In reverse engineering, data acquisition methodology can generally be categorized into contacting and non-contacting types. Recently, researches on hybrid or sensor fusion of the two types have been increasing. In addition, efficient construction of a geometric model from the measurement data is required, where considerable amount of user interaction to classify and localize regions of interest is inevitable. Our research focuses on the classification of each bounded region into a pre-defined feature shape fer a hybrid measuring scheme, where the overall procedures are described as fellows. Firstly, the physical model is digitized by a non-contacting laser scanner which rapidly provides cloud-of-points data. Secondly, the overall digitized data are approximated to a z-map model. Each bounding curve of a region of interest (featured area) can be 1.aced out based on our previous research. Then each confined area is systematically classified into one of the pre-defined feature types such as floor, wall, strip or volume, followed by a more accurate measuring step via a contacting probe. Assigned to each feature is a specific digitizing path topology which may reflect its own geometric character. The research can play an important role in minimizing user interaction at the stage of digitizing path planning.

• 한국컴퓨터그래픽스학회논문지
• /
• 제12권4호
• /
• pp.17-22
• /
• 2006

본 논문은 주어진 얼굴 사진에 대하여 자동으로 얼굴의 특징을 강조한 캐리커쳐 생성 기법을 제안한다. AAM(Active Appearance Model)을 사용하여 트레이닝 이미지의 특징점과 텍스쳐 정보를 유지하고 이것을 이용하여 평균 얼굴의 정보와 함께 주어진 얼굴에 대한 특징점을 찾아낸다. 캐리커쳐 아티스트들의 제안을 바탕으로 특징적인 부분을 과장하기 위한 룰을 정의하고 이를 입력 얼굴의 특징점에 적용하여 과장된 특징점을 얻는다. 마지막으로 주어진 사진에 대하여 좀 더 만화적인 효과를 내기 위해 얼굴 이미지에 카투닝을 적용한 다음 과장된 특징점으로 와핑한다. 이러한 방법으로 사용자의 조작을 최소로 하는 캐리커처 생성을 할 수 있다.

• 대한산업공학회지
• /
• 제23권3호
• /
• pp.533-544
• /
• 1997

Among numerous factors that have an effect on visual field, the effects of background condition on the size of the visual field were investigated to obtain more practical visual field that can be readily applicable to industrial settings. A visual experiment was conducted, in which the subject was instructed to search a target with distinct orientations. Size contrast, meridian, nontarget density, and subject's gender showed a significant effect on the size of the visual field at $\alpha=0.01$. The size of the visual field was linearly proportional to size contrast, and inversely proportional to density. Female's visual fields were found to be significantly larger than male subjects', The size of the visual field on horizontal axis was larger than that on vertical axis, and the size of the head & eye field on right meridian was also larger than that on left meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equations to predict the visual fields on the given background condition were suggested. The visual fields suggested in this study would be valuable to the design of visual displays and the panel layout of various displays and controls.

• Journal of Power Electronics
• /
• 제18권5호
• /
• pp.1479-1488
• /
• 2018

Power packet (PP) distribution system distributes power to different loads that share the same distribution cable in a packetized form. When compared with conventional power systems, a PP distribution system (PPDS) can reduce standby power, eliminate Point-of-Load (PoL) power conversion, and intelligently control the load demand from the source side. Due to the absence of PoL conversion, when multiple power sources at different voltage levels and conditioning requirements jointly send power to various loads at different voltage ratings, the generated voltage has an irregular shape. A large filter at each of the load sides is required to reduce such a large voltage ripple. In this paper, a single-inductor, multiple-input-single-output converter structure based multiple-energy-source mixer is proposed. It combines PP generation, maximum power point tracking (MPPT) of renewable energy sources (RESs) and filtering at the source side. To demonstrate the possible renewable energy integration, a PV panel is used as a power source together with other constant voltage sources. The PV power is approximately tracked using the constant voltage method and it is used for each of the PP generations. The proposed PP distribution system is experimentally verified and it is shown that a conventional PI controller is sufficient for stable system operation.

• 한국생산제조학회지
• /
• 제8권1호
• /
• pp.74-80
• /
• 1999

Recently, manufacturing work has been transformed to small scale production form with various types to act up to user's expectation from mass production with a little items required in the past. Then FMS using NC type machinaries has been applied actively also in domestic manufacturing line to meet thus tendency, but there are many machining troubles occured during work process not be settled yet. Nowdays high efficiently has been required no less than high precision in grinding work for the improvement of productivity. In this study, to represent more advance FMS can be adapted to thus situation In-process type monitoring method using AE and Current sensors is suggested to investigate the machining condition in grinding process. As results form this experimental study, it is recognized well that grinding conditions and dressing point of in time cab be estimated effectively using monitoring method suggested. Furthermore, surface shape of grinding wheel on voluntary point of in time can be predicted indirectly through the observation and comparison of AE signal waveform obtained as performance of continuous dressing work.

• 한국버섯학회지
• /
• 제11권1호
• /
• pp.9-14
• /
• 2013

표고 "수향고"는 Di-mon 교잡에 의해 육성되어 품종으로 등록요건에 적합한 조건시험을 거쳐 품종출원 되었다. 균사생장은 $25^{\circ}$에서 가장 우수하였다. 버섯의 형태는 평반구형의 대엽, 후육으로 갓직경은 약 52mm이고 갓의 두께는 약 17mm이다. 주름살 측면은 평활형이며 주름살 폭은 보통으로 갓과 대의 위치는 중심생이고 갓의 가장자리에 인피가 있다. 도목살수에 의한 버섯발생에 적합한 품종으로 집중발생형이다. 버섯의 발이온도는 $18{\sim}28^{\circ}$로 발생시기가 6월, 8~9월인 고온성 품종이다. 재배시험지에서 4년간 $140kg/m^3$의 표고가 생산되었다.

• 신재생에너지
• /
• 제7권2호
• /
• pp.51-58
• /
• 2011

Saemankeum is well known for its high speed wind, and it is known that the blueprint of a future city around Saemankeum, including new industrial complex, has been planned. As a result, large-scale offshore wind farm, on the basis of the measurement of wind resource for a long time, can be considered, so that generated electricity can be used to meet the energy demand near the wind farm. Wind speed in Kokunsando of Saemankeum is measured and analyzed with its statistical distribution and wind directions. The probability of wind power resource over Kokunsando of Saemangeum is reviewed with the measured data in one island of Kokunsando. According to measured data, the shape and scale factor of Weibull distribution of wind speed are obtained, and then power density is analyzed as well. Through this study, it is clear that the Saemangeum area has a fluent and abundant wind power source to develop the wind farm in Korea.

• 대한산업공학회지
• /
• 제19권2호
• /
• pp.53-64
• /
• 1993

Successful completion of a visual task in a predetermined time is very crucial to many operations such as piloting an aircraft. Although existing ergonomic interface models often provide a function of vision tests, it determines only the visibility at any given location. To complement this problem in existing models, the isoresponse time region considering the factors related to visual tasks is presented. Using a multiple regression model, equal response time regions were obtained within which mean response time is expected to be the same and is asymmetrical in shape. Among the factors considered, expectancy significantly decreased response time, and when cued, the effects of field heterogeneity, target uncertainty, density, size contrast and peripheral position on search time were less significant than those in unexpected cases. Response time and error rate, gender and visual acuity were not significantly correlated, and response time and age was positively correlated. These results are expected to be directly applicable to designing various visual tasks in real-life situations.