• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1376-1378
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• 1999

Most conventional protection relays are based on processing information in the spectrum that is close to or at power frequency. It is, however, widely known that faults on transmission lines produce frequency components of a wide range In this respect, this paper describes the basis of a Protection technique for transmission lines which utilises high-frequency components. Fault-generated signals caused by post-fault and the signal derived from stack tuner is connected to the coupling capacitor of CVT. Digital signal processing is then applied to the captured information to determine whether the fault is inside or outside the Protected zone, and to discriminate the fault type on transmission line.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1373-1375
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• 1999

High impedance fault (HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equiment damage or personal threat. This paper proposes the model of HIF in transmission line using the ZnO arrester and resistance to be implemented within EMTP. Wavelet transform is efficient and useful for the detection of HIF in power system, because it uses variable windows according to frequency. HIF detection method using wavelet transform can distinguish HIF from similar phenomena like arcfurance load, capacitor bank switching and line switching.

• 한국공간구조학회논문집
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• 제4권3호
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• pp.57-63
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• 2004

철근 콘크리트보에 개구부를 설치하여 실내공간을 효율적으로 사용하기 위해 시공되는 유공보는 웨브부분의 단면결손으로 인해 전단력이 지배적으로 작용하는 보를 대상으로 많은 연구가 이루어져 왔으며, 연구내용 또한 보의 전단내력 및 거동에 대한 것이었다. 본 연구에 있어서는 철근콘크리트 유공보 중 휨모멘트가 지배적으로 작용하는 보를 대상으로 내력 및 거동을 규명하는 것을 목적으로 하고 있다. 이를 위하여 7개의 실험체를 제작하였으며, 실험의 변수는 유공의 크기 및 보강유무이다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제27권1호
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• pp.83-86
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• 2001

Myoepithelioma is histologically composed exclusively of myoepithelial cells. Myoepithelial cells are present in the major and minor salivary glands. Salivary gland neoplasms that frequently contain myoepithelial cells are the pleomorphic adenoma, adenoid-cystic carcinoma, and epithelial myoepithelial carcinoma of intercalated duct origin. Neoplasms composed exclusively of myoepithelial cells are rare. Myoepitheliomas may be composed of spindle-shaped cells, plasmacytoid(hyaline) cells, or combination of both in varying proportions. A case is reported of plasmacytoid myoepithelioma with ultrastructural confirmation, together with reviews of the English literature.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권4호
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• pp.297-306
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• 2007

Distraction osteogenesis was pioneered by Ilizarov in the treatment of injured extremities. Its subsequent application to Oral and Maxillofacial Surgery has opened a new chapter in the treatment of facial deformity. Careful monitoring of the period of distraction and consolidation of the callus is important and has been well described. Complications, such as infection, haematoma and premature ossification, are difficult to diagnose and can compromise the outcome after the surgery. Too slow rate of distraction results in premature fusion of cortices and too rapid information of bone 'cyst' within the callus distraction. I experienced 2 patients of congenital unilateral mandibular hypoplasia, so called Hemifacial Microsomia. After distraction surgery, I evaluated callus formation of mandibular distraction with Ultrasound Sonography during distraction and consolidation period. Plain radiography, although it enables accurate measurement of the distraction gap, did not give sufficient detail to allow assessment of early stages of bone formation, But, ultrasound monitoring could enable continuous monitoring of the distraction gap without exposure to ionizing radiation and allow detection of fine detail, which may influence manipulation of the callus.

• Journal of Advanced Marine Engineering and Technology
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• 제18권3호
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• pp.26-33
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• 1994

A new reliable method to prediet the axial vapor fraction distribution from the measured probability density of the liquid bulk temperature is suggested in this paper. And also the actual quality of the subcooled boiling flow is easily calculated from the liquid bulk temperature. When the heat generating rate is reached to the CHF value, the sharp wall temperature increasing by the wall temperature fluctuation is occurred under the CHF condition. This paper presents the simple wall temperature fluctuation model of transition boiling by the repeating process of overheating and quenching, when the coalescent bubble passes slowly near the wall. Experiments for the subcooled R-113 flow are carride-out in the range of(0.9399~4.461)${\times}10^6$kg/$m^2$hr mass velocity and 10~3$0^{\circ}C$ intel subcooling condition.

• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.73-80
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• 1994

The water ejector is a low pressure high flow rate volumetric pump. It utilize the energy of a low mass flow, high velocity stream to induce a large mass flow, low velocity stream. In addition, it has a very good resistances to cavitation compared to the other type of pumps, and the maintenance cost is practically nil. There has been enormous energy loss to supply the upper part water of dam which has large potential energy as mere irrigation water in domestic multipurpose dam. The new type of energy saving system which developed through the present study can economizes over 950,000 kWh per year by mixing the upper part water of dam with the waste water by the large water ejector. This paper estimates the economical efficiency of the new type of irrigation water pumping system, and further more, represents the change of performance characteristics of large water ejector, which was adapted to this system, according to the fluctuation of upper water level that seasonally changes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.491-495
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• 2008

The effects of vehicles and pavement surface types on noise have been investigated at the Korea Expressway Corporation's Test Road along the southbound side of the Jungbu Inland Expressway, South Korea. The study was conducted in 2005 and 2006 through field measurements at nine surface sections of asphalt concrete and Portland cement concrete pavements using eleven vehicles. For the road noise analysis, the sound power levels (PWLs) of combined noise (e.g., tire/pavement interaction noise and power-train noise together) and tire/pavement interaction noise using various vehicles were calculated based on the novel close proximity (NCPX) and pass-by methods. Then, the characteristics of the PWLs were evaluated according to surface type, vehicle type, and vehicle speed. The results show that the PWLs of vehicles are diversely affected by vehicle speed and the condition of the road surface.

• 한국전자거래학회지
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• 제5권1호
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• pp.1-18
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• 2000

As the networks (i.e., intranet and internet) proliferate all over the world, it is inevitable to move some (or all) of the enterprise activities into virtual spaces. Differently from business data, product data have complex semantics and thus are not properly exchanged among different application programs. Even though some neutral formats of product data have been developed by standard organizations, translating them among various application programs still needs the comprehensive understanding of the complex semantics. Recently, it is widely recognized that capturing more knowledge is the next step In overcome the current difficulties on sharing product data. In this paper, we present Web-based knowledge management that facilitates seamless sharing of product data among various application programs in virtual enterprises. Three types of knowledge are managed by the knowledge management system - metadata, ontology, and mapping. In this environment, we consider both business applications (e.g., ERP, SCM, and EDI System) and engineering applications (e.g., CAD and CAM system).

• 펄프종이기술
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• 제34권2호
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• pp.13-21
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• 2002

A new method for measuring fiber length and fiber coarseness was developed using image analysis technique. Measured fibers were transferred to a glass slide on a filter paper placed on a wire of the laboratory paper machine. After staining the fibers on the slide, mean fiber lengths and coarseness were measured by a commercial image analysis software, named KS400. The resultant data obtained from the image analysis displayed a close correlation with those from FS-200 and also showed excellent reproducibility as well as those from FS-200. The length of synthetic fibers over 10 mm long could be readily measured by this new analysis technique. Finally, a substantial improvement in precision for measuring fiber length and coarseness was made with less operator's effort for a given time.