• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.102-108
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• 2002

Numerical simulations of 1, 2 dichloroethane(EDC) pyrolyisis are conducted to understand the process in the production of the vinyl chloride monomer (VCM) and by-products. A chemical kinetic mechanism Is developed, with the adopted scheme involving 44 gas-phase species and 260 elementary forward and backward reactions. Detailed sensitivity analyses and the rates of production analysis are performed on each of the reactions and the various species, respectively. The concentrations of EDC, VCM, and HCI predicted by this mechanism are in good agreement with those deduced from experiments of commercial and laboratory scale. The mechanism is found to accurately predict the EDC yield an(1 the production of by-products by varying the ranges of pyrolysis temperature, residence time, and pressure which impact on the pyrolysis of 1, 2 dichloroethane. The influence of reactions related to H atom on the relative sensitivity of EDC becomes important as the residence time increases. The pyrolysis of EDC mainly occurs through C$_2$H$_4$Cl$_2$+Cl=CH$_2$CICHI+HCI.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.38-41
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• 2002

Mammography is considered the single most important diagnostic tool in the early detection of breast cancer. Today's dedicated mammographic equipment, specially designed x-ray screen/film combinations, coupled with controlled film processing, produces excellent image quality and can detect very low contrast small lesions. In mammography, it is most important to produce consistent high-contrast, high-resolution images at the lowest radiation dose consistent with high image quality. Some of the major technical development milestones that have let to today's high quality in mammographic imaging are reviewed. Both the American College of Radiology Mammography Accreditation Program and the Mammography Quality Standards Act have significant impact on the improvement of the technical quality of mammographic images in the United States and worldwide. A most recent development in digital mammography has opened up avenues for improving diagnosis.

• 품질경영학회지
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• 제30권1호
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• pp.22-46
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• 2002

Recently, increasing attention has been paid to building the software quality and software productivity due to ongoing software crisis. To overcome such problem, one of the many alternatives is to use the capability maturity model (CMM) suggested by the Software Engineering Institute(SEI), focusing on the improvement of software progress. This research is proposed the theoretical framework for CMM based on the previous studies, and review the status of software process on the software development organization. We then examine the impact of the software process capability on the organizational performance including financial measures and non-financial measures. Hypotheses on software process capability were tested 144 organizational units. The 62.5% of foreign companies are distribute to the second and third level, the Korean firms in this study are indicated the first level. Result indicate that maturity of software process may be served the key predictor of organizational performance, in particular the positive relationship between the software process and non-financial performance index such as customer service, IT Infrastructure, marketing, supplier and purchaser, production and operation.

• 대한핵의학회지
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• 제36권1호
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• pp.19-27
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• 2002

The annual incidence of primary brain tumors is 7-19 cases per 100,000 people. The unique capacity of visualizing biochemical processes allows PET to determine functional metabolic activities of the brain tumors. Like other malignant tumors, F-18 FDG has been used commonly in the imaging of brain tumors. FDG PET is valuable in grading malignancy, predicting prognosis, monitoring treatment, differentiating tumor recurrence from radiation necrosis, and detecting primary lesion in metastatric brain tumors. Among amino acids labeled with positron emitters, C-11 methionine is used clinically. Tumor delineation is much better with methionine PET than with FDG PET. Low grade gliomas, in particular, are better evaluated with methionine than with FDG. PET opens another dimension in brain tumor imaging. PET imaging has clearly entered the clinical area with a profound impact on patient care in many indications.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.367.1-367
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• 2002

Recently, the noise environmental issue in compound residential areas like apartments becomes a very critical factor fer the building designers. In order to satisfy the customer need to live in a quiet environment, several interior structures for buildings are being introduced. The multi-layered composite floor plate is one of them. This structure is designed to prevent the noise generated by an object collision. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.354.2-354
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• 2002

The frequency response function(FRF) of each substructure is used in the transfer function synthesis method(TFS). The dynamic characteristics of an entire system are obtained by synthesizing results of substructures. The accuracy of TFS will depend on that of FRF of each substructure. The impact hammer testing is widely used to obtain the modal characteristics of substructures. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.356.2-356
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• 2002

Railway noise is one of the main causes of environmental impact. Whenever a new railway line is planned or a housing project near an existing railway is proposed, an estimate of the relevant levels is usually required. For this, it is necessary to quantify those parameters that affect the railway noise. Therefore we investigated the noise and vibration level which 107 high speed trains generated passing through the block of test railway track between Chunan and Chungwon. This paper presents the status and characteristics of the high speed railway noise and an accurate prediction of the high speed railway noise.

• 한국신뢰성학회지:신뢰성응용연구
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• 제2권2호
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• pp.121-133
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• 2002

This paper concerns informative censoring and some of the difficulties it creates in analysis of survival data. For analyzing censored data, misclassification of informative censoring into random censoring is often unavoidable. It is worthwhile to investigate the impact of neglecting informative censoring on the estimation of the parameters of the proportional hazards model. The proposed model includes a primary failure which can be censored informatively or randomly and a followup failure which may be censored randomly. Simulation shows that the loss is about 30% with regard to the confidence interval if we neglect the informative censoring.

• 한국철도학회논문집
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• 제5권4호
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• pp.215-221
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• 2002

In the standard specifications for the urban EMU (Electric Multiple Unit) train, there are several items to ensure safety against accidents. The 21st to the 23rd items have much to do with the crashworthiness of the urban EMU train. In this study, a rubber-tired Automated Guide-way Transit (AGT) System under development by KRRI is numerically evaluated from the point of view of crashworthiness by applying the above crashworthiness items. The numerical results show that the design of the AGT satisfies the 22nd and 23rd items. But a design modification to adopt mechanical fuses is recommended to reduce impact accelerations with respect to the 21st item.

• 한국철도학회논문집
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• 제5권4호
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• pp.231-236
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• 2002

Todays, crash safety requirements of the railway vehicle structures become important design criterion according to the increased driving speed and the lightweight construction. Although the crash analysis using computer simulation can be effectively applied to predict the crash performance of the railway vehicles in the early design stage, the optimized design w.r.t the crash safety could be realized by the crash tests with actual prototype vehicles. However, it is very expensive and time-consuming task to perform the crash test of the railway vehicles. As a measure to cope with the problem, in this paper, the scale modeling technique is suggested and experimentally verified to predict the impact energy absorption characteristics of full scale model of aluminum extrusions sub-structures and the high-speed railway vehicle structure.