• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.161-172
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• 2008

The level of service (LOS) evaluation method of the Highway Capacity Manual (HCM) is limited to intersections with pre-timed signal operation, while advanced real-time traffic control systems have been expending in the field. This paper proposes a preliminary framework for LOS analysis at isolated intersections controlled by COSMOS, the real-time traffic control systems robustly utilizing the degree of saturation as basic inputs. The proposed LOS evaluation framework was devised with a pilot model developed to estimate the average cycle length and green times of COSMOS. The validation test showed that the proposed framework was able to accurately project the LOS, which was separately evaluated based upon field data.

• Korean Journal of Hydrosciences
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• v.5
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• pp.17-31
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• 1994

Because of the Keumkangsan-Dam and the Peace-Dam constructed in recent years, it is expected that the peak flood discharge and the peak flood stage at the Hwachun-Dam site have been changed. In this study, two methods were used to simulate and compare the effects of the upstream dam construction on the change of the discharge and the stage. One is the storage function method widely used for the hydrological routing in the country. The other is the DWOPER(Dynamic Wave Operational Model) package conducted on four different scenarios: (1) before the construction of the Keumkangsan-Dam and the Peace-Dam; (2) the exclusion of the Keumkangsan-Dam watershed (before the construction of the Peace-Dam); (3) the exclusion of the Keumkangsan-Dam watershed (after the construction of the Peace-Dam) ; (4) the exclusion of the Peace-Dam watershed. The results of the four test cases from the two methods show that the peak flood discharge and the peak flood stage at the Hwachun-Dam site are reduced due to the construction of the Peace-Dam. From these findings, it is suggested that the operational criteria for the optimal dam-operation of the Hwachun-Dam need to be modified.

• Journal of Veterinary Clinics
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• v.20 no.4
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• pp.458-466
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• 2003

The bone regeneration effects of copper oxide on experimentally induced fibular fracture were examined in 36 New Zealand white male rabbits. They were divided into two groups: non-treated group (control group) and copper oxide treated group (treatment group). A fibular fracture was created by an osteotomy in the middle of the fibula and 62.5 mg/kg of copper oxide was orally administrated during 7 days after operation in the treatment group. Radiological findings, histopathological examinations and hematoserological findings were observed to evaluate the bone regeneration effects of copper oxide on fibula fracture during 9 weeks. In radiological findings, the area of bone regeneration at the fracture site of the treatment group was significantly wider from 3 weeks to 6 weeks after administration of copper oxide than those of the control group (p < 0.05). In histopathological examinations, fracture healing in treatment group was faster than in control group. Also, histopathological responses of thick bony trabeculae and new bone marrow formation were shown in the treatment group, whereas many fibrous tissues and cartilages were mainly observed in the control group. No specific effects of copper oxide on the body was found in hematological and serological test during experimental period. These results showed that the copper oxide had a potential therapeutic application in the treatment of fracture and bone trauma.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.1-7
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• 2013

In nuclear power plants, lined carbon steel pipes or PCCPs (pre-stressed concrete cylinder pipes) have been widely used for sea water transport systems. However, de-bonding of linings and oxidation of PCCP could make problems in aged NPPs (nuclear power plants). Recently at several NPPs in the United States, the PCCPs or lined carbon steel pipes of the sea water or raw water system have been replaced with HDPE (high density polyethylene) pipes, which have outstanding resistance to oxidation and seismic loading. ASME B&PV Code committee developed Code Case N-755, which describes rules for the construction of buried Safety Class 3 polyethylene pressure piping systems. Although US NRC permitted HDPE materials for Class 3 buried piping, their permission was limited to only 10-year operation because of several concerns including the quality of fusion zone of HDPE. In this study, various requirements for fusion qualification test of HDPE and some regulatory issues raised during HDPE application review in foreign NPPs are introduced.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.574-581
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• 2012

Condition-based maintenance(CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance strategy as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.840-845
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• 2014

Vibration profiles consist of two kinds of pattern, random and harmonic, at general engineering problems and the detailed vibration test mode of a target system is decided by the spectral condition that is exposed under operation. In moving mobility, random responses come generally from road source; whereas the harmonic responses are triggered from rotating machinery parts, such as combustion engine or drive shaft. Different spectral input may accumulate different damage in frequency domain since the accumulated fatigue damage dependent on the pattern of input spectrum in high cyclic loading condition. To evaluate the sensitivity of spectral damage according to different loading conditions, a linear elastic system is introduced to conduct a uniaxial vibration testing. Measured data, acceleration and strain, is analyzed using energy isocline function and then, the calculated fatigue damage is compared by different loading cases, random and harmonic.

• Asia pacific journal of information systems
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• v.16 no.3
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• pp.29-47
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• 2006

Many companies have been implementing Enterprise resource planning (ERP) systems for their organizational transformation in order to survive and achieve strategic advantages in an increasing competitive business environment. Thus, it is meaningful to identify factors that affect ERP system operation positively. Organizational citizenship behaviors (OCB) are discretionary, extra-role behaviors of employees which go beyond the prescribed formal roles, and are known as to be the contribution factors for organization performance. The purpose of this study is to develop the measurements for the OCB constructs in ERP system context and empirically test the relationships between the OCB construct and ERP system success. The four constructs - altruism, conscientiousness and courtesy, civic virtue, and sportsmanship - and fifteen measurements on the OCB were developed based on previous studies (i.e. Organ 1988) and empirically verified by confirmatory factor analysis. The results of testing the relationships between the OCB and ERP system success show that the OCB have a significant direct impact on the information quality and intention of IT innovation while they have an indirect impact on work efficiency mediated by information quality. This study enhances the OCB model into information system arena and helps better understand the user behaviors of information systems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.3 s.246
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• pp.208-214
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• 2006

Dimethoxy methane$(CH_3-O-CH_2-O-CH_3)$, also known as methylal or DMM, is an oxygenated additive that contains 42.5% oxygen by weight and is soluble in diesel fuel. It is a colorless liquid and a gas-to-liquid chemical 방tat has been evaluated for use as a diesel fuel component. Experiments were conducted by using the five blends with different volumetric percentage of DMM(2.5, 5, 7.5, 10, and 12.5%) in baseline diesel fuel. The test engine was single cylinder, four stroke, DI diesel engine unmodified. Also, data was collected for steady state operation at 24 engine speed-load conditions. The focus of this study was to investigate the effects of the addition of oxygenated fuel to diesel fuel on the engine-out emissions and the performance. Smoke emissions of all DMM blends were reduced substantially in comparison with conventional diesel fuel. These results indicate that DMM may be an effective blendstock for diesel fuel as an environment-friendly alternative fuel. Besides, this study showed that simultaneous reduction of smoke and NOx emissions could be achieved by oxygenated fuel and EGR method that was applied to decrease NOx emissions increasing with smoke emissions reduction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1384-1389
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• 2004

As operating time of heat exchangers progresses, fouling generated by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of domestic nuclear power plants have been analyzed in terms of the heat flux and heat transfer coefficient at test conditions as a means of heat exchanger management. Except for the fouling level generated in operation of heat exchangers, also, all of the tubes of heat exchangers have been replaced when the number of plugged tubes exceeds the plugging criteria based on design performance sheet. This paper describes the plugging margin evaluation mettled reflected the fouling of shell-and-tube heat exchangers, which can evaluate the thermal performance for heat exchangers, estimate the future fouling variations, and reflect the current fouling level. To identify the effectiveness of the developed method, the fouling and plugging margin evaluations were performed for a component cooling heat exchanger in a nuclear power plant.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.193-198
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• 2004

In order to keep the market competitiveness, it is desirable for automotive manufacturer to meet the customer's various aspects of requirements. The overall NVH (Noise, Vibration, and Harshness) performance has been an important measure when evaluating overall vehicle performance, product quality, and enhancing customers' loyalty to the product. The noise and vibration, while the engine is idling, has been brought particular attention to the drivers and passengers, because they encounter the operation conditions quite frequently without other masking noise sources: wind noise, road noise, and even powertrain radiated noise at higher speed driving. The specific noise, defined as 'CHIT' noise, has been identified as a potential customer issue, from the Pickup Truck with newly developed V8 powertrain. This paper describes the definition of the noise, identifying the potential sources, and noise radiation mechanisms, based on series of powertrain and vehicle test and verification processes. Then, based on the root-cause identified, the design change has been proposed and validated with several vehicles in order to have a complete satisfaction of the customer.