• Journal of Welding and Joining
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• v.20 no.6
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• pp.809-815
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• 2002

Metallurgical behavior of laser welded cold rolled low carbon steel was investigated. Welding was performed with CW Nd:YAG laser system. Applied laser power, travel speed and nitrogen blowing pressure were 720W CW, 17mm/s and 196kPa, respectively. According to the test results, many carbide particles were observed on the base metal surface that was polished and etched with nital solution. The carbide particles at the welding heat affected zone were thought to be dissolved during welding process. Microstructural inspection revealed that dissolved carbide particles formed mixed phase of very fine martensite and bainite. Test results also demonstrated that the hardness of matrix remained constant value of around 160Hv over the welding heat affected zone. Dissolved carbide particles, however, showed higher average hardness values of around 276Hv near the fusion boundary and 700Hv at the welding heat affected zone of 0.4mm apart from the fusion line. It was considered that care should be given to minimize the test error when measuring the hardness value since many of the dissolved particles were so small that it was not easy to aim the indentor of the testing machine just on the objects.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.113-120
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• 2013

This paper proposes a design optimization approach for core of solenoid actuators by combining optimization techniques with the finite element method (FEM). A solenoid is an important element part which hydraulically controls a transmission system, etc. The demanded feature of the solenoid is that it performs an electromagnetic force output being constant regardless of the stroke and being proportional to coil current. The plunger compresses a spring with a minimum force of 12 N over an 1.7 mm travel. The orthogonal array, analysis of variance (ANOVA) techniques and response surface optimization, are employed to determine the main effects and their optimal design variables. The methodology is demonstrated as a optimization tool for the core design of a solenoid actuator.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.69-76
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• 2007

This study was conducted to evaluate the sideways overturning stability of side loaded mini-forwarder. The model of a prototype was developed using a 3D CAD modeler and the performance was experimentally validated. The prototype model was run on the multibody dynamic analysis program, RecurDyn 6.0, to simulate motions when the model traversed over a circular bump on a inclined ground surface. The simulation was performed at a constant forward speed of 1.85 km/h under the loaded and unloaded conditions. The forward direction was also controlled to vary from 0 to 360 degrees with an increment of 10 degrees. Results of the simulation showed safe regions in which the mini forwarder could travel safely in terms of direction and slope of the ground. Even when the mini-forwarder was loaded by 20 logs of 3.6 m long and 12 cm diameter, it traveled safely within the ground slopes of 1 to 45 degrees by directions.

• Human Ecology Research
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• v.53 no.4
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• pp.375-390
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• 2015

This study was designed to understand the residential experience of Korean women living in tropical country. For qualitative research, interviewees were selected by snowball sampling among Korean women living in Malaysia for over 20 years. The selection criteria for interviewees included husband's nationality, occupational experience, future living plan, frequency of travel to Korea. In-depth group and individual interviews were conducted from August 23 to October 7 2014. Subsequently (1) interviewees' general residential experiences in Malaysia were summarized, (2) interviewee's identity and lifestyle with housing pathways approach were clarified, (3) interviewees' residential experiences in 5 issues, reciprocity in residential area, intention of environmental change, meaning of housing and interaction, housing adaptation, and residential satisfaction/dissatisfaction were prescribed and interpreted. In conclusion, the reflection of interviewees' experiences in tropical country, suggested variations of housing structure type within a residential complex, air well and pocket by setback in building block for improving ventilation and noise prevention from neighbors, and ceiling fans in the house were suggested for the upcoming subtropical climate in Korea. Full option and minus options were also suggested for the presale market to reduce before occupancy remodeling needs. The research results implies valuable suggestions for a multicultural society, ecological housing and stronger communities.

• Journal of Veterinary Clinics
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• v.37 no.4
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• pp.223-226
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• 2020

Cytauxzoonosis is caused by Cytauxzoon felis (C. felis) in wild and domestic cats. However, cytauxzoonosis is uncommon in Asia. Additionally, clinical reports of C. felis infection along with associated complications are rare. A seven-year-old neutered male Maine Coon cat was presented with acute dyspnea and lethargy despite the absence of a history of overseas travel. Mild regenerative anemia and autoagglutination were detected in hematological investigations. The parasitic and viral PCR assays revealed infection with C. felis and feline immunodeficiency virus (FIV). Thoracic radiographs showed pleural effusion with secondary bacterial infection. Ultimately, a diagnosis of infection-induced secondary immune-mediated hemolytic anemia (IMHA) and pyothorax was established. The cat was treated with a combination of atovaquone, prednisolone, and cyclosporine over 6 months and the final treatment was completed 8 months after initiation of therapy. This is the first report of its kind demonstrating successful management of feline IMHA and fatal pyothorax induced by FIV and C. felis in South Korea.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.377-381
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• 2006

A seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. General indicator of gas hydrate in seismic data is commonly inferred from the BSR(Bottom Simulating Reflector) that occurred parallel to the sea floor, amplitude decrease at the top of the BSR, amplitude blanking at the bottom of the BSR, decrease of the interval velocity and the reflection phase reversal at the BSR. In this paper we had analyzed optimum parameters of the field data to detect the 9as hydrate. Shot delay correction is applied 95ms, spherical divergence correction is applied velocity library 3, bandpass filter is applied 25-30-115-120Hz deconvolution operator length is applied 60ms, lag is 6ms and accurate velocity analysis NMO correction, stack is performed. Geobit 2.11.0 developed by the KIGAM was used for all data processing. Processing results say that the BSR occurred parallel to the sea floor were shown at 3,150m/s of two way travel time from the sea floor through shot point 5,000-5,610, and identified the interval velocity decrease around BSR and the reflection phase reversal corresponding to the reflection at the sea floor.

• Laser Solutions
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• v.18 no.2
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• pp.1-4
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• 2015

This study is related to the surface hardening treatment to spheroidal graphite cast iron for die by using high power diode laser. Laser device used in this experiment is capable of real-time laser power control. This is because the infrared temperature sensor (two color pyrometer) attached to the optical system measures the surface temperature of specimen and adjusts the laser power in real time. The surface treatment was carried out with the change of heat treatment temperature at the beam travel speed 3 mm/sec. Hardened width and depth was measured and hardened zone was analyzed by micro vickers hardness test in order to research the optimum condition of heat treatment. The changes in microstructure of the hardened zone also was examined. As a result of hardness measurement and observations on microstructure of hardened zone, hardness increased over three times as compared with base metal because the martensite was formed on the matrix structure.

• Journal of the Korea Society for Simulation
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• v.10 no.3
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• pp.47-58
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• 2001

Evaluation of Freeway Congestion Management Using Mesoscopic Traffic Simulator A mesoscopic simulation study to measure the effects of trip generation caused by rampant expansion of residential area around the Kyungbu corridor has been conducted. Some alternatives, which seem to be judgememtally plausible and technically feasible to mitigate such congestion, have been carefully examined and evaluated by the simulation model called INTEGRATION. Alternatives are mostly network improvements. Banpo IC dedicated ramp construction (A1), Seocho IC TSM based weaving elimination (A2), dedicated local and express separation over Seocho-Yangjae segment (A3), Heonleung IC (A4) and Daewang If installations (A5), Pangyo IC improvement (A6), Baikhyun IC (A7) and Dongbaek IC installations (A8) along with Shingal-Pangyo segment capacity addition (A9). The most capital intensive ones are A9, A5, and A4 in that order. A1, A6, A7, and A8 are short in distance but they are also capital intensive and need some construction periods. The least capital driven alternatives are h2 and A3, the h2 is easier to do, but A3 needs traffic diversion scheme during construction. The A1, A7, and A8 have been identified cost effective in terms of speed increase and travel time saving. Along with these results, some limitations and future research agenda regarding simulation have also been presented.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.437-443
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• 2009

Generally speaking, the uniqueness of Korea for the high-speed railway rolling-stock is mainly perceived through the travel over the high-speed electric railway by passengers, which consists of the organization of space in the coach and its interior design. For such purpose, it is necessary to build a series of independent cultures with high-speed railway i.e. to have the development of design technologies oriented to harmonizing human beings, their society and culture with the systematic integration of production technologies to support the culture and its substructure foundation which constitute the frame of superstructure in the society, by defining the relationships with travelers on the high-speed railway as well as enhancing the comfort and convenience of high-speed railway through drawing up the development of links with the systematic integration among lines of technologies on the basis of 'User Train Interface. This thesis aims at introducing the study carried out to build the evaluation standards of performance outputs for 'HEMU-400X rolling-stock Design' derived from the performance for the first year in the research 'Development of Technologies for the Next-Generation High-Speed Railway' as part of "Development Project for the Future Railway Technologies" from 2007.

• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.588-595
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• 2008

This study is carried out for understanding mode choice behavior of shippers and introducing ideal mode share between rail and truck in Korea. The model type is individual behavioral model and the input data type is stated preference (SP) data. SP data was prepared by design of experiments. The explanatory variables in models are transport time, transport cost and service level. The research result shows that it is more effective to reduce transport cost rather than to implement other strategies. For container, reducing transport cost and transport time and increasing service level simultaneously can strengthen the competitiveness of rail over truck transportation. On the other hand, for bulk freight such as cement and steel, it is better to reduce the transport cost than to do other attributes.