• Journal of Korean Society of Transportation
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• 제35권5호
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• pp.447-457
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• 2017

This study aims to analyze the accidents of green mode bicycle. In pursuing the above, this study gave special emphasis on modeling the bicycle accidents reflecting the regional characteristics. The main results are as follows. First, the null hypotheses that the number of accident and ratio of serious injury and fatality (FSI) were the same over regions were rejected. Second, as the common variables, the number of bicycle was judged to have positive (+) impact to the accidents and the bicycle using ratio was inferred to increase the ratio of FSI. Third, the elderly population ratio among 3 factors which gave impact to the accidents of Si_A (city-county consolidation) was concluded to have the greatest elasticity. The developed area ratio between 2 factors in Si_B (city which is not consolidated) was, however, estimated to have the higher elasticity. Fourth, the number of car registration among 5 accident factors of Gun (county) was analyzed to have the greatest elasticity. Finally, the commuting trip ratio among 7 accident factors of Gu (district) was judged to have the greatest elasticity. This study can be expected to give some implications to regional policy-making related to bicycle.

• Journal of Korean Society of Water and Wastewater
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• 제31권5호
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• pp.459-469
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• 2017

A real scale leakage test facility was developed to study the leak signal characteristics of water supply pipelines, and then leak tests were carried out. The facility was designed to overcome the limited experimental circumstances of domestic water supply pipeline experimental facilities. The length of the pipeline, which was installed as a straight line, is 280m. Six pipes were installed on a 70m interval with different pipe material and diameters that are DCIP(D200, D150, D100, D80), PE(D75) and PVC(D75).The intensity of the leakage is adjusted by changing the size of the leak hole and the opening rate of ball valve. Various pressure conditions were simulated using a pressure reducing valve.To minimize external noise sources which, deteriorate the quality of measured leak signal, the facility was built at a quiet area, where traffic and water consumption by customers is relatively rare. In addition, the usage of electric equipment was minimized to block out noise and the facility was operated using manual mode. From the experimental results of measured leakage signal at the facility, it was found that the signal intensity weakened and the signal of high frequency band attenuated as the distance from the water leakage point increased.

• Journal of the Korean Society for Nondestructive Testing
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• 제30권4호
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• pp.359-366
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• 2010

For the application of Lamb wave to structural health monitoring(SHM), understanding its physical characteristic and interaction between Lamb wave and defect of the host structure is an important issue. In this study, reflected, transmitted and mode converted Lamb waves at discontinuity of a plate structure were simulated and the amplitude ratios are calculated theoretically using Modal decomposition method. The predicted results were verified comparing with finite element method(FEM) and experimental results simulating attached PZTs. The result shows that the theoretical prediction is close to the FEM and the experimental verification. Moreover, quantitative estimation method was suggested using amplitude ratio of Lamb wave at discontinuity.

• Journal of the Korean Society of Clothing and Textiles
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• 제27권9_10호
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• pp.1081-1092
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• 2003

The purpose of this study was to identify the current situation of textiles and apparel firms in the overseas markets and to examine the relationship between firms' characteristic(i.e., sales volume) and international marketing strategies. A random sample of 311 textiles and apparel firms were selected. The survey design method was used to test conceptual framework. Adjusted response rate was 33.4%(n=115). Descriptive analysis (i.e., frequency, percent) and $\chi$$^2$-test were used for data analysis. About the current situation of textiles and apparel firms in the overseas markets, the motivation for international market entry was highly found to expand their operation from domestic to international market, and most firms were found to be involved with OEMs(Original Equipment Manufacturers) as an entry mode for international market. China and US market were the most popular market among Korean textiles and apparel firms. Product differentiation strategy, pricing strategy based on manufacturing cost and buyer's offering price, place strategy using foreign buyers and participating a few international exhibition were frequently used among Korean textiles and apparel firms for international marketing. Among textile firms, sales volume was related to product strategies(product development), price strategy(buyer's offer) and place strategy(channel). Among apparel firms, product strategy(product labeling), price strategy(price satisfaction). The findings of this can be used when Korean textiles and apparel firms do strategic planning and evaluate the international marketing strategies. Also information and results of this study may assist policy makers to develop better ideas and strategies for textiles and apparel industry.

• Korean Journal of Ecology and Environment
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• 제41권2호
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• pp.247-263
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• 2008

A two-dimensional (2D) reservoir hydrodynamics and water quality model, CE-QUAL-W2, is employed to simulate the hydrothermal behavior and density current regime in Andong Reservoir. Observed data used for model forcing and calibration includes: surface water level, water temperature, dissolved oxygen and suspended solids concentration. The model was calibrated to the year of 2003 and verified with continuous run from 2000 till 2004. Without major adjustments, the model accurately simulated surface water levels including the events of large storm. Deep-water reservoirs, like Andong Reservoir, located in the Asian Monsoon region begin to stratify in summer and overturn in fall. This mixing pattern as well as the descending thermocline, onset and duration of stratification and timing of turnover phenomenon were well reproduced by the Andong Model. The temperature field and distinct thermocline are simulated to within $2^{\circ}C$ of observed data. The model performed well in simulating not only the dissolved oxygen profiles but also the metalimnetic dissolved minima phenomenon, a common1y occurring phenomenon in deep reservoirs of temperate regions. The Root Mean Square Error (RMSE) values of model calibration for surface water elevation, temperature and dissolved oxygen were 0.0095 m, $1.82^{\circ}C$, and $1.13\;mg\;L^{-1}$, respectively. The turbid storm runoff, during the summer monsoon, formed an intermediate layer of about 15 m thickness, moved along the metalimnion until being finally discharged from the dam. This mode of transport of density current, a common characteristic of various other large reservoirs in the Asian summer monsoon region, was well tracked by the model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제15권6호
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• pp.548-553
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• 2004

In this paper, single, two, and three-section microstrip directional couplers are implemented for realizing the high directivity characteristics. The achievement of the high directivity with microstrip configuration is carried out by the distributed capacitor to decrease the even and odd mode phase difference. Capacitive compensation is performed by gap coupling of open stub formed in sub-coupled line. Therefore, insertion loss and power handling capability are not affected by the gap coupling. The proposed structure is easy to fabricate and incorporate another microwave device due to the planner microstrip. We designed and fabricated single, two, and three-section directional coupler with 20 ㏈ coupling. In spite of microstrip structure, the capacitive compensation structure shows 30 ㏈, 27 ㏈, and 25 ㏈ of directivity in single, two, and three-section directional couplers, respectively.

• Journal of the Society of Naval Architects of Korea
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• 제32권2호
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• pp.93-102
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• 1995

A series of test was performed by measuring the failure strength and the failure mode of fiber reinforced composite laminates joint containing two holes in Series or Parallel. $[0^{\circ}/45^{\circ}/90^{\circ}/-45^{\circ}]_s$ laminate with W/d(Side distance ratio) 4.0 and E/d(Edge distance ratio) 3.0 has the full bearing strength and are preferable in case of the good efficiency in two series hole. Comparisons were made between testing results and predicting values of the FEM model. Good agreements were fecund between them except the case of $E/d=2{\sim}3$. In the case of $G_h{\geq}3.0d$ and $G_v{\geq}3.0d$ since the interaction coefficients between two parallel holes and between two series holes were small, holes can be treated as independent. The Acoustic Emission(AE) and SEM method were utilized to find out the initial defects, damage and the fracture mechanism.

• Proceedings of the KSR Conference
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1828-1838
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• 2009

This study will analyze what is favorable of urban structure in order to introduce new transit system like bi-modal tram. As a reasonable transport mode in a city, the bi-modal tram needs to be considered with respect to the space structural pattern and city growth process. The result of this study may provide the basic resource that helps transport decision makers to decide how to introduce bi-modal tram by considering the urban structural characteristics. Also, the results that analyzed a functional characteristic of a bi-modal tram with a effective urban polices will be informative for practical use.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2227-2232
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• 2009

Novel polythiol materials of urethane lens series for plastic optical lens were synthesized from polyol materials via thioisouronium of thiourea with c-HCl in refluxing aqueous solution, in which polythiol material was carried out from hydrolysis of thioisouronium by ammonia water. Their structure properties were identified by EA, EI-MS, FT-IR, $^1H\;and\;^{13}C$ NMR spectroscopies and TGA. Their ophthalmic lenses as polythiourethane material were prepared by thermal curing to an injected glass mold using the evenly solutions of diisocyanates series (TDI, XDI, HDI or IPDI) with polythiols. Polythiourethane shows that the strong stretching mode for SH group of polythiol disappeared in FT-IR spectra after thermosetting polymerization. Thermal deformation starting temperature of ophthalmic lenses was determined by TMA. Ophthalmic lenses made from characteristic polythiol and diisocyanate series have transparency, colorless and good impact strength, in which thermal resistance and impact strength of ophthalmic lenses were influenced by diisocyanate series. Physical properties of ophthalmic lens have contrast thermal resistance with impact strength. The property of thermal resistance and impact strength for respective ophthalmic lenses was examined by TMA and drop ball test.

• Korean Journal of Optics and Photonics
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• 제18권1호
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• pp.50-55
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• 2007

Using the Selective Area Growth (SAG) technology of Metal Organic Chemical Vapor Deposition (MOCVD), we successfully integrated an active device and passive devices on the same substrate. In other words, we integrated a Semiconductor Optical Amplifier (SOA) as an active device and an S-bend waveguide and a Multi Mode Interference (MMI) waveguide as passive devices. The SOA is successfully integrated with passive devices on the same substrate. The Cross-Gain Modulation (XGM) characteristic of the integrated SOA and the loss of an MMI and an S-bend waveguide were measured. Measured XGM characteristics of the SOA showed an extinction ratio of 8.82 dB. The total loss of the MMI and S-bend waveguide was 18 dB.