• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.04a
• /
• pp.319-326
• /
• 2000

The purpose of this study is to evaluate seismic performance of reinforced concrete pier columns in Seohae Ground Bridge. Since the bridge was designed before preparing the seismic design specification the bridge columns of hollow hexagonal section were designed and constructed with insufficient seismic reinforcement details such as longitudinal and transverse reinforcement lap-splices. In order to take the necessary measures to improve its seismic performance experimental study was performed by small-scale test for the bridge columns, From the quasi-static test for small-scale column specimens the lap-splices were not critical for overall behavior of the column if sufficient lap-splice-length was provided. The test results of failure mode effective stiffness ductility and equivalent viscous damping ratio are presented.

• Korean Journal of Biological Psychiatry
• /
• v.1 no.1
• /
• pp.7-16
• /
• 1994

I will try to serve as the basis for the development of a clinical therapeutic guideline of antipsychotic drugs. Knowing that many patients fail standard treatment recommendations, either because of insufficient efficacy or intolerance to adverse effects, led us to emphasize the importance of the guideline. The clinicians continually assimilate new information about recent advances, including : novel agents targeted to impact specific components of various neurotransmitter systems ; combination strategies ; alternative uses of existing agents ; and specialized requirements of a growing number of identified diagnostic subtypes. The cost to benefit ratio must always be considered when developing a therapeutic guideline.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2002.10a
• /
• pp.37-40
• /
• 2002

It is to show the problems of the existing techniques to estimate agricultural water demand and to suggest the new methods considering the water demand for non-irrigated area and decrease of water loss in canal. It is to suggest the methods to improve the techniques for estimating agricultural water demand and to analyze the water demand and supply according to the facilities capacity. Until now, the concept of per the unit used to estimate agriculture water demand is useful to estimate demand, but is insufficient to cope with the variations of conditions in future. And the paddy area of government is not realistic against a trend of decrease. Water demand decrease is caused by constructions of irrigation facilities as constructing of irrigation canal, but application loss ratio is fixed. Increase of the water demand owing to the increase of the yield per the unit area is also the actual condition which is not considered. The guide-line must contain these contents for a demand estimate.

• Journal of Distribution Research
• /
• v.1 no.2
• /
• pp.141-172
• /
• 1996

This study is to investigate global logistics strategies of Korean electronics companies. in terms of service parts. According to the survey, Korean electronics companies were pursuing multi-level global logistics network such as global, continental, national, regional and service center echelon for improving the efficiency of service parts global logistics. Especially there was a tendency of developing new continental distribution centers. And the companies were exploiting efficiency through inventory control by multi-level echelon, demand forecasting by the product life cycle and supply and service lead time management. But there were some insufficient factors for the efficiency of global logistics operation at the construction of worldwide real time logistics information system and pursuit of the efficiency on the whole network including subcontractors. For the future competitive advantage of the Korean electronics companies, the following are suggested: 1) the establishment of arranged logistics channel adjusting each company's global strategy, 2) the construction of worldwide real time logistics information system, 3) the reengineering of all logistics procedures such as order processing, shipping, inventory control, etc., 4) the enhancement of the ratio of the supply from the external companies and the internal manufacturing subsidiaries at each continent, 5) and the pursuit of operational internalization of external subcontractors.

• Journal of Power Electronics
• /
• v.18 no.2
• /
• pp.356-363
• /
• 2018

The combination of a buck converter and a forward converter can be considered to accomplish a high step-down non-isolated converter. To decrease the insufficient step-down ratio of a regular buck converter and to distribute switch voltage stress, a forward-integrated buck (FIB) converter is proposed in this paper. The proposed interleaved DC-DC converter provides an additional step-down gain with the help of a forward converter. In addition to its simple structure, the transformer flux reset problem is solved and an additional magnetic core reset winding is not required. The operational principle and an analysis of the proposed FIB converter are presented and verified by experimental results obtained with a 240 W, 150 V/24 V prototype.

• 한국생물공학회:학술대회논문집
• /
• 2000.11a
• /
• pp.553-556
• /
• 2000

Possibility of biological nitrogen treatment was tested in wastewaters with low C/N ratio. Chlorella kessleri was inoculated at $10^6\;cell/mL$ of initial density in two different artificial wastewaters: one that contained glucose for organic carbon source and the other without carbon source. Nitrate could be successfully reduced below 10 mg $NO_3/mL$ from initial nitrate concentration of 560 mg $NO_3/mL$ in 10 days even in the wastewater without carbon source, This 98% removal of nitrate without extra organic carbon source lights up the future of biological wastewater treatment, where the insufficient ability of nitrogen removal is a major problem.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.11
• /
• pp.2923-2931
• /
• 1996

In this paper, the symbol error probability for orthogonal frequency division multiplexing (OFDM) in the multipath fading environment is obtained analytically. In the analysis, OFDM signals with and without the guard interval are considered, and the two-ray fading model is used for the multi-path fading channel. From the analysis results, it is found that the adjacent subchannel interfernce increases the symbol error rate when the guard interval is not employed or shorter than the length of the delay. It is also shown that the adjacent subchannel interference is a Gaussian random variable and its variance depends on the subchannel location and the number of subchannels. Finally, it is found that the variance of the subchannel interference also increases as the power of the signal increases for the OFDM with insufficient guard interval, yieldin an irreducible error at high signal to noise ratio.

• Journal of the Korean Institute of Educational Facilities
• /
• v.5 no.3
• /
• pp.91-97
• /
• 1998

The purpose of this study is to investigate elementary school landscaping. The landscaping has intrinsic value for educational purpose as well as an open space resource in urban area. Four elementary schools in Taegu were surveyed and analyzed to identify the ratio of greenery, green volume and its maintenance. The result can be summarized as follows: 1. While 58 species of trees were quoted all over the text book, 17 to 52 species were found in each school and only few species were always dominant in each school. 2. The greenery and green volume were insufficient in terms of quantity and inadequate in placement, and there were differences in landscaping quality and quantity between schools. However the differences were not associated with the age of schools. 3. Functional implementations of landscaping technique(for example, environmental control) were needed for future landscaping of elementary schools.

• Tribology and Lubricants
• /
• v.22 no.1
• /
• pp.40-46
• /
• 2006

This paper presents the influence coefficient method to predict the deflection of bump foil precisely in the sub-structure of AFB(air foil bearing). Heshmat has introduced the simple compliance model to calculate the deflection of bump foil. But this approach can not consider the deflection of bump foil at the edge of AFB, so elasto-hydrodynamic model is insufficient to analyze in case that the eccentricity ratio is greater than 1. Peng has used the average pressure and film thickness, but this approach is not also a realistic model. Influence coefficients of a bump is calculated by finite element method, and introduced in bump deflection equations of the performance analysis of air foil bearing. The effects of the influence coefficient on the bearing performance is discussed in detail for appropriate foil design.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.505-511
• /
• 2003

Experimental investigation was conducted into the flexure/shear-critical behavior of earthquake-damaged reinforced concrete columns with lap splicing of longitudinal reinforcement in the plastic hinge region. Six test specimens in the aspect ratio of 2,5 were made with test parameters: confinement ratios, lap splices, and retrofitting FRP materials. They were damaged under series of artificial earthquakes of which magnitude could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under a constant axial load, P=$0.1f_{ck}A_g. Residual seismic performance of damaged columns was evaluated and compared to that of the corresponding original columns. Test results show that RC bridge piers with lap-spliced longitudinal steels in the plastic hinge region appeared to fail at low ductility. This was due to the debonding of the lap splice, which resulted from insufficient development of the longitudinal steels. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region indicated significant improvement both in flexural strength and displacement ductility, and strain energy ductility.