• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1483-1488
• /
• 2005

As the development of microprocessor technology, electric power steering(EPS) system which uses an electric motor came to use a few years ago. It can solve the problems associated with hydraulic power steering. The motor only operates when steering assistance is needed, so it can save fuel and can reduce weight and cost by eliminating hydraulic pump and piping. As one of performance criteria of EPS systems, the transmissibility from road wheel load to steering wheel torque is considered in this paper. The transmissibility can be studied by fixing the steering wheel and calculating the torque needed to hold the steering wheel from road wheel load. A proportion-plus-derivative control is needed for EPS systems to generate desired static torque boost and avoid transmissibility of fluctuation. A pure proportion control can' satisfy both requirements.

• Asian-Australasian Journal of Animal Sciences
• /
• v.11 no.1
• /
• pp.43-50
• /
• 1998

Three hundred and fifty-two growing pigs were utilized in three growth trials to investigate the effects of crystalline amino acid supplementation on growing pigs' growth performance and feed consumption. In Exp. 1, diets were formulated on the basis of digestible amino acids. Utilization of rapeseed meal plus cottonseed meal (R + C) in diet supported similar average daily gain (ADG), feed/gain (F/G) and cost per gain (p > 0.05) to group of soybean meal (SBM). In Exp. 2, 14% CP diets containing equal amount of cottonseed meal and rapeseed meal were formulated with the addition of threonine and/or tryptophan. Supplementation with threonine improved ADG and F/G (p < 0.05). Supplementation with only tryptophan made no benefits for ADG of growing pigs. In Exp. 3, diets with different threonine level were formulated. Increasing dietary threonine to 0.54% improved (p < 0.05) ADG and F/G compared to 0.45% dietary threonine. Increase in dietary threonine did not improve ADG (p > 0.05) but decreased F/G (p < 0.05) because of a decrease in average daily feed intake. Pigs fed diet with dietary threonine/lysine ratio of 67.5% supported optimum growth performance.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1998.10a
• /
• pp.36-39
• /
• 1998

It is very difficult for the large-scale retailers, who deal with tens of thousands of items, to price all the items dynamically reflecting all the constraints and policies. In spite of its importance, the prices are determined by human experts because the process of setting the prices of all the items is not established yet. To solve this problem, we adopt a mixed model that combines three typical pricing models: cost-plus model, competition-oriented model, and demand-oriented model. Since each model an be converted to a set of constraints in point and interval forms, solving the pricing problem with the three groups of models requires an algorithm which can solve the problem with weighted constraints of intervals and points. So we have devised an algorithm named “Point Determination Algorithm”. From the rules that represents tile models, the constraints are extracted to be solvable by tile Point Determination Algorithm. A prototype KAPA (Knowledge Assisted pricing Advisor) is developed with this idea using the expert system environment UNIK - a tool developed by KAIST. According to the experiment with 76 items in comparison with 53 human pricing experts we confirmed that the KAPA can perform highly consistent with human experts. This implies KAPA system is applicable to pricing millions of items dynamically.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.24 no.8
• /
• pp.612-620
• /
• 2012

High economic growth causes increase of the building energy consumption. The energy consumption for HVAC system accounts for 40~50% of the whole building consumption. The trend for building is large-scale and high-rise. Because of the trend, the energy consumption is becoming bigger than before. Nowadays, HVAC system design are recognized as the solution for a energy-saving. This paper is focused on the energy performance evaluation of central air-conditioning system(water-based) and system air-conditioning that were applied to the office building. The systems are modeled and simulated by using EnergyPlus Software 6.0. After the Simulation, annual cooling and heating energy consumption were calculated. It was found that the system air-conditioning can reduce the energy consumption approximately 55.24% annually compared with the central air-conditioning system(water-cooled). In addition, about 46.13% of annual operating costs can be reduced by use of system air-conditioning.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.04a
• /
• pp.83-90
• /
• 2009

As a series of 'Performance Assessment of Building Envelopes I: Double Skin Facade', three types (interior, exterior, mixed (int.&ext.)) of lightshelves and RetroLux were examined in terms of $CO_2$ emissions. It is shown that the exterior lightshelf could achieve the most energy savings (9.6-38.7%) in general office buildings due to blocking solar radiation before entering the indoor space. However, the interior lightshelf is the worst (1.4-5.2%) among three of them. The RetroLux has two components: (1) sun-reflector (first louver component), (2) light shelf for improving daylight induction (second louver component). Due to these two components, solar radiation from windows is filtered depending on seasonal variation (solar altitude). Therefore, the RetroLux can reduce 18.0-27.9% of annual energy consumption (both cooling and heating), and $552-3,290Won/m^2{\cdot}yr$ of operation cost is saved.

• KIEAE Journal
• /
• v.17 no.4
• /
• pp.75-81
• /
• 2017

Purpose: Most contemporary office buildings supply external views, a sense of openness and a sense of time to their occupants by adopting the curtain walls, which are equipped with an outer cover having large window area. As a result, the amount of radiation increases, adversely affecting cooling load during the summer in office buildings. Although solar radiation decreases heating load and reduces energy costs during the winter period, due to the characteristics of offices where occupants work largely during daytime, the cooling load is important compared to the heating. Therefore, diverse measures to resolve those trade-offs and annual energy cost have been investigated. Method: In this study, the annual thermal load was comparatively analyzed according to the slat angle of the venetian blind along with lighting control technique. Result: After selecting effective conditions, in order to resolve such issues, this study established automated control strategies of slat angle depending on the window-to-wall ratio and zone orientation, so that the findings of this study can be effectively generalized to other circumstances.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.3
• /
• pp.386-390
• /
• 2007

By use of a simple two-point extrapolation scheme estimating the correlation energies of the molecules along with the basis sets specifically targeted for extrapolation, we have shown that the MP2 basis set limit binding energies of large hydrogen-bonded complexes can be accurately predicted with relatively small amount of computational cost. The basis sets employed for computation and extrapolation consist of the smallest correlation consistent basis set cc-pVDZ and another basis set made of the cc-pVDZ set plus highest angular momentum polarization functions from the cc-pVTZ set, both of which were then augmented by diffuse functions centered on the heavy atoms except hydrogen in the complex. The correlation energy extrapolation formula takes the (X+1)-3 form with X corresponding to 2.0 for the cc-pVDZ set and 2.3 for the other basis set. The estimated MP2 basis set limit binding energies for water hexamer, hydrogen fluoride pentamer, alaninewater, phenol-water, and guanine-cytosine base pair complexes of nucleic acid by this method are 45.2(45.9), 36.1(37.5), 10.9(10.7), 7.1(6.9), and 27.6(27.7) kcal/mol, respectively, with the values in parentheses representing the reference basis set limit values. A comparison with the DFT results by B3LYP method clearly manifests the effectiveness and accuracy of this method in the study of large hydrogen-bonded complexes.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.7
• /
• pp.323-334
• /
• 2020

The quality of hospital services remains a concern of both the manager and the patient. The study aims to identify factors affecting outpatient satisfaction at private general hospitals in Ho Chi Minh City, establishing a scale for measuring them. Some 450 outpatients who were treated in five top private hospitals in Ho Chi Minh city (HCMC) in 2019 - An Sinh General Hospital, Hoan My General Hospital, Columbia Asia International Hospital, FV Hospital, and Vu Anh International General Hospital - were interviewed directly in the last quarter of 2019 to obtain the information. The SERVPERF model, plus the cost, together with the SPSS software, have been used to process information by Cronbach's alpha analysis, Exploratory Factor analysis, and linear regression analysis. The results show that there are five factors influencing outpatient satisfaction at private general hospitals in HCMC, in which four factors affects positively in the order of decreasing importance: treatment outcome, doctors and nurses' professional capacity, facilities and environment of the hospital, hospital care, and the treatment time factor affects negatively. The results of the study provide private hospital in HCMC managers with a number of suggestions to increase the level of hospital service quality, so that increase outpatients satisfaction.

• Journal of KIISE:Computing Practices and Letters
• /
• v.8 no.6
• /
• pp.717-726
• /
• 2002

In this study, we analyze hardware implementation schemes of the ARS(Advanced Encryption Standard-128) algorithm that has recently been selected as the standard cypher algorithm by NIST(National Institute of Standards and Technology) . The implementation schemes include the basic architecture, loop unrolling, inner-round pipelining, outer-round pipelining and resource sharing of the S-box. We used MaxPlus2 9.64 for VHDL design and simulations and FLEX10KE-family FPGAs produced by Altera Corp. for implementations. According to the results, the four-stage inner-round pipelining scheme shows the best performance vs. cost ratio, whereas the loop unrolling scheme shows the worst.

• Journal of the Optical Society of Korea
• /
• v.19 no.5
• /
• pp.514-520
• /
• 2015

This paper presents a novel shore-to-sea maritime data transmission system based on time-code diversity, using visible light in maritime environments to overcome the limitations of conventional maritime wireless communications. The proposed system is primarily comprised of existing LED-based lighthouses and maritime transceivers (marine beacons, buoys, etc.), and thus is considered cost-effective in terms of implementation. We first analyze maritime visible-light communications on the basis of the unique properties of a maritime environment, i.e. sea states (wave height, wind speed, etc.), plus atmospheric turbulence, using the Pierson-Moskowitz (PM) and JONSWAP (JS) spectrum models. It is found that the JS model outperforms the PM model, and that the coverage distance depends on the LED power and sea states. To combat maritime fading conditions that significantly degrade performance and coverage distance, we propose a time-code diversity (TCD) scheme in which the delayed versions of the original data are retransmitted using orthogonal Walsh codes. This TCD scheme is found to be superior, in that it offers three orders of magnitude in terms of BER performance, compared to a conventional (non-TCD) transmission scheme. The proposed scheme is robust and efficient in overcoming the effect of impairments present in maritime environments with a BER of approximately $10^{-5}$and a data rate of 100 Kbps at a distance of 1 km.