• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.457-460
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• 2000

The effect of code selection for a multicode DS/CDMA system is evaluated for a high deta rate transmission, The performance is evaluated in terms of bit error and outage probabilities. The multipath fading channel is modeled as a Nakagami-m distribution which has been known to be appropriate to model the multipath fading in urban as well as indoor channels. From simulation results, it is shown that the concatenated sequence of Walsh code and Gold sequence is most promising among many code selections. The considerations in this paper can be applied to the next-generation mobile communication systems such as IMT-2000 which requires high bit rate transmissions.

• Korean Management Science Review
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• v.16 no.1
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• pp.89-99
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• 1999

Combat fatigues are issued to military personnel with ready made clothes. Ready made combat fatigues should be fitted to various bodies of military personnel within given standard size. This paper develops a standard sizes selection method in order to increase the coverage rate and fitness for combat fatigues. The method utilizes a generalized learning vector quantization(GLVQ) algorithm that is one of cluster algorithm in neural networks techniques. The GLVQ moves the standard sizes from initial arbitrary sizes to next sizes in order to increase more coverage rate and fitness. Finally, when it cannot increase those, algorithm is terminated. The results of this method show more coverage rate and fitness than those of the other methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.1
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• pp.56-65
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• 1998

In this paper, experimental investigation of capillary tube performance for R-407C is performed. The experimental setup is made of real vapor-compression refrigerating system. In this study, mass flow rate is measured for capillary tubes of various diameter and length as inlet pressure and degree of subcooling are changed. These data are compared with the results of a numerical model. The mass flow rates of the numerical model are less than by 14% compared with the measured mass flow rates. It is found that mass flow rate and length for R-407c are less than those of R-22 under the same condition. Also based on this experimental study and the numerical model, a set of capillary tube selection charts for R-407C is constructed.

• Journal of the Korea Society of Computer and Information
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• v.22 no.5
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• pp.81-88
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• 2017

Solar-powered wireless sensor nodes can use extra energy to obtain additional data to increase the precision. However, if the amount of data sensed is increased indiscriminately, the overhead of relay nodes may increase, and their energy may be exhausted. In this paper, we introduce a sensing and compression rate selection scheme to increase the amount of data obtained while preventing energy exhaustion. In this scheme, the neighbor nodes of the sink node determine the limit of data to be transmitted according to the allocated energy and their descendant nodes, and the other nodes select a compression algorithm appropriate to the allocated energy and the limitation of data to be transmitted. A simulation result verifies that the proposed scheme gathers more data with a lower number of blackout nodes than other schemes. We also found that it adapts better to changes in node density and the amount of energy harvested.

• Korea Journal of Hospital Management
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• v.26 no.2
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• pp.17-26
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• 2021

Purposes: This study aims to identify factors affecting dental university hospitals' profitability and understand recent their business condition. Methodology: Data from 2016 to 2019 was collected from financial statement, public open data in 8 dental university hospitals. For the study, multiple regression test with stepwise selection was applied. Findings: First of all, 9 out of 19 independent variables were selected by stepwise selection. As a result of multiple regression test with selected independent variables and the dependent variable(operating profit margin ratio), the factors affecting hospitals' profitability were the number of dental unit chair, hospital location, debt ratio, total capital turnover ratio, employment cost rate, material cost rate, management expense rate, the number of patient per a dentist. Practical Implication: To improve dental university hospitals' profitability, hospitals specifically analysis and manage their cost such as employment, material and management cost and seek effectiveness by managing the proper number of patient per a dentist.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.681-693
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• 1995

A new set of capillary tube selection charts for R-22 is proposed. The set of charts takes into account of the roughness effect on the mass flow rate. For this purpose, a set of numerical model is developed and a series of experiments is conducted to verify the numerical model. A numerical model is used to calculated the mass flow rate for several sets of tube diameter, length, inlet pressures and degree of subcooling. The outlet of the tube is controlled to be at critical condition. The experimental flow rate is compared with calculated values. The calculated values are consistently less than the experimental ones except for the flow rate range below 40kg/hr. The deviation is within 10---. Based on the nunmerical model and results of experiments, the set of capillary tube selection charts for R-22 is constructed. The set of charts consists of standard capillary tube chart(L=2030mm, d=1.63mm, ${\varepsilon}=2.5{\mu}m$), non -standard flow factor(${\phi}_1$) chart, and non-standard roughness factor(${\phi}_2$) chart. The mass flow rate, flow factor, and the roughness factor are defined respectively as; $\dot{m}={\phi}_1{\phi}_2\dot{m}_{standard}\\{\phi}_1=\frac{\dot{m}(L,\;d,\;\varepsilon_{standard})}{\dot{m}_{standard}(L_{standard},\;d_{standard},\;{\varepsilon}_{standard})}\\{\phi}_2=\frac{\dot{m}(L_{standard},\;d_{standard},\;{\varepsilon})}{\dot{m}_{standard}(L_{standard},\;d_{standard},\;{\varepsilon}_{standard})}$.

• Archives of Plastic Surgery
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• v.34 no.5
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• pp.569-573
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• 2007

Purpose: The selection of the recipient vessels in breast reconstruction has a great influence on the surgical result and the shape of the reconstructed breast. We would like to introduce the criteria for the selection of recipient vessels in delayed reconstruction of the breast. Methods: We studied 56 patients with delayed breast reconstruction using free TRAM flaps from April 1994 to December 2006. The thoracodorsal and the ipsilateral internal mammary vessels were used as recipients in 25 patients each, the opposite internal mammary vessels in 3 patients, the thoracoacromial vessels in 2 patients, and the transverse cervical artery with the cephalic vein in 1 patient. The survival rate of the flaps, the vessel diameter, the length of the pedicles, and the convenience of vessel dissection were studied. Results: The diameter of the recipient vessel did not influence the anastomosis. The operation time, the survival rate of flap, the postoperative complications showed no significant difference according to the recipient vessel. Dissection of the thoracodorsal vessels was tedious due to scar formation from the prior operation. Dissection of the internal mammary vessels proved to be relatively easy, and the required length of the pedicle was shorter than any other site, but the need for removal of rib cartilage makes this procedure inconvenient. Conclusion: The first choice of the recipient vessel in immediate breast reconstruction is the thoracodorsal vessels, but in cases of delayed reconstruction the internal mammary vessels are favored as the first choice, because the thoracodorsal vessels have a high unusability rate. If the ipsilateral internal mammary vessels prove to be useless, the contralateral vessels can be used. The thoracoacromial vessels are useful, when the mastectomy scar is located in the upper portion. The transverse cervical artery and the cephalic vein can serve as the last resort, if all other vessels are unreliable.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.2
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• pp.193-217
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• 2019

Researchers have observed one student who had difficulty in formulating a division equation. In the context of determination of a unit rate problem based on one student's case and previous research, we tried to examine in detail how students expressed the division formula, how to select the dividend and the divisor, and how they learned about those. First, a questionnaire was developed to analyze student's reactions and applied to the research participants. Interviews were conducted to discover how the participants choose the dividends and divisors derived from their cognitive characteristics corresponding to their selection method. The research exposed that the majority of the participants had difficulty in deciding the dividends and divisors. Moreover, the research indicated information that teaching methods need to be reformed. Finally, we obtained suggestions to place emphasis on how to decide a dividend and a divisor, why they made such selection and what the equation means. We proposed a learning method for the research above.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.13-18
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• 2017

Farmers seek for high profitability by increasing the best use of land, and the selection of crops is the first and basic way to achieve their goals. When farmers select crops, the climate, price and productivity of crops are usually considered at the first stage. However, a crucial factor is to understand general characteristics of soils where the crops were grown, but many farmers are lacking in detailed knowledge about soils. The purpose of this study is to search and analyses factors based upon related soil and others in decision-making for the selection of crops. In result, the cultivated rate of the top 5 corps in the suitable areas for cultivation (SAC) is only 53 % which shows most farmers are plants their crops in unsuitable sites. To examine factors influencing on the selection of crops except for soils, surveys about their farm characteristic and Korea Soil Information System (KSIS) were conducted. The result of survey shows 20 % of farmers know KSIS. To increase that rate, there were many changes on soil's characteristic, and at the same time, climate conditions should be updated. It can be expected to increase the rate of farmers' utilization of KSIS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3884-3910
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• 2016

Intrusion Detection System (IDS) in general considers a big amount of data that are highly redundant and irrelevant. This trait causes slow instruction, assessment procedures, high resource consumption and poor detection rate. Due to their expensive computational requirements during both training and detection, IDSs are mostly ineffective for real-time anomaly detection. This paper proposes a dimensionality reduction technique that is able to enhance the performance of IDSs up to constant time O(1) based on the Principle Component Analysis (PCA). Furthermore, the present study offers a feature selection approach for identifying major components in real time. The PCA algorithm transforms high-dimensional feature vectors into a low-dimensional feature space, which is used to determine the optimum volume of factors. The proposed approach was assessed using HTTP packet payload of ISCX 2012 IDS and DARPA 1999 dataset. The experimental outcome demonstrated that our proposed anomaly detection achieved promising results with 97% detection rate with 1.2% false positive rate for ISCX 2012 dataset and 100% detection rate with 0.06% false positive rate for DARPA 1999 dataset. Our proposed anomaly detection also achieved comparable performance in terms of computational complexity when compared to three state-of-the-art anomaly detection systems.