• Journal of the Korean Solar Energy Society
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• v.35 no.5
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• pp.39-48
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• 2015

In this study, the solar chimney, one of the passive solar systems, is proposed as a method to improve the thermal environment of northern zones in buildings. As this well-known system has rarely been used in building projects, an adequate application of the system is proposed in this paper: the solar chimney system is designed to meet the required ventilation rate and consequently to reduce the ventilation load in the northern part of a building. To investigate such a possibility, a numerical model for the system is developed, and results of numerical tests are used for energy simulations. The results were taken into account for test simulations in EnergyPlus. As a result, approximately 75% of the volumetric ventilation rate required in the north zone could be supplied with the air volume acquired through the system and the monthly mean load was reduced by 29.5%, from 1.584 kWh to 1.117 kWh. The analyses of hourly mean heating and ventilation load over the heating period indicated that the system was very effective at around 13:00. Results show that 33% reduction in the ventilation load and 17% in the heating load for the north zone could be acquired through this system.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.58-68
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• 2009

Low impact development (LID) technique is relatively new concept to reduce surface runoff and pollutant loading from land cover by attempting to match predevelopment condition with various integrated management practices (IMPs). In this study, computational model for designing and evaluating LID, named LIDMOD, was developed based on SCS-CN method and applied at Andong bus terminal to evaluate LID applicapability and design retention/detention area for volume or peak flow control. LIDMOD simulated with 21 years simulation period that yearly surface runoff by post-development without LID was significantly higher than that with LID showing about 2.8 times and LID could reduce efficiently yearly surface runoff with 75% reduction of increased runoff by conventional post development. LIDMOD designed detention area for volume/peak flow control with 20.2% of total area by hybrid design. LID can also efficiently reduce pollutant load from land cover. Pollutant loads from post-development without LID was much higher than those from pre-development with showing 37 times for BOD, 2 times for TN, and 9 times for TP. Pollutant loads from post-development with LID represented about 57% of those without LID. Increasing groundwater recharge reducing cooling and heating fee, creating green refuge at building area can be considered as additional benefits of LID. At the point of reducing runoff and pollutant load, LID might be important technique for Korean TMDL and LIDMOD can be useful tool to calculate unit load for the case of LID application.

• Journal of Korea Water Resources Association
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• v.42 no.1
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• pp.1-8
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• 2009

In this study, based on the major activities which might have affected the ecological system of the Geum River, a conceptual model was proposed to guide scenario development for the eco-hydrological river evaluation. Also, an analysis method employing a set of models consisting, with other supporting programs, of KModSim for watershed network analysis and RAP for ecosystem analysis was developed for eco-hydrological river assessment. Then, hydrological analyses with various scenarios were conducted to examine the flow regime changes expected from the construction and operation of the Youngdam Multipurpose Dam (YMD) and Daecheong Multipurpose Dam (DMD) in the Geum River basin. The results indicated that the "Percentile 10" values for 10% exceeding time were decreased by 20.5% and 8.0% at Sutong downstream of YMD and Gongju downstream of DMD, respectively, while "Percentile 90" values for 90% exceeding time were increased by 56.3% and 340.8% at Sutong and Gongju, respectively, resulting in the reduction of the high flow variability typical for unregulated rivers in Korea. The results of eco-hydrological analyses will be presented in the following papers.

• Journal of Hydrogen and New Energy
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• v.22 no.2
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• pp.129-138
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• 2011

Performance changes of an anode-supported tubular SOFC including current collectors are analyzed at different current collecting methods using numerical simulation. From the two dimensional numerical model of the solid oxide fuel cell with nickel felts as anodic current collectors and silver wires as cathodic ones, the performance curves and the distributions of temperature, concentration, current density are obtained. Also, the voltage loss of the cell is divided into three parts: activation loss, concentration loss and ohmic loss. The results show that the performance change of the cell is dominantly influenced by the ohmic loss. Although the temperature and concentration distributions are different, the total activation loss and concentration loss are nearly same. And the ohmic loss is divided into each parts of the cell components. The ohmic loss of the anodic current collectorreaches about 60~80% of the cell's total ohmic loss. Therefore, the reduction of the ohmic loss of the anodic current collector is very important for stack power enhancement. It is also recommended that the load should be connected to the both ends of the anodic current collector.

• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.75-84
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• 2016

The purpose of this study was to investigate the performance of solid reinforced concrete columns with triangular reinforcement details. The proposed reinforcement details has economic feasibility and rationality and makes construction periods shorter. A model of solid reinforced concrete columns with triangular reinforcement details was tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. The used numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated. As a result, proposed triangular reinforcement details for material quantity reduction was superior to existing reinforcement details in terms of required performance.

• The Journal of Internal Korean Medicine
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• v.38 no.4
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• pp.468-478
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• 2017

Objectives: This study investigated the effects of Douchi Hataedock on Th2-skewed conditions to control allergic rhinitis. Methods: NC/Nga mice were divided into three groups: 10 mice were assigned to the control group (CTRL; no treatment), 10 mice to allergic rhinitis-induced (ARE) without treatment group, and 10 mice to the allergic rhinitis-induced (FGT) after Douchi Hataedock treatment group. The 3-week-old mice of the FGT group were given one 10 mg/kg dose of Douchi Hataedock extract and resensitized to allergic antigens at weeks four, five, and six. Allergic rhinitis was induced primarily in mice nasal cavities for five days after one week of final sensitization. The second induction used the same method one week after the first induction was completed. After one week, the nasal mucosal tissues of each group were observed. Immunohistochemical staining for IL-4, STAT6, CD40, $Fc{\varepsilon}RI$, substance P, MMP-9, $NF-{\kappa}B$ p65, p-IkB, and iNOS in the nasal mucosa was also performed. Results: The FGT group had less respiratory epithelial damage and less mucin secretion in goblet cells than the ARE group and showed a 62% decrease in IL-4, 85% decrease in STAT6, 71% decrease in CD40, 69% decrease in $Fc{\varepsilon}RI$, 43% decrease in substance P, 49% decrease in MMP-9, 43% decrease in NF-kB p65, 38% decrease in p-IkB, and 73% decrease in iNOS compared to the ARE group. Conclusions: Douchi Hataedock lessens inflammation in epithelial and goblet cells and reduces inflammatory mediator secretion in a mouse allergic rhinitis model.

• Korean Journal of Adult Nursing
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• v.15 no.4
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• pp.650-659
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• 2003

Purpose: The purpose of this study was to identify predictors of depression and quality of life among older adults with osteoarthritis. The predictors included in the model were the client's characteristics(age, pain, disease duration, ADLs), personal resources(hardiness, self-care agency and family support), and depression. Method: 150 subjects who were older than 65 years and had diagnosis of osteoarthritis participated in the study. To answer the research questions, descriptive analysis, Pearson correlation, and hierarchical multiple regression were utilized using SPSS WIN program. Result: Older adults who were younger and had lower levels of pain and dependency on ADLs, and higher levels of self care agency and hardiness reported lower levels of depression($R^2=0.517$). Older adults who had lower levels of depression, pain, and dependency on ADLs, higher levels of family support and hardiness, and who are younger reported higher levels of quality of life($R^2=0.084$). Conclusion: Based on the findings of this study, development of nursing intervention program including pain reduction, enhancing ADL abilities and personal resources (hardiness, family support) can be suggested. Further study is needed to increase the ability of generalization of the study findings to the broader population.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.55-65
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• 1998

In industrial fields, RTP(rapid thermal processing) system is widely used for improving the oxidation and the annealing in semiconductor manufacturing process. The main control factors are temperature control of wafer and uniformity in the wafer. In this paper, we propose an $H^{\infty}$ controller design of RTP system satisfying robust stability and performance using weighted mixed sensitivity miniimization and loop shaping technique. And we need reduction technique because of the difficulty of implementation with the obtained high order controller for original model and reduced models, namely, Hankel, square-root balanced, and Schur balanced methods. An example is proposed to show the validity of the proposed method.

• Plant Journal
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• v.4 no.3
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• pp.54-59
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• 2008

The resonance of boiler is caused by exciting force in the gas path and it generates the vibration by the harmony of boiler's dimensional factor. According to trending toward the boiler of increasing capacity and a bigger size, it has a problem of the vibration at back-pass heating surfaces. We can predict such vibrations as comparison between vortex frequency and gas column's natural frequency. We can't rely on the method for the past decades because of changing parameters, such as an allowable error, gas temperature, gas velocity, Strouhal number. We can reduce the vibration to use the seasoning effect and change the operating condition in coal fired boiler but it's not essential solution. When the vibration occurred in the model boiler, we must measures the acoustic pressure and frequency of places for considering the means. So far, we confirmed the problem from field measures and theoretical analysis about the acoustic vibration of boiler. We installed anti-acoustic baffle in a existing boiler to change the acoustic natural frequency at the cavity, which results in reducing the acoustic vibration. The first, we prove that the acoustic resonance is caused by harmonizing vortex shedding frequency of tube heat surface with acoustic natural frequency of cavity in the range of 650~750 MW loads. The second, the acoustic resonance at the back-pass heating surface has the third order of acoustic natural frequency at the second economizer. We install five anti-acoustic baffles at the second economizer to reducing the resonance. We confirm considerably reducing the acoustic vibration of boiler during the commercial boiler.

• The Korean Journal of Applied Statistics
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• v.29 no.6
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• pp.1095-1106
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• 2016

The quantile regression method proposed by Koenker et al. (1978) focuses on conditional quantiles given by independent variables, and analyzes the relationship between response variable and independent variables at the given quantile. Considering the linear programming used for the estimation of quantile regression coefficients, the model fitting job might be difficult when large data are introduced for analysis. Therefore, dimension reduction (or variable selection) could be a good solution for the quantile regression of large data sets. Regression tree methods are applied to a variable selection for quantile regression in this paper. Real data of Korea Baseball Organization (KBO) players are analyzed following the variable selection approach based on the regression tree. Analysis result shows that a few important variables are selected, which are also meaningful for the given quantiles of salary data of the baseball players.