• Fire Science and Engineering
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• v.29 no.5
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• pp.29-33
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• 2015

In this study, the relations of flow rate, discharging distance and droplet size are measured in accordance with the nozzle shape. The dual type nozzles of LPN142 and LPN148, which have identical core diameter (6.0 mm) and the different radial injection angles (${\theta}_2=142^{\circ}$ and $148^{\circ}$), are manufactured. The distribution diameters with discharging distance are quantified by UL2167 test standard. The relations between discharging angle and droplet sizes, which are measured by the method of Helium-Neon laser equipment, are obtained by the empirical correlation as working pressure increase. Moreover, the extinction coefficient, which is major parameter of the radiative transport equation (RTE) is analyzed with variable droplet sizes. Thus, it is possible to opt the nozzle's shape by analyzing the relations of working pressure, spray distance, droplet size and fire characteristics at minimum allowable flow rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.859-866
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• 2010

This study examined the economics of a solar water heating system for an office building using life cycle cost (LCC) optimization simulations. The numerical simulations were conducted with TRNSYS and GenOpt employing the Hooke-Jeeves algorithm. The solar collector area, slope, mass flow rate per collector area and storage tank volume were selected as the main design parameters of the solar water heating system. The LCC optimization simulations of the system were carried out for cases where water temperature was $60^{\circ}C$ and $50^{\circ}C$. The results showed that for water temperature at $60^{\circ}C$ and $50^{\circ}C$ the collector area could be decreased by 17% and 28%, storage tank volume could be decreased by 49% and 54%, and mass flow rate per collector area increased by 5% and 9% respectively compared to a non-optimized system. The LCC of the system was reduced by 4% for $60^{\circ}C$ and 7% for $50^{\circ}C$. The initial installation cost of the system was reduced by 24% for $60^{\circ}C$ and 34% for $50^{\circ}C$. However, the operating cost of the system increased by 16% for $60^{\circ}C$ and 36% for $50^{\circ}C$ compared to a traditional solar water heating system.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.415-422
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• 1994

Recent new town construction project proouced large numbers of apartment houses using precast concrete (P. C.) panels. l'bst construction companies involved in this project put their management focus on to the individual control of P.C. panel producing plants and the job sites. Little attention was paid to the integrated management of the production. transportation. and im;tallation of P. C. panels. Numerous job site delays experienced in the new town project were largely based on the poor coordination between these three key disciplines of the P. C. apartment construction. This stlldy was initiated with an .intention to improve coordination between these disciplines. Activities of these disciplines were identified and related data were gathered. This was performed through the interv:iews with the personnel involved in P. C. constructlon and through the analy::;is of the related documents and publications. Based on this information. the authors are nolol developing a model IoIhich will provide a foundation for opt:iJnal.ly coorc.inated control of the proouction. transportation, and installation of P. C. panels for apartment construction. In this paper. the authors briefly present intermediate results of this study.

• Journal of Labour Economics
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• v.26 no.1
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• pp.23-52
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• 2003

This study focus on unemployment and nonparticipation of youth. By dividing youth nonparticipants into 'house work and child care', 'studying and training', 'the others' categories, we estimate the potential wages with selectivity bias model and analyse the factors of choosing unemployment or nonparticipation with multinomial logit model. The differences between the potential market wage and the desired wage of the groups of 'studying and training', 'the others' in the nonparticipants are greater than those of the unemployment group. In the case of the man and lower age, and low schooling the differences of potential and desire wage are larger than woman and higher age, and high schooling. In the choice of unemployment and nonparticipation, man and higher age, and householder, and holder of qualification are not likely to opt nonparticipation. The experience of job lower the rate of probability to choose employment, but raise the rate of probability to choose unemployment and nonparticipation. These results mean that the quality of youth employment is very inferior.

• Journal of Chest Surgery
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• v.50 no.4
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• pp.247-254
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• 2017

Background: Hybrid coronary revascularization (HCR) was developed to combine the advantages of coronary artery bypass graft (CABG) with percutaneous coronary intervention (PCI). However, it is still controversial whether it is more optimal to perform CABG or PCI first. The purpose of this study was to compare the clinical outcomes of these 2 approaches. Methods: Eighty patients who underwent HCR from May 2010 to December 2015 were enrolled in this retrospective analysis. The CABG-first group comprised 12 patients and the PCI-first group comprised 68 patients. Outcomes of interest included in-hospital perioperative factors, major adverse cardiac and cerebrovascular events (MACCEs), and the incidence of repeated revascularization, especially for the target vessel lesion. Results: No significant difference was found in the amount of postoperative bleeding (p=0.239). The incidence of MACCEs was similar between the CABG-first and PCI-first groups (1 of 12 [8.3%] vs. 5 of 68 [7.4%], p>0.999). Repeated revascularization was performed on 3 patients (25%) in the CABG-first and 9 patients (13.2%) in the PCI-first group (p=0.376). Conclusion: There were no significant differences in postoperative and medium-term outcomes between the CABG-first and PCI-first groups. Based on these results, it can be inferred that it is safe to opt for either CABG or PCI as the primary procedure in 2-stage HCR.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.432-439
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• 2013

This study was performed to assess the current stock condition of elkhorn sculpin along the Uljin area in the East Sea of Korea. To assess the state of the stock, yield-per-recruit (YPR) and spawning biomass-perrecruit (SBPR) analyses were performed. Estimates of $F_{max}$ and $F_{0.1}$ were 2.10/year and 0.48/year, respectively, and those of $F_{35%}$ and $F_{40%}$ were 0.66/year and 0.54/year, respectively. Current fishing mortality was estimated at 0.63/year and the current age at first capture was 2.41years. $F_{40%}$ was set as the target reference point of the stock. SBPR at $F_{40%}$ and current SBPR were estimated to be 41.85g and 37.77g, respectively. Estimated FOTY which is the fishing mortality for the overfished threshold yield was 0.49/year. The ratio of SBPR/$SBPR_{MSY}$ was calculated as 0.90 and that of $F/F_{OTY}$ was 1.05. The ratio of $t_c/t_{c\;opt}$ was calculated as 1.15 and that of $F/F_{OTY}$ was 1.17. Therefore, the current stock condition of elkhorn sculpin along the Uljin area of Korea has not been overfished, however, it indicates that a light overfishing is going on this stock.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.428-433
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• 2009

Dissolved oxygen is considered as one of the important water-quality constituents in streams from one century ago and fishes perish in low dissolved oxygen concentration. Environmental scientists and engineers have introduced the deterministic model to estimate dissolved oxygen concentration of streams and recommended the use of the Delta Method (DM), Approximate Delta Method (ADM), Extreme Value Method (EVM) and Optimization Method (OPT) which can be applied in no spatial variation of dissolved oxygen. The diurnal or annual variation of dissolved oxygen is mainly determined from the parameters such as reaeration rate, 1st production rate and respiration rate which are related to dissolved oxygen. Each method was briefly introduced and applied to two sampling sites of Anseong Stream watershed in this paper. The limitation, advantages and disadvantages of each method were reviewed and analyzed after running the each method. From these analyses, the benefit-cost approach to estimate dissolved oxygen effectively in streams was recommended.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7669-7674
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• 2013

Background: The hypothesis that patients who primarily progress on two consecutive chemotherapy regimens without evidence of clinical benefit may opt for supportive care was investigated. The purpose was to determine the quality of life in recurrent ovarian cancer patients choosing to receive salvage chemotherapy in addition to supportive care or palliative care alone. A secondary objective was to evaluate factors that affect quality of life in ovarian cancer patients. Materials and Methods: A descriptive study was conducted in patients who had histological confirmed epithelial ovarian cancer and failed to respond to at least one regimen of chemotherapy, coming for treatment at the King Chulalongkorn Memorial Hospital in Bangkok, Thailand over a six-month period from August 2012-March 2013. Each patient was asked to complete the FACT-G and a general personal questionnaire. The median quality of life score was analyzed. The Mann Whitney U Test was used to compare the difference between salvage chemotherapy and palliative care groups, and the Kruskal Wallis was used to evaluate other variables. Results: Thirty-eight ovarian cancer patients were identified who failed to respond to chemotherapy. Of the 38, 30 chose salvage chemotherapy and eight palliative care for further treatment. By histology the carcimnomas were predominantly endometrioid subtype and poorly differentiated. The majority of patients in this study had FIGO stage III, and ECOG status 0-1. The median quality of life score was 76.3 (35.8-94.0), with no significant differences between the groups. Factors associated with the quality of life were the ECOG score and number of chemotherapeutic courses. Conclusions: In the setting of refractory or recurrent epithelial ovarian cancer, patients who receive salvage chemotherapy have comparable quality of life scores with patients treated with palliative care alone, providing a contrast with previous studies.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.2
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• pp.67-81
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• 1988

The purpose of the present study is to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir and to establish a solid foundation for the automatic optimum structural design combined with finite element analysis. The major design variables are the dimensions and steel areas of each member of the structures. The construction cost which is composed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of the working stress design method. The corresponding design guides including the standard specification for concrete structures have been also employed in deraving the constraint conditions. The present nonlinear optimization problem is solved by SUMT method. The reinforced concrete intake-tower is decomposed into three major substructures. The optimization is then conducted for both the whole structure and the substructures. The following conclusions can be drawn from the present study. 1. The basis of automatic optimum design of reinforced concrete cylindrical shell structures which is combined with finite element analysis was established. 2. The efficient optimization algorithms which can execute the automatic optimum desigh of reinforced concrete intake-tower based on the working stress design method were developed. 3. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optImization algorithms developed in this study seem to be efficient and stable. 4. The difference in construction cost between the optimum designs with the substructures and with the entire structure was found to be small and thus the optimum design with the substructures,rnay conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the tensile stress insteel for salb, the minimum lonitudinal steel ratio constraints for tower body and the shearing stress in concrete, tensile stress in steel and maximum eccentricityconstraints for footing, respectively. 6. The computer program develope in the present study can be effectively used even by an unexperienced designer for the optimum design of reinforced concrete intake-tower.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.162-175
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• 2008

Gyeongju, which was the central city of the ancient civilization at Silla Kingdom, has various kinds of stone cultural properties. It is significantly important to preserve historical sources of Korea. However, recent air quality data measured in Gyeongju did not show good air quality level. In order to investigate variation of the concentration of the air pollutants with meteorological condition, an air quality monitoring and an aerosol sampling were conducted during the intensive monitoring period in Gyeongju. Impacts of the meteorological factors on the air pollutants were also analyzed based on the air mass pathway categories using HYSPLIT model and the local wind patterns using MM5 model. The prevailing air mass pathways were classified into four categories as following; category I affected by easterly marine aerosols, category II affected by northwesterly continental aerosols, category III affected by southwesterly continental aerosols, and category IV affected by northerly continental aerosols. The concentrations of the air quality standards were relatively lower during the fall intensive monitoring period. At that time, the easterly marine air mass pattern was dominated. The seasonal average mass concentration of $PM_{10,Opt}$, which optically measured at the monitoring site, was the highest value of $77.6{\pm}28.3\;{\mu}g\;m^{-3}$ during the spring intensive monitoring period but the lowest value of $20.1{\pm}5.3\;{\mu}g\;m^{-3}$ during the fall intensive monitoring period. The concentrations of $SO_2$ and CO were relatively higher when the air mass came from the northwestern continent or the northern continent. The concentrations of ${SO_4}^{2-}$ and ${NO_3}^-$ increased under the northwesterly continental condition. It was estimated that the acidic aerosols were dominated in the atmosphere of Gyeongju when the air mass came from the continental regions.