• Korean Journal of Environmental Biology
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• v.35 no.2
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• pp.198-206
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• 2017

From June 2007 to May 2008, seasonal variations of bacterial abundance and heterotrophic nanoflagellate (HNF), together with environmental factors, were investigated at weekly and monthly intervals in Kyeonggi Bay. During the study period, the water temperature and salinity varied from $1.9^{\circ}C{\sim}29.0^{\circ}C$ and 31~35.1 psu, respectively. The concentration of ammonia, nitrate+nitrite, phosphate, and silicate ranged from 0.01 to $3.22{\mu}M$, 2.03 to $15.34{\mu}M$, 0.06 to $1.82{\mu}M$, and 0.03 to $18.3{\mu}M$, respectively. The annual average concentration of Chl. a varied from $0.86{\mu}g\;L^{-1}$ to $37.70{\mu}g\;L^{-1}$; the concentration was twice as much at the surface than at the deeper layers. The abundance of bacteria and HNF ranged from $0.29{\times}10^6$ to $7.62{\times}10^6cells\;mL^{-1}$ and $1.00{\times}10^2$ to $1.26{\times}10^3cells\;mL^{-1}$, respectively. In particular, there were significant correlations between bacteria and HNF abundance (p<0.05), and then the high abundance of HNF was frequently observed with an increase of bacterial abundance in summer (p<0.001). Our results therefore indicate that bacterial abundance in the bay was mainly controlled by resources supplied as organic and inorganic substances from Lake Shihwa due to the daily water exchange after dike construction. Also, the bacterial abundance was significantly controlled by HNF grazing pressure (top-down) in the warm seasons, i.e. excluding winter, in the Kyeonggi Bay.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.6
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• pp.327-340
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• 2017

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.279-286
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• 2014

The purpose of this study is to provide basic data of comparing BMD(bone mineral density) value of preoperative breast cancer patient and postoperative breast cancer patient due to bone loss with radiation/chemical therapy. The participants consisted of 254 breast cancer patients with BMD after having surgery and treatment from March 2007 to September 2013. Except for 84 patients with menopause or hysterectomy and we have analysed 171 patients. The BMD value(lumbar spine and femur) of before and after treatment from PACS by dure-energy X-ray absorptiometry was analyzed. First, we found variation of entire BMD and BMD according to treatment type, and analyzed detailed correlation by using marital status, number of children, presence of feeding, age of menarche, breast cancer therapy types as variable. Data was analyzed by using SPSS for Windows Program(version 18.0). BMD was decreased 7.1% in lumbar spine, 3.1% in femur respectively(p<.01). Also there is relatively high decrement($0.067g/cm^2$) in group who had just chemotherapy in femur(p<.05). There is decrement depend on marital status, number of children, presence of feeding, age of menarche, breast cancer therapy types but there was no statistical significance. The results show that BMD was decreased after treatment in premenopausal breast cancer patient, patient who had relatively high decrement need to be included high-risk group. As a result, aggressive prevention policy would be necessary.

• Journal of Korean Society of Transportation
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• v.18 no.1
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• pp.75-85
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• 2000

In existing models in optimization, the crisp data improve has been used in the objective or constraints to derive the optimal solution, Besides, the subjective environments are eliminated because the complex and uncertain circumstances were regarded as Probable ambiguity, In other words those optimal solutions in the existing models could be the complete satisfactory solutions to the objective functions in the Process of application for industrial engineering methods to minimize risks of decision-making. As a result of those, decision-makers in location Problems couldn't face appropriately with the variation of demand as well as other variables and couldn't Provide the chance of wide selection because of the insufficient information. So under the circumstance. it has been to develop the model for the location and size decision problems of logistics facility in the use of the fuzzy theory in the intention of making the most reasonable decision in the Point of subjective view under ambiguous circumstances, in the foundation of the existing decision-making problems which must satisfy the constraints to optimize the objective function in strictly given conditions in this study. Introducing the Process used in this study after the establishment of a general mixed integer Programming(MIP) model based upon the result of existing studies to decide the location and size simultaneously, a fuzzy mixed integer Programming(FMIP) model has been developed in the use of fuzzy theory. And the general linear Programming software, LINDO 6.01 has been used to simulate, to evaluate the developed model with the examples and to judge of the appropriateness and adaptability of the model(FMIP) in the real world.

• Journal of Korean Academy of Nursing
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• v.26 no.4
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• pp.946-962
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• 1996

The purpose of this study was to contribute to the development of clinical instruction by students' ratings of teaching effectiveness in clinical nursing education. The subjects were comprised of graduating class 618 students from 24 nursing colleges in the nation. The instruments used in this study were "general characteristics & status of clinical nursing education" developed by the researcher and "Instrument to Measure Effectiveness of Clinical Instructors" by Reeve(1994). The 50 questions used in the questionaire were categorized into 13 components subject to factor analysis. The 13 components were interpersonal relationships, communication skills, role model, resource for students, favorable to students, encouraging to think for selves, teaching methods, evaluation, finding assignments for objectives, organization of subject matter, professional competence, knowledge of subject matter & working with agency personnel. The results of this study are as follows 1. Status of clinical nursing educaion : 1) Clinical nursing education were led by nursing professors(44.9%), a team of both nuring professor & head nurse(6.8%), instructors from specific hospital(15.1%), instuctos for a specific subject(14.6%), & head nurse(6.8%). For 3-year program students, 34.6% of the clinical nursing education were led by instructors from specific hospital & 51.4% of the education by nursing professors for Bachelor's program. 2) The contents for clinical education comprised of Conference being the most frequent of 34.5% ; a combination of Nursing skills, Orientation, Conference etc.22.0% : Nursing process 21.7% : Orientation 13.5% : Inspection(making rounds ) 6.4%, & Nursing skills of 2% being the least frequent. 3) Students' preference of clinical teachers from the highest to the lowest were instructors for a specific subject being the most desired (44.9%) followed by nursing professor, head nurse, a team of both nursing professor & head nurse, & instructors from specific hospital being the least desired. 4) Students felt that the qualification for clinical teachers should be at least a master's degree holder and 5 or more years of clinical experience. The reason they felt was because knowledge & experience are imperative for professional education. 2. Clinical teaching effectiveness : The total points for teaching effectiveness was 147.97(mean of 2.95±0.98) where the total score is considered to be an average rating. 3. Teaching effectiveness as status of clinical nursing education : 1) The score ratings for the clinical instructors from the highest to the lowest were as follows : instructors for a specific subject, instructors from specific hospitals, a team of both nursing professors & head nurses, nursing professors, head nurses, which resulted in significunt difference(F=4.53, P<0.001). 2) The rating scores based on the teaching program from the highest to the lowest were as follws ; nursing skills, nursing process, a combination of nursing skills, orientation, conference etc. , conferences, orientation, inspection, which resulted in significunt difference(F=10.97, P<0.001). 4. Based on 13 categorized components from the questionaires, questions related to communication skills scored the highest points of 3.20 where inquiries regarding resource for students scored the lowest points of 2.38. 5. Among the 13 categorial components from the questionaire, Interpersonal relationship, Communication skills, Resource for students, Encouraging to think for selves, Evaluation, Teaching method, Finding assignment for objectives, Organization of subject matter, Professional competence, & Working with agency personnel, instructors for a specific subject scored the highest points and head nurse scored the lowest, which resulted in significant difference. Favorable for students, instructors for a specific subject scored highest points and nursing professor scored the lowest, which resulted in significant deference (F=5.39, P<0.001). Role model & Professional competence, instructors for a specific subject scored the highest points and head nurse scored the lowest, with minimum variation(F=1.29, P>0.05 : F=1.64, P>0.05) 6. Based on 13 categorial components as a whole, the highest points scored among the 5 groups of clinical teachers was instructors for a specific subject and the lowest, by head nurse(F=1.94, P<0. 001). A team of both nursing professor & head nurse attained higher score in clinical education than their independent education.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.3
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• pp.130-143
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• 1997

To investigate geochemical characteristics and the sources of the dissolved ion species in the river water in the Han river drainage basin, samples were collected at 60 sites from the Han river drainage basin. The data for. pH, conductivity, TDS (total dissolved solid), temperature, and concentrations of dissloved ions were obtained as follows : (1) The geochemical characteristics of the surface water in the South and North Han river drainage basins are mainly controlled by bed rock geology in the drainage basin and in the main stream of the Han river considerably affected by anthropogenic pollution. The South Han river water samples have high concentrations of $Ca^{2＋}$ (ave. 15.42 ppm), $Mg^{2＋}$ (ave. 2.74 ppm), HC $O_3$$^{[-10]}$ (ave. 51.9 ppm), which evidently indicates that the bed rock geology in a limestone area mainly controls the surface water chemistry. The concentration of S $O_4$$^{2-}$ is remarkably high (SHR10-2 : 129.9 ppm) because of acid mine drainage from the metal and coal mines in the upper reaches of the South Han river. (2) The South Han river and the North Han river join the Han river. in the Yangsuri, Kyounggido and flow through Seoul metropolitan city. The mixing ratio is about 60:40 at the meeting point (sample number HRl0). (3) The result of factor analysis suggests that the pollution factor accounts for about 79% and the bed rock type factor accounts for about 7% of the data variation. This means that the geochemical characteristics of the Han river water mainly controlled by anthropogenic pollution in the South Han river and main stream of the Han river drainage basin. (4) The chemical data for four tributaries such as the Wangsukcheon, the Tancheon, the Zunuangcheon, and the Anyangcheon show that the concentration of pollution elements such as N $O_2$, C $l^{－}$, P $O_4$$^{3-}$, S $O_4$$^{2-}$ and Mn are high due to municipal waste disposal.

• Progress in Medical Physics
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• v.17 no.3
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• pp.179-186
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• 2006

Purpose: Photon beam data of linear accelerators in Korea are collected, analyzed, and a simple method for checking and verifying the dose calculations in a TPS are suggested. Materials and Methods: Photon beam data such as output calibration condition, output factor, wedge factor, percent depth dose, beam profile, and beam quality were collected from 26 institutions in Korea. In order to verify the accuracy of dose calculation, ten sample planning tests were peformed. These Include square, elongated, and blocked fields, wedge fields, off-axis dose calculation, SSD variation. The planned data were compared to that of manual calculations. Results: The average and standard deviation of photon beam quality for 6, 10, and 15 MV were $0.576{\pm}0.005,\;0.632{\pm}0.004,\;and\;0.647{\pm}0.006$, respectively. The output factors of 6 MV photon beam measured at depth of dose maximum for $5{\times}5cm,\;15{\times}15cm,\;20{\times}20cm\;were\;0.944{\pm}0.006,\;1.031{\pm}0.006,\;and\;1.055{\pm}0.007$. For 10 MV photon beam, the values were $0.935{\pm}0.006,\;1.031{\pm}0.007,\;1.054{\pm}0.0005$. The collected data were not enough to calculate average, the output factors for 15MV photon beam with field size of $5{\times}5cm,\;15{\times}15cm,\;20{\times}20cm\;were\;0.941{\pm}0.008,\;1.032{\pm}0.004,\;1.049{\pm}0.014$. There was seven institutions $e{\times}ceeding$ tolerance when monitor unit values calculated from treatment planning system and manually were compared. The measured average MU values for the machines calibrated at SAD setup were 3 MU and 5 MU higher than the machines calibrated at SSD for 6 MV and 10 MV, respectively except the wedge case. When the wedges were inserted, the MU values to deliver 100 cGy to 5 cm depends on manufactures. When the same wedge angle was used, Siemens machine requires more MUs then Varian machine. Conclusion: In this study, photon beam data are collected and analyzed to provide a baseline value for chocking beam data and the accuracy of dose calculation for a treatment planning system.

• Journal of Radiation Protection and Research
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• v.39 no.1
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• pp.7-13
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• 2014

Phosphate rock, phosphogypsum, and products in phosphate processing facility contain naturally occurring radioactive materials (NORM). Therefore, they may give rise to enhanced radiation dose to workers due to inhalation of airborne particulates. Internal dose due to particle inhalation varies depending on particle properties. The objective of the present study was to characterize particle properties at the largest phosphate processing facility in Korea. A cascade impactor was employed to sample airborne particulates at various processing areas in the plant. The collected samples were used for characterization of particle size distribution, particle concentration in the air, and shape analysis. Aerodynamic diameters of airborne particulates ranged 0.03-100 ${\mu}m$ with the highest concentration at the particle size range of 4.7-5.8 ${\mu}m$ (geometric mean = 5.22 ${\mu}m$) or 5.8-9.0 ${\mu}m$ (geometric mean = 7.22 ${\mu}m$). Particle concentrations in the air varied widely by sampling area up to more than two orders of magnitude. The large variation resulted from the variability of mechanical operations and building ventilations. The airborne particulates appeared as spheroids or rough spherical fragments across all sampling areas and sampled size intervals. Average mass densities of phosphate rocks, phosphogypsums, and fertilizers were 3.1-3.4, 2.1-2.6, and 1.7 $gcm^{-3}$, respectively. Radioactivity concentration of uranium series in phosphate rocks varied with country of origin, ranging 94-866 $Bqkg^{-1}$. Among the uranium series, uranium was mostly concentrated on products, including phosphoric acid or fertilizers whereas radium was concentrated on byproducts or phosphogypsum. No significant radioactivity of $^{226}Ra$ and $^{228}Ra$ were found in fertilizer. However, $^{40}K$ concentration in fertilizer was up to 5,000 Bq $g^{-1}$. The database established in this study can be used for the accurate risk assessment of workers due to inhalation of airborne particles containing NORM. In addition, the findings can be used as a basic data for development of safety standard and guide and for practical radiation safety management at the facility.

• Journal of Venture Innovation
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• v.1 no.1
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• pp.83-98
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• 2018

This paper makes a theoretical approach to the differences between transaction tax and capital gains tax when the financial instruments are traded and imposed taxes in K-OTC market, a newly emerging off-board market. Since it is difficult to reduce risk to the level which investors would like to pursue - depending on the taxation methods of portfolio-composed financial instruments - when it comes to forming a synthetic bond to hedge risk, this paper also seeks for effective taxation methods to make this applicable. First of all, to thoroughly review the taxation balance of synthetic bonds, this paper analyzed the effects of the transaction tax and capital gains tax imposed upon synthetic bonds according to the changes in final stock price and strike price in K-OTC market, and analyzed after-tax profit differences among them depending on whether income tax deduction took place or not. As a result of the research upon the tax gap in transaction tax and capital gains tax according to the changes of final stock prices, it was shown that imposing transaction tax is more likely to be effective for some level of risk hedging with replicating portfolio considering taxation policies and financial markets, since the effect of the transaction tax has a much lower tax gap than that of capital gains tax. In addition, in relation to whether income tax deduction was permitted or not, it was proved that the effect of the transaction tax and the capital gains tax vary depending on the variation in the strike price. Above all, it was shown that if the strike price is lower than the stock price, the transaction tax will be less affected by the existence of income tax deduction than the capital gains tax, while both will be equally affected by the existence of income tax deduction if the strike price is higher than the stock price. Further study would be to demonstrate the validation of this in the K-OTC market with actual financial instruments and, also, to seek for a more systematic hedging method by using a ratio analysis approach to the calculation of the option transaction tax

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.86-94
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• 2010

This study compares and contrasts the dynamics of plankton in 31 temperate lakes and reservoirs, and considers particularly the biomass ratio of zooplankton to phytoplankton and ecological model application. A total of 89 species of zooplankton were identified (70 rotifers, 14 cladocerans and 5 copepods) and a total of 554 species of phytoplankton were identified (176 Bacillariophyceae, 237 Chlorophyceae, 68 Cyanophyceae, and 73 other algal taxa). The total plankton abundance and species diversity were showed distinctive spatial and seasonal variation. Annual average phytoplankton density was $7,350{\pm}15,592$ cells $mL^{-1}$ (n=124), and the lowest was $855{\pm}448$ cells $mL^{-1}$ (n=4), while the highest was $72,048{\pm}13,4631$ cells $mL^{-1}$ (n=4). For zooplankton, small rotifer groups dominated the study sites, and approximately 3~10 species appeared in the study sites. Statistical analysis and an ecological model application revealed that the size of reservoirs affected the structure size of plankton community, i.e. relatively large number of species were found in smaller reservoirs. From this result, we can conclude that management strategy for the reservoir environment has to be focused more on small-size reservoirs, in terms of plankton community ecology.