• Journal of Korea Trade
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• v.23 no.6
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• pp.66-92
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• 2019

Purpose - Foreign Exchange Rates (FER) have been one of the most significant factors for both Korean exporters and the economy of Korea. The purpose of this study is to evaluate whether exporters with a high level of Exchange Rate Elasticity of Sales (ERES) make the use of earnings management for Income Smoothing (IS). Design/methodology - Income smoothing was obtained using the methodology suggested by Leuz, Nanda and Wysocki (2003). Accruals-based Earnings Management (AEM) was estimated using Discretionary Accruals (DA) calculated by the operant Jones Model developed by Dechow, Sloan and Sweeney (1995). Real Earnings Management (REM) was obtained using the methodologies suggested by Roychowdhury (2006) and Cohen and Zarowin (2010). Data were 2,402 firm years of public listed companies on the KRX, which were not in the financial industry and had a settlement of accounts in December for the period from 2013 to 2017. Findings - Results of the evaluation are as follows. First, companies with higher levels of ERES have relatively lower levels of smoothing of reported income. This might be because a fluctuation in sales caused by an exchange rate fluctuation has a direct impact on the volatility of the reported income. Second, companies with high levels of both ERES and IS have a positive correlation with both AEM and REM. This might be because companies with high levels of IS engage in earnings management to smooth reported income. Specifically, it is possible to assume that for smoothing the reported income, not only AEM but also REM is practiced. Third, companies with high levels of ERES but low levels of IS have a negative correlation with both AEM and REM. This could be interpreted as companies exhibiting low levels of IS due to higher levels of ERES tend to control IS. In addition, such results were supported by firms relying highly on exporting, and are consequently sensitive to exchange rate fluctuation. Therefore, it may conclude that companies with high levels of ERES make the use of earnings management as a means of IS. Originality/value - This study can find its significance from the fact that it is the first study, empirically verifying that companies of Korea, where exportation is a large part, use both AEM and REM as a means for smoothing reported income upon facing exchange rate fluctuations. In addition, it is highly expected that the results of this study could be useful for participants of financial markets when making IS-related decisions.

• Nuclear Engineering and Technology
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• v.14 no.4
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• pp.186-195
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• 1982

The steam line break accident for Kori Unit 1 is analyzed by a code SYSRAN which calculates nuclear power and heat flux using the point kinetics equation and the lumped-parameter model and calculates system transient using the mass and energy balance equation with the assumption of uniform reactor coolant system pressure. The 1.4 f $t^2$ steam line break accident is analyzed at EOL (End of Life), hot shutdown condition in which case the accident would be most severe. The steam discharge rate is assumed to follow the Moody critical flow model. The results reveal the peak heat flux of 38% of nominal full power value at 60 second after the accident initiates, which is higher than the FSAR result of 26%. Trends for the transient are in good agreement with FSAR results. A sensitivity study shows that this accident is most sensitive to the moderator density coefficient and the lower plenum mixing factor. The DNBR calculation under the assumption of $F_{{\Delta}H}$=3.66, which is used in the FSAR with all the control and the shutdown assemblies inserted except one B bank assembly and of Fz=1.55 shows that minimum DNBR reaches 1.62 at 60 second, indicating that the fuel failure is not anticipated to occur. The point kinetics equation, the lumped-parameter model and the system transient model which uses the mass and energy balance equation are verified to be effective to follow the system transient phenomena of the nuclear power plants.lear power plants.

• Journal of Environmental Health Sciences
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• v.42 no.2
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• pp.85-91
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• 2016

Objectives: The objective of this study was to assess heat stress, compare heat stress indices, and evaluate the usefulness of wet bulb globe temperature (WBGT) among outdoor workers exposed to heat during the summer season. Methods: WBGT, dry temperature, and heat index were measured using WBGT measurers (QUESTemp 32 model and QUESTemp 34 model, QUEST, WI, USA) by industrial hygienists from August 27 to September 16, 2015. Heat stress indices were measured at the workplaces of a shipbuilder in Ulsan and a construction site in Daegu. The dry temperature observed by the Automated Synoptic Observing System (ASOS) of the Korea Meteorological Administration was also compared. Results: Dry temperature measured by WBGT is different from that by ASOS. The temperature obtained from ASOS was less than $33^{\circ}C$, above which point a heat wave is forecast by the Korea Meteorological Administration. A heat index above $32.8^{\circ}C$ as a moderate risk was not observed during measurement. WBGT was consistently higher than $22^{\circ}C$, above which the risk of heat-related illness is increased in unacclimated workers involved in work with a high metabolic rate. WBGT was sometimes higher than $28^{\circ}C$, above which the risk of heat-related illness is increased in acclimated workers involved in work with a moderate metabolic rate in September. Conclusion: According to the measurement of heat stress indices, WBGT was more sensitive than heat index and temperature. Thus, general measures to prevent heat-related diseases should be implemented in workplaces during the summer season according to WBGT.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.373-386
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• 2017

This study simulated water quality item and flow rate of subbasin for Saemangeum watershed using Soil and Water Assessment Tool (SWAT) model and Environmental Fluid Dynamics Code (EFDC) model which simulate hydraulic and water quality in three-dimensions. The simulated values corresponded to observed value well. The result of simulation for floodgate operations at the M3 and M5 points, it exceeds water quality standard and at the M3 and D3 points, change of range for concentration is too wide, and upstream of Saemangeum reservoir is sensitive to inflow flow rate. Compared to the annual average concentration for observed station according to the discharge conditions, improvement of water quality for upstream was apparently compared to the downstream. Range of influence for change of water quality presented that maximum discharge condition, the influence range is 22 km in the direction of the Saemangeum downstream from the Mankyung bridge, and 15 km in the downstream direction of saemangeum in the Dongjin bridge. This study result demonstrated that floodgate operating at upstream has significant influence on water quality management of Saemangeum reservoir and it needs to be considered in plans of water quality management for Floodgate operation on Saemangeum reservoir.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.90-102
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• 2017

In this study, various types of nutrient models were tested by using two tears's water quality data collected from the stormwater wetland in Korea. Based on results, most important factor influencing nitrogen removal was hydraulic loading rate, which indicates that surface area of wetland is more important than its volumetric capacity, and model proposed by WEF was found to give a least error between measured and calculated values. For the phosphorus, in case assuming a power relationship between rate constant and temperature, the best prediction result were obtained, but temperature was most sensitive parameter affecting phosphorus removal. In addition, denitrification was always a limiting step for the nitrogen removal in this particular wetland mostly due to the lack of carbon source and high dissolved oxygen concentration. In this paper, several alternatives to improve nitrogen removal, including proper arrangement and designation of wetland elements and use of floating plants or synthetic fiber mat to control oxygen level and to capture the algal particles were proposed and discussed.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.17-27
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• 1993

To investigate the relationship between radiosensitivity and postirradiation recovery in human cancer cells, a study was performed using human cancer cell lines-A549, CaSki, SNU-C5 and PCI-13. For the study of radiosensitivity, single doses of 2, 4, 6, 8, 10, 12, and 14 Gy were given and for postirradiation recovery, two fractions of 4 Gy were separated with a time interval of 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, or 6 hours. Surviving fraction was estimated using colony forming ability. Surviving fractions at 2 Gy (SF2) were 0.496 (0.570-0.412) for A549, 0.496 (0.660-0.332) for CaSki, 0.386 (0.576-0.216) for SNU-C5, and 0.185 (0.247-0.123) for PCI-13. By statistical analysis the SF2 of PCI-13 was lower significantly than those of others (p<0.05). This difference was also observed at 4, 6 and 8 Gy dose levels. At 6 and 8 Gy the surviving fractions of SNU-C5 were also lower significantly than A549 and CaSki (p<0.05). By the analysis with linear quadratic model, the values of ${\alpha}$ for A549, CaSki, SNU-C5 and PCI-13 were 0.3016, 0.3212, 0.4327 and 0.8423, respectively, and those of ${\beta}$ were 0.02429, 0.02009, 0.03349 and 0.00059, respectively. So, the value of ${\alpha}$ showed increasing tendency with decreasing SF2. By the multitarget single hit model the values of Do for A549, CaSki, SUN-C5 and PCI-13 were 1.97, 1.97, 1.46 and 0.81, respectively, and those of n were 1.53, 1.50, 1.56 and 2.28, respectively. So, the value of Do decreased with decreasing SF2. Post-irradiation recovery reached plateau at around 2 hours. Recovery ratio at plateau phase ranged from 1.2 to 4.2; the value were 1.2 for PCI-13, 3.2 for CaSki, 3.3 for SNU-C5, and 4.2 for A549. Recovery rate well correlated with SF2, and increased with increasing Do and decreasing ${\alpha}$. According to above results, the intrinsic radiosensitivity was quite different among the tested cell lines; PCI-13 was the most sensitive and A549 and CaSki was similar. This difference of radiosensitivity is thought to be partly due to the difference in amount of postirradiation recovery. By linear quadratic model the difference of ${\alpha}$ values was very high, and by multitarget single hit model the difference of Do value was significantly high among four cell lines.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.253-263
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• 2016

Chrysanthemum production would benefit from crop growth simulations, which would support decision-making in crop management. Chrysanthemum is a typical short day plant of which floral initiation and development is sensitive to photoperiod. We developed a model to predict phenological development and leaf appearance of chrysanthemum (cv. Baekseon) using daylength (including civil twilight period), air temperature, and management options like light interruption and ethylene treatment as predictor variables. Chrysanthemum development stage (DVS) was divided into juvenile (DVS=1.0), juvenile to budding (DVS=1.33), and budding to flowering (DVS=2.0) phases for which different strategies and variables were used to predict the development toward the end of each phenophase. The juvenile phase was assumed to be completed at a certain leaf number which was estimated as 15.5 and increased by ethylene application to the mother plant before cutting and the transplanted plant after cutting. After juvenile phase, development rate (DVR) before budding and flowering were calculated from temperature and day length response functions, and budding and flowering were completed when the integrated DVR reached 1.33 and 2.0, respectively. In addition the model assumed that leaf appearance terminates just before budding. This model predicted budding date, flowering date, and leaf appearance with acceptable accuracy and precision not only for the calibration data set but also for the validation data set which are independent of the calibration data set.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.791-799
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• 2008

To build the system which has high utilization and usefulness for users, it is necessary to know the information type and use-demand that the use want. The purpose of this study is to forecast the preference and demand of utilization for bus information when bus information is offered through cellular phon. The accomplishments of this research are as follow : Firstly, importance on the level of individual factor and the value of change's figure can be evaluated, using preference analysis on bus information by conjoint analysis. Secondly, by establishing the use-demand model bus information using binary logit model, influence factor on whether or not the use of the user. Finally, ordered probit model was built by use behavior model in payment per call or per month of potential user of bus information. Through call times and sensitive analysis by payment methods, elasticity point, optimal payment fee, and use probability was analyzed. This study make application as basic to efficient bus information policy and to improve use rate of bus information in future because this study make it possible to get preference analysis, use-demand analysis and estimation of optimal payment fee which is reflecting various requirement in use of bus information user.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1907-1914
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• 2013

Textile-type heat exchangers installed on the tunnel walls for facilitating ground source heat pump systems, so called "energy textile", was installed in an abandoned railroad tunnel around Seocheon, South Korea. To evaluate thermal performance of the energy textile, a series of long-term monitoring was performed by artificially applying daily intermittent cooling and heating loads on the energy textile. In the course of the experimental measurement, the inlet and outlet fluid temperatures of the energy textile, pumping rate, temperature distribution in the ground, and air temperature inside the tunnel were continuously measured. From the long-term monitoring, the heat exchange rate was recorded as in the range of 57.6~143.5 W per one unit of the energy textile during heating operation and 362.3~558.4 W per one unit during cooling operation. In addition, the heat exchange rate of energy textile was highly sensitive to a change in air temperature inside the tunnel. The field measurements were verified by a 3D computational fluid dynamics analysis (FLUENT) with the consideration of air temperature variation inside the tunnel. The verified numerical model was used to evaluate parametrically the effect of drainage layer in the energy textile.

• The Journal of the Acoustical Society of Korea
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• v.31 no.6
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• pp.373-383
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• 2012

The performance of underwater acoustic communication system is sensitive to the Doppler shift and ISI(Inter-Symbol Interference). Therefore, the simulation algorithm needs to consider time-spread due to multipath arrivals which cause the ISI, and time-varying Doppler shift along with moving source and receiver. For this purpose, VirTEX(Virtual Time series EXperiment) based on Ray model has been developed. In this paper, VirTEX is used to compare the characteristics of ocean waveguide from the experimental data and illustrate the performance. The CIR(Channel Impulse Response) that characterizes the multipath arrivals with representative time-spread due to multipath arrivals is compared between numerically simulated and experimental probe signal. Also, the communication performance analysis for BER(Bit Error Rate) is compared between numerically simulated and experimental data signal. As a result, VirTEX can be useful as a simulation tool for evaluating the performance of underwater acoustic communication system.