• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2010.04a
• /
• pp.697-699
• /
• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2010.04a
• /
• pp.700-702
• /
• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2010.04a
• /
• pp.685-686
• /
• 2010

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.6
• /
• pp.631-637
• /
• 2005

A UV-MFRSR instrument was used to measure the global and diffuse irradiances in 7 narrowband channels in the UV range 299.4, 304.4, 310.9, 317.3. 324.5, 331.3 and 367.4 nm at Gwangju ($35^{circ}\;13'N\;126^{circ}\;50'E$), Korea. Spectral UV-AOD was retrieved using the Langley plot method for data collected from April 2002 to July 2004. Temporal variation of AOD at 367.4 nm ($AOD_{367nm}$) showed a maximum in June ($0.95\pm0.43$) and a minimum in February ($0.31\pm0.14$). Clear seasonal variation of $AOD_{367nm}$ was observed with average values of $0.68\pm0.29,\;0.82\pm0.41,\;0.48\pm0.22\;and\;0.42\pm0.21$ in spring, summer, fall and winter, respectively, Average Angstrom exponent for the entire monitoring period was $2.03\pm0.75$ in the UV-A ($324.5\∼367.4$ nm) range. Seasonal variation of the Angstrom exponent showed a maximum in spring and a minimum in summer. The lowest Angstrom exponent in summer might be due to hygroscopic growth of particles under conditions of high relative humidity. UV-AOD changes under different atmospheric conditions were also analyzed. Uncertainty in retrieving spectral UV-AOD was also estimated to range between $\pm0.218\;at\;304.4\;nm\;and\;\pm0.135\;at\;367.4\;nm$. Major causes of uncertainty were total column ozone retrieval and extraterrestrial irradiance retrieval at shorter and longer wavelengths, respectively.

• Journal of Korean Society on Water Environment
• /
• v.36 no.4
• /
• pp.300-313
• /
• 2020

The Bayesian approach can be used to estimate hydrologic model parameters from the prior expert knowledge about the parameter values and the observed data. The purpose of this study was to compare the performance of the two Bayesian methods, the Metropolis-Hastings (MH) algorithm and the Generalized Likelihood Uncertainty Estimation (GLUE) method. These two methods were applied to the TANK model, a hydrological model comprising 13 parameters, to examine the uncertainty of the parameters of the model. The TANK model comprises a combination of multiple reservoir-type virtual vessels with orifice-type outlets and implements a common major hydrological process using the runoff calculations that convert the rainfall to the flow. As a result of the application to the Nam River A watershed, the two Bayesian methods yielded similar flow simulation results even though the parameter estimates obtained by the two methods were of somewhat different values. Both methods ensure the model's prediction accuracy even when the observed flow data available for parameter estimation is limited. However, the prediction accuracy of the model using the MH algorithm yielded slightly better results than that of the GLUE method. The flow duration curve calculated using the limited observed flow data showed that the marginal reliability is secured from the perspective of practical application.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.12
• /
• pp.233-243
• /
• 2020

This study aims to assess the impacts of COVID-19 on International Financial Reporting Standards (IFRS), because of the problems associated with changing and amending the financial reports according to the policies established based on the circumstances of the epidemic. The study sample targeted several international financial reports that were amended based on epidemic conditions. The revised financial reporting period provides standardized reporting procedures for financial transactions worldwide despite the pandemic. Therefore, IFRS has been used to reduce challenges in financial reporting by monitoring the duration of social distancing while reporting matters to eliminate confirmed uncertainty and judgment. After analyzing the data obtained through global search engines, the results conducted provided evidence that COVID-19 affects financial reporting in companies around the world. Therefore, companies face difficulty reporting finances based on the challenging environment that the pandemic represents. Besides, IFRS fair value measurements consider the prices that were predicted according to current market values. The contexts of the changing the standards by IFRS to curb the effects of the COVID19 financial reporting was attained through evaluation of the online files that were randomly selected and filtered to obtain valid data.

• Journal of Power Electronics
• /
• v.17 no.2
• /
• pp.551-560
• /
• 2017

The present study proposes an angle droop controller for converter interfaced (dispatchable) distributed generation (DG) resources in the islanded mode of operation. Due to the necessity of proper real and reactive power sharing between different types of resources in microgrids and the ability of systems to respond properly to abnormal conditions (sudden load changes, load uncertainty, load current disturbances, transient conditions, etc.), it is necessary to produce appropriate references for all of the mentioned above conditions. The proposed control strategy utilizes a current controller in addition to an angle droop controller in the discrete time domain to generate appropriate responses under transient conditions. Furthermore, to reduce the harmonics caused by switching at converters' output, a LCL filter is used. In addition, a comparison is done on the effects that LCL filters and L filters have on the performance of DG units. The performance of the proposed control strategy is demonstrated for multi islanded grids with various types of loads and conditions through simulation studies in the DigSilent Power Factory software environment.

• KIEAE Journal
• /
• v.15 no.6
• /
• pp.5-10
• /
• 2015

Purpose: To evaluate the economic performance of grid-connected photovoltaic system in residential house, household electricity bill policy of Korea Electric Power Corporation (KEPCO) must be applied precisely, and market tendency and uncertainty of system also need to be considered. In this study, to evaluate the economic feasibility of PV system, we measured PV power generation and electricity consumption of six of Green home in Daejeon through web based remote monitoring system. Method: We applied Monte-Carlo simulation based on life cycle cost analysis, to reflect an uncertainty of main factor in economic feasibility evaluation of photovoltaic system. Result: First, with deterministic analysis, the difference of NPV of cumulative financial savings among households varied from -3,310 ~ 24,170 thousand won, portraying notably big range. Also the possibility of getting the same result was 50% when applying uncertainty. Second, the higher electricity consumption is, the more economic feasibility of photovoltaic system increases because KEPCO uses progressive taxation in household electricity bill policy. Third, The contribution to variance of electricity price increases in NPV varied from 98.5% to 99.9%. While the inflation rate and annual degradation contributed very little to none.

• Knowledge Management Research
• /
• v.17 no.3
• /
• pp.117-136
• /
• 2016

External knowledge search is critical to expand the firm's knowledge base, increasing the innovation performance. However, prior literature has paid less scholarly attention on the boundary condition of the search activity. In particular, the few literatures on the contingency factors are either conceptual or focus on the firm characteristics such as resources and capability. In this regard, this study argues the negative moderating effect of knowledge protection and environmental uncertainty of a firm on the positive relationship between external knowledge search and innovation performance, because these contingency factors hamper the reciprocity and the mutual trust between the firm and its external partner that provides knowledge needed in the innovation process. The empirical analysis is based on the sample drawn from Korean Innovation Survey, provided by STEPI in Korea. The sample consists of 1,637 respondent firms that experienced product innovation during the survey period. We could find statistically supporting results for the negative moderating effect on the positive relationship between external knowledge search and innovation performance. This study extends the academic debate on the boundary conditions of external knowledge search and provides managerial implications for successful product innovation.

• Atmosphere
• /
• v.22 no.4
• /
• pp.437-447
• /
• 2012

There is still large uncertainty in estimating aerosol indirect effect despite ever-escalating efforts and virtually exponential increase in published studies concerning aerosol-cloud-precipitation interactions (CAPI). Probably most uncertainty comes from a wide range of observational scales and different platforms inappropriately used, and inherent complex chains of CAPI. Therefore, well-designed field campaigns and data analysis are required to address how to attribute aerosol signals along with clouds and precipitation to the microphysical effects of aerosols. Basically, aerosol influences cloud properties at the microphysical scales, "process scale", but observations are generally made of bulk properties over a various range of temporal and spatial resolutions, "analysis scale" (McComiskey & Feingold, 2012). In the most studies, measures made within the wide range of scales are erroneously treated as equivalent, probably resulting in a large uncertainty in associated with CAPI. Therefore, issues associated with the disparities of the observational resolution particular to CAPI are briefly discussed. In addition, the dependence of CAPI on the cloud environment such as stability and adiabaticity, and observation characteristics with varying situations of CAPI are also addressed together with observation framework optimally designed for the Korean situation. Properly designed and observation-based CAPI studies will likely continue to accumulate new evidences of CAPI, to further help understand its fundamental mechanism, and finally to develop improved parameterization for cloud-resolving models and large scale models.