• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.329-335
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• 2010

We investigate the sources of the variation of the high-latitude thermospheric neutral mass density depending on the interplanetary magnetic field (IMF) conditions. For this purpose, we have carried out the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM) simulations for various IMF conditions under summer condition in the southern hemisphere. The NCAR-TIEGCM is combined with a new empirical model that provides a forcing to the thermosphere in high latitudes. The difference of the high-latitude thermospheric neutral mass density (subtraction of the values for zero IMF condition from the values for non-zero IMF conditions) shows a dependence on the IMF condition: For negative $B_y$ condition, there are significantly enhanced difference densities in the dusk sector and around midnight. Under the positive-$B_y$ condition, there is a decrease in the early morning hours including the dawn side poleward of $-70^{\circ}$. For negative $B_z$, the difference of the thermospheric densities shows a strong enhancement in the cusp region and around midnight, but decreases in the dawn sector. In the dusk sector, those values are relatively larger than those in the dawn sector. The density difference under positive-$B_z$ condition shows decreases generally. The density difference is more significant under negative-$B_z$ condition than under positive-$B_z$ condition. The dependence of the density difference on the IMF conditions in high latitudes, especially, in the dawn and dusk sectors can be explained by the effect of thermospheric winds that are associated with the ionospheric convection and vary following the direction of the IMF. In auroral and cusp regions, heating of thermosphere by ionospheric currents and/or auroral particle precipitation can be also the source of the dependence of the density difference on the IMF conditions.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.195-201
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• 2011

The seaweed (Ascophyllum nodosum) extracts and chitosan formulations were sprayed on species of creeping bentrgass (Agrostis palustris Huds) cultivar "Penn A1" and species of Kentucky bluegrass (Poa pratensis L.) mixed cultivars (Midnight 33%, Moonlight 33%, Prosperity 33%) during fall season in sod farm. Turf color, chlorophyll contents and NDVI (Normalized Difference Vegetation Index) to affect turf qualities were investigated. There were detected significantly difference on chlorophyll contents and DNVI with seaweed extracts and chitosan formulations treatments. The contents of chlorophyll and NDVI on species of Kentucky bluegrass mixed cultivars and species of creeping bentgrass cultivar "Penn A1" were significantly increased by foliar spray with chitosan formulations and seaweed extracts. There was not a significantly difference on leaf color in two species within cultivars. These results suggested that chitosan formulations and seaweed extracts may help for turfgrass managements in the golf course during fall season.

• Journal of The Korean Astronomical Society
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• v.49 no.4
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• pp.163-173
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• 2016

In this paper, we study the lunar eclipse records in the Goryeosa (History of the Goryeo Dynasty), an official history book of the Goryeo dynasty (A.D. 918 - 1392). In the history book, a total of 228 lunar eclipse accounts are recorded, covering the period from 1009 to 1392. However, we find that two accounts are duplications and four accounts correspond to no known lunar eclipses around the dates. For the remaining lunar eclipses, we calculate the magnitude and the time of the eclipse at different phases using the DE406 ephemeris. Of the 222 lunar eclipse accounts, we find that the minimum penumbral magnitude was 0.5583. For eclipses which occurred after midnight, we find that some accounts were recorded on the day before the eclipse, like the astronomical records of the Joseonwangjosillok (Annals of the Joseon Dynasty), while others were on the day of the lunar eclipse. We also find that four accounts show a difference in the Julian dates between this study and that of Ahn et al., even though it is assumed that the Goryeo court did not change the dates in the accounts for lunar eclipses that occurred after midnight. With regard to the contents of the lunar eclipse accounts, we confirm that the accounts recorded as total eclipses are accurate, except for two accounts. However, both eclipses were very close to the total eclipse. We also confirm that all predicted lunar eclipses did occur, although one eclipse happened two days after the predicted date. In conclusion, we believe that this study is very helpful for investigating the lunar eclipse accounts of other periods in Korea, and furthermore, useful for verifying the calendar dates of the Goryeo dynasty.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.283-288
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• 2006

In the future television broadcasting a flood of information from various sources will not always be welcomed by everyone. The need of accessing specific information as required is becoming a necessity. We are interested to make the life of television consumer easier by providing an intelligent television set which can adaptively proposed certain shows to the viewer based on the user historical consumed shows. The TV watching history data consists of TV program titles with their respective genres, channels, watched times and durations, etc. The method proposed is by utilizing Hidden Markov Model (HMM) to model the user preference of kind of genres the viewer will watch based on recorded genres of several weeks time. We take watching schedule from 6 PM to midnight as boundary. The range thus divided into 3 independent time band of 2 hours each resulting in 3 time bands from 6 PM to 8 PM, 8 PM to 10 PM, and lastly 10 PM to midnight. Each time band will be represented by an HMM. From each HMM we can generate a sequence of predicted genre that the user will probably watch during corresponding time-band. Our approach assumes that the user shows a consistent behavior of watching pattern in week to week basis and during the moment of watching TV. To asses the method performance experiment is conducted using real data collected from December 2002 to May 2003. Some user's data are selected and based on that predictions are made. The resulting predictions are then compared with the actual user's history. The experiment shows satisfactory result for user with middle to high consistent behavior level.

• Journal of Korean Clinical Nursing Research
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• v.27 no.2
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• pp.165-178
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• 2021

Purpose: To analyze nurses' shift work according to the government guidelines for night work and their perceptions of their work schedules. Methods: The study sample included 487 nurses who provided information on their schedules, including the normal working hours of each shift, and overtime per shift during September 2020. Nurses' perceptions were measured in terms of satisfaction, appropriateness for work-life balance, and fairness to their work schedule. Results: One-third of the respondents worked more than 40 hours per week. The average overtime hour was 1.14 hours per shift. Unsocial hours (8 pm to 6 am on weekdays, midnight to midnight on weekends and public holidays) accounted for 56.4% of all working hours. During their last night shift, on average, nurses worked 9.62 hours and had a break of 39 minutes, although 20.5% reported no break. Sixty-eight percent of nurses had at least one between-shift break shorter than 48 hours after a consecutive night shifts. Fifty-seven percent were satisfied with their schedule. One-third perceived their schedule as appropriate for work-life balance, and two-thirds perceived that days off on weekends and nights were fairly distributed within the unit. Working and overtime hours had an inverse relationship with all three aspects of nurses' perceptions. A higher proportion of unsocial hours and having no breaks during the night shift were associated with lower perceptions of fairness. Conclusion: Reducing working hours, ensuring breaks during night shifts, and increasing rewards for unsocial hours are required to improve nurses' perceptions and reduce turnover due to shift work.

• Journal of Astronomy and Space Sciences
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• v.40 no.3
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• pp.101-111
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• 2023

We conducted a statistical study of polar mesospheric summer echoes (PMSEs) in relation to magnetic local time (MLT), considering the geomagnetic conditions using the K-index (or K). Additionally, we performed a case study to examine the velocity profile, specifically for high velocities (≥ ~100 m/s) varying with high temporal resolution at high K-index values. This study utilized the PMSE data obtained from the mesosphere-stratosphere-troposphere radar located in Esrange, Sweden (63.7°N, 21°E). The change in K-index in terms of MLT was high (K ≥ 4) from 23 to 04 MLT, estimated for the time PMSE was present. During the near-midnight period (0-4 MLT), both PMSE occurrence and signal-to-noise ratio (SNR) displayed an asymmetric structure with upper curves for K ≥ 3 and lower curves for K < 3. Furthermore, the occurrence of high velocities peaked at 3-4 MLT for K ≥ 3. From case studies focusing on the 0-3 MLT period, we observed persistent eastward-biased high velocities (≥ 200 m/s) prevailing for ~18 min. These high velocities were accompanied with the systematic motion of profiles at 85-88 km, including large shear formation. Importantly, the rapid variations observed in velocity could not be attributed to neutral wind effects. The present findings suggest a strong substorm influence on PMSE, especially in the midnight and early dawn sectors. The large zonal drift observed in PMSE were potentially energized by local electromagnetic fields or the global convection field induced by the electron precipitation during substorms.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.359-364
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• 2013

This study was conducted to develop a model to estimate crop leaf surface temperature. The results were as following; A definition for the daily time based on elapsed time from the midnight (00:00) as "E&E time" with the unit of Kmin. was suggested. The model to estimate the scaled temperature ($T^*e$) of crop leaf surface temperature by scale factor ($T^*$) according to the "E&E time : Kmin."(X) was developed as eq. (1) $T^*e=0.5{\cdot}sin(X+780)+0.5$ (2) $T^*=(Tx-Tn)/(Tm-Tn)$, Tx : Daily leaf temperature, Tm : Daily maximum leaf temperature, Tn : Daily minimum leaf temperature. Relative sensitivity of the measured temperature compared to the estimated temperature of red pepper, soybean and persimmon was 1.078, 1.033 and 0.973, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.278-287
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• 2009

Plug-in hybrid electric vehicle (PHEV) with capability of being recharged from the power-grid will reduce oil consumption. Also, the PHEV will affect the utility operations by adding additional electricity demand for charging. In this research, the power-grid impact by demand of PHEV charging is presented and the optimal charging control strategy for utility operators is proposed with simulated data. The penetration of PHEV is assumed to be 50% in the circumstances of Korean passenger car market and Korean power-grid market limitedly. To obtain smooth load shape and utilize the surplus electricity in power-grid at midnight and dawn, the peak of charging demand should be controlled to be located before 4:00 a.m., and the time slot which can supply the electricity power to PHEV should be allowed between 1:00 a.m.$\sim$7:00 a.m.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.956-958
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• 2001

기저부하조성 및 부하율 향상을 위한 심야 전력요금제도의 정착으로 최근 심야전력축열기기의 보급이 활성화되고 있다. 그러나 모든 심야전력축열기기들이 심야요금개시시간대인 22:00경에 동시에 가동됨에 따라 23:00에 심야전력 부하가 최대에 이르러 전력피크가 발생하여 한전의 수요관리에 큰 어려움을 주고 있다. 따라서 이 피크 부하를 심야전력 공급시간대의 저부하시간대로 분산시킬 수 있는 심야전력기기 통전시간제어가 필요하게 되었으며, 이에 개발된 알고리즘을 실증시험을 통하여 검증하게 되었다.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.369-371
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• 2002

기저부하조성 및 부하율 망상을 위한 심야 전력요금제도의 정착으로 최근 심야전력축열기기의 보급이 활성화되고 있다. 그러나 모든 심야전력축열기기들이 심야요금개시시간대인 22:00경에 동시에 가동됨에 따라 23:00경에 심야전력 부하가 최대에 이르러 전력피크가 발생하여 한전의 수요관리에 어려움을 주고 있다. 따라서 이 피크 부하를 심야전력 공급시간대의 저부하 시간대로 분산시킬 수 있는 심야전력기기 공급시간제어장치가 필요하게 되었으며, 이미 축열식전기보일러와 축열식 전기온수기에는 개발 보급되고 있는 실정이다. 이 논문에서는 다른 심야전력축열기기와는 달리 자연방열의 바닥축열난방방식인 축열식전기온돌의 공급시간자동제어장치 알고리즘을 실증실험을 통해서 검증하였다.