• Journal of the Korean Solar Energy Society
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• v.36 no.1
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• pp.63-73
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• 2016

How effectively a wind farm captures high market prices can greatly influence a wind farm's viability. This research identifies and creates an understanding of the effects that result in various capture prices (average revenue earned per unit of generation) that can be seen among different wind farms, in the current and future competitive SMP (System Marginal Price) market in South Korea. Through the use of a neural network to simulate changes in SMP caused by increased renewables, based on the Korea Institute of Energy Research's extensive wind resource database for South Korea, the variances in current and future capture prices are modelled and analyzed for both onshore and offshore wind power generation. Simulation results shows a spread in capture price of 5.5% for the year 2035 that depends on both a locations wind characteristics and the generations' correlation with other wind power generation. Wind characteristics include the generations' correlation with SMP price, diurnal profile shape, and capacity factor. The wind revenue cannibalization effect reduces the capture price obtained by wind power generation that is located close to a substantial amount of other wind power generation. In onshore locations wind characteristics can differ significantly/ Hence it is recommended that possible wind development sites have suitable diurnal profiles that effectively capture high SMP prices. Also, as increasing wind power capacity becomes installed in South Korea, it is recommended that wind power generation be located in regions far from the expected wind power generation 'hotspots' in the future. Hence, a suitable site along the east mountain ridges of South Korea is predicted to be extremely effective in attaining high SMP capture prices. Attention to these factors will increase the revenues obtained by wind power generation in a competitive electricity market.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.366-375
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• 2018

Evapotranspiration (ET) information is needed for many applications in agricultural and environmental resource management because crop yields, plant growth and physiological characteristics are primarily water limited. This study was conducted to evaluate the diurnal change of ET using electronic weighing lysimeter and to determine whether the ET of Cnidium officinale Makino could be manipulated through meteorological factors such as solar radiation, windy conditions and air temperature etc., Pot has a diameter of 35 cm and an height of 38 cm. A disturbed soil of sandy loam (coarse, mixed, mesic family of Dystric Fluventic Eutroudepts) within lysimeter has a mass of approximately 40.0 kg. In 2017, 10-minute recordings of data were used for measuring actual ET, and also evaluating a relationship between ET and meteorological factors during from 2 Aug. to 6 Aug. The maximum daily ET of Cnidium officinale was $44.04{\pm}3.949g$ per hour in lysimetric measurements. Diurnal changes of ET was highly correlated with solar radiation ($r^2=0.7778$) and followed by wind speed ($r^2=0.6400$). But on the other hand, air temperature was not consistent with ET ($r^2=0.2260$). This results imply that ET of Cnidium officinaele seems to be mainly governed by radiation energy in clear days, and approximately 40% of solar radiation is likely to be converted into ET. Therefore, weighing lysimeter can be used to accurately estimate actual ET and is expected to attract a great deal of attention to reliable application of water management in agriculture.

• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.29-33
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• 2007

This study was purposed to elucidate the best optimum sites by ecophysiological response measurements of Kalopanax pictus samplings of plantation. The diurnal changes of the stomatal transpiration, water use efficiency, water potential, and intercellullar $CO_2$ concentration of leaves were measured by the portable IR $CO_2$ analyzer. The results obtained are summarized as follows. 1) The daily stomatal transpiration rate was highest at 10:00 a.m. After 16:00, the stomatal transpiration rate rapidly decreased. 2) The daily water use efficiency was maximum at 8:00 a.m., and then rapidly decreased until midday with decreasing water potential. 3) The daily $C_i/C_a$ ratio rapidly decreased until 9:00 a.m., and then showed a stable value until 16:00, and then rapidly increased. The daily intercellullar $CO_2$ concentration ($C_i/C_a$ ratio) showed the same tendency as water potential changes. Consequently, stomatal transpiration and water use efficiency was increased with high water potential of leaves at am, and then remarkably decreased with low water potential at pm.

• The Korean Journal of Nuclear Medicine
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• v.17 no.1
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• pp.41-53
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• 1983

It is already well known that many factors are involved in maintaining normal blood glucose level. The amount and components of meal are also thought to be some of the factors which affect the blood glucose and insulin levels. It is reported that as for Koreans sugar takes up over 75% out of 2,098 kcal, the average daily calorie intake per adult. It implies that Koreans take a high-sugar diet compared with Westerners who take $40\sim50%$ of sugar out of their total average daily calorie. For the purpose of studying diurnal variations in serum glucose, insulin and C-peptide of normal Korean adults based on ordinary Korean diet, we selceted 13 normal Korean male adults and divided them into two groups, Group I (7 persons) and Group II (6 persons). We put Group I on 3,100kcal and 75% sugar diet, and Group II on 2,100 kcal and 69% sugar diet per day for over 4 days. Serum glucose, insulin and C-peptide were checked every 30 minutes or every hour throughout 24 hours. Results are as follows: 1. As for serum glucose level, in the prep ran dial fasting state in the morning, $mean{\pm}S.D.$ of Group I was $91.1{\pm}8.2mg%$, while that of Group II is $82.5{\pm}4.4mg%$. Both groups showed peaks of increased glucose level at postprandial 1 hour after each meal. The peak returned to the level shown during the fasting state at postprandial 1 hour after breakfast while the relatively high glucose levels were maintained respectively even for 2 or 3 hours.after lunch and dinner. 2. As for serum insulin level, Group showed $mean{\pm}S.D.$ of $14.7{\pm}3.0{\mu}U/ml$ while Group II shows that of $7.0{\pm}2.6{\mu}U/ml$ in the fasting state. Group I particularly showed the largest peak from preprandial a half or one and half an hour to postprandial one hour of lunch, and made relatively small peaks $(47.7{\pm}10.8{\mu}U/ml)$ at postorandial 1 hour after breakfast and dinner. No such large peak was marked in Group II, though it showed relatively similar patterns of peak after each meal. 3. As for C-peptide, in the fasting state, Group I and Group II showed $3.50{\pm}1.85$ and $1.66{\pm}0.53ng/ml$ of $mean{\pm}S.D.$, respectively. Group II showed peaks parallel to those for insulin level. None out of seven in Group I showed expected increase in C-peptide based insulin secretion at a half or one and half an hour before lunch. On the contrary, C-peptide increased in 5 subjects out of seven in Group I at 11:00 p.m. when insulin did not increase. 4. According to the integrated concentration method for a measurement of 24-hour total. insulin secretion rate, the $mean{\pm}S.D.$ of Group I was $76.4{\pm}15.2$ U and that of Group II was $58.6{\pm}21.1$ U. The above results confirm that Koreans, when given ordinary diet of 2,100 kcal and 69%, sugar, show insulin secretion pattern essentially similar to that of Westerners. On the contrary, when they are put on a high-calorie diet of 3,100 kcal a day, 75% of which is sugar, insulin secretion can be increased before lunch without increase in blood glucose. These results implies that insulin secretion can be affected by some other factors. The observation that an increase in C-peptide after 11 : 00 p.m. independent of insulin level supports an assertion that insulin secretion and C-peptide secretion can be thought as being physiologically dissociable, and these changes of diurnal patterns in the levels of serum insulin and C-peptide are thought to be resulted from the large meal and high-carbohydrate diet.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.153-156
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• 1986

A pot (1/200a) experiment was conducted to find out the changes of soil and water temperature on the several paddy soil weeds (Duck weed, Algae and Floatin fern) growing condition. The results obtained were shown as follows; 1. Diurnal maximum soil and water temperature were lowered by 2 to $3^{\circ}C$ under duck weed growing condition while minimum soil and water temperature were higher in $0.5^{\circ}C$ and/or similar tendency than that of bare paddy soil condition. 2. The changes of soil and water temperature were lowered by 0.1 to $0.3^{\circ}C$ at sunny day under Duck weed growing condition but was higher in 0.1 ta $0.4^{\circ}C$ at rainy, cloudy and after rainy day than that of bare paddy soil. 3. Soil and water temperature were higher about 0.3 to $1.0^{\circ}C$ under algae growing condition than that of bare paddy condition. 4. The effects of keeping warm efficiency were high in order of Duck weed > Duck weed with algae > algae > bare paddy soil condition.

• Tunnel and Underground Space
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• v.2 no.1
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• pp.116-122
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• 1992

A comprehensive, nonsteady state, computer simulation program for the environmental conditions in advancing tunnels (the HEADSIM simulation program) is constructed and successfully validated with heat balance amongst all heat sources, and with mass conservation amongst various airflows including the leakage air from ducts, under timedependent variations of inlet air conditions. which include sudden, diurnal and seasonal changes. Heat conduction in the wall strata and face strata is simulated with most complicated boundary conditions using the finite difference method, and the climatic conditions in roadway sections which contain air ducts, booster fan, spray cooler, compressed air pipes, cold water pipes, return water pipes, machinery and broken rock are simulated taking into account the variations of face operation and the heat storage mechanism in the strata. The limitations of simulation time steps and roadway section lengths are defined according to the stability criteria satisfying the principles of thermodynamics. Variations of heat transfer coefficients, which are newly set, and those of wetness factors are taken into account according to the variations of other parameters and the stepwise advance of the face. Newly-derived formulae are used for computing the air duct leakage and the pressure inside of the duct. A new concept of an 'imaginary duct' is introduced to simulate the climatic conditions in tunnels during holiday periods, which directly affect conditions on subsequent working days under the consideration of natural convection. A subsidiary program (the WALLSIM simulation program) is made to compute the dimensionless tunnel surface temperatures and to compare the results with those from analytical approaches, and to demonstrate the stability, convergence and accuracy of the strata heat conduction simulation, adopting the finite difference method. The WALLSIM also has wide applications, including those for the computation of age coefficients.

• The Korean Journal of Ecology
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• v.16 no.2
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• pp.159-168
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• 1993

The seasonal changes of symbiotic nitrogen-fixation activity and environmental factors of autumn olive plant (Elaeagnus umbellata Thunb.), which is an important constituent species of temperate vegetation and a non-leguminous root nodule plant interacting with Frankia sp., were quantitatively analyzed inthe natural vegetations during hegrowing period. The acetylene redution April and showed two peaks of 133 and $145{\mu}M\;C_2H_4\;{\cdot}\;gfw^{-1}\;{\cdot}\;hr^{-1}$ in early June and mid September. The nitrogenase activity decreased to 10~30% during hot dry summer frommid June to the end of August, and disappeared during the dormant period of winter. The optimum rhizoshere. diurnal change showed the maximum activity in the mid-day and the minimum in the mid-night. The average contents of total nitrogen in each organ changed in the ranges of 42.5~40.1, 40.2~36.3, 30.3~28.6 and 18.4~16.2mgN $gdw^{-1}$ for nodule, leaf, root, and stem, respectively. The soil conditions of rhizosphere were weak acidic, ad seasonal variations of $NO_3^--N,\;NH_4^+-N,\;PO_4^{3-}-P$ and water contents were in the ranges of 48.3~79.5ppm,5.1~13.9ppm, 4.4~$9.9{\mu}M$ and 14.5~39.4%, respectively.

• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.3
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• pp.141-146
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• 2015

Background: An understanding of the features of postoperative pain is essential for optimal analgesic dosing strategies. Using a visual analogue scale (VAS) score and patient controlled analgesia (PCA) infusion pattern analysis, an anesthesiologist can estimate when and how severely patients suffer from pain. Several reports have been published about circadian changes in the pain threshold. Postoperative pain was analyzed retrospectively in 250 patients who underwent orthognathic surgery. Methods: A total of 250 patients were allocated into two groups according to the time of recovery from anesthesia. Patients in the early group (group E) recovered from anesthesia before 06:00 p.m. Patients in the late group (group L) recovered from anesthesia after 06:00 p.m. All patients received intravenous patient controlled analgesia (IV PCA) at the end of the operation. The VAS score of pain intensity was measured. Self-administration of bolus analgesic from the IV PCA device was also analyzed according to actual time and elapsed time. Results: VAS scores showed no difference between the two groups except 36 hours after recovery from anesthesia. On POD1, there were two peaks for self-administration of bolus analgesics in group L and one peak in the morning for group E. Two peaks each in the morning and in the afternoon were shown in both groups on POD2. Conclusions: Diurnal variance in pain should be considered for effective dosing strategies.

• Ocean and Polar Research
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• v.25 no.1
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• pp.89-106
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• 2003

Analyses of tidal observations and a numerical model of the $M_2$ and $M_4$ tides in the Uldolmok waterway located at the southwestern tip of the Korean Peninsula are described. This waterway is well known fer its strong tidal flows of up to more than 10 knots at the narrowest part of the channel. Harmonic analysis of the observed water level at five tidal stations reveals dramatic changes in the amplitude and phase of the shallow water constituents at the station near the narrowest part, while survey results show a decreasing trend in local mean sea levels toward the narrow section. It was also observed that the amplitudes of semi-diurnal constituents, $M_2$ and $S_2$ are diminishing toward the narrowest part of the waterway. Two-dimensional numerical modeling shows that the $M_2$ energy flux is dominated by the component coming from the eastern boundary. The $M_2$ energy is inward from both open boundaries and is transported toward the narrow region of the channel, where it is frictionally dissipated or transferred to other constituents due to a strong non-linear advection effect. It is also shown that the $M_4$ generation is strong around the narrow region, and the abrupt decrease in the M4 amplitude in the region is due to a cancellation of the locally generated M4 with the component propagated from open boundaries. The superposition of both propagated and generated M4 contributions also explains the discontinuity of the M4 phase lag in the region. The tide-induced residual sea level change and the regeneration effect of the $M_2$ tide through interaction with $M_4$ are also examined.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.3
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• pp.211-223
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• 2000

The atmospheric dispersion of a pollutant emitted from a hypothetical source located in the middle of the Yochon Industrial Estate was simulated by using the Regional Atmospheric Modeling System (RAMS). Four horizontally nested grids were employed: the coarsest one covered the southern part of the Korean Peninsula including Mt. Chiri and the finest one covered the Yochon Industrial Estate and the surrounding area. Wind fields were initially assumed horizontally homogeneous with a wind speed of 4m/s, the average for the Yosu area, and were developed without both external forces and diurnal changes in order to investigate the terrain-induced phenomena. Wind directions that could emphasize the terrain effects on the pollutant transport and that could carry pollutants to a highly-popluated area were selected for the dispersion study. A pollutant was released for 24hours from a grid-base volume source after a 24-h blank run for developing the wind field. The dispersion study showed that the pollutant from the present source location did not directly affect the Yosu City, but showed high concentrations at locations behind the hills 5 to 6 km away from the source according to wind directions. When the wind speed was low, close to calm condition, the pollutant was detected at upstream locations 6 to 7 km from the source. In comparison with the results from the RAMS simulation, the Industrial Source Complex Short-Term Model(ISCST3) predicted a narrow dispersion that was sensitive to the wind direction. When the wind velocity was affected by the local environment, the ISCST3 calculation using that data also gave a lop-sided result, which was different from the distribution of the pollutant reproduced by RAMS.