• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2013.11a
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• pp.23-24
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• 2013

Micrometeorological fluxes measured over a tall forest in a complex terrain are difficult to interpret. $CO_2$ storage often makes significant contributions to net ecosystem exchange of $CO_2$ (NEE) in early morning and during nighttime due to calm and stable conditions. We measured the above-canopy $CO_2$ flux along with its concentration profiles at eight levels within and above the canopy to evaluate $CO_2$ storage term. Our question is whether or not the $CO_2$ storage term can be estimated accurately from a single level measurement of $CO_2$ concentration in a complex terrain. Our objectives are (1) to document vertical profiles of $CO_2$ concentration and (2) to compare the diurnal and seasonal variations of $CO_2$ storages estimated from single and multi-level $CO_2$ concentration data. Seasonally averaged Diurnal variations of $CO_2$ concentration ranged from 398 to 455 ppm near the forest floor at 0.1 m whereas they ranged from 364 to 395 ppm at 40 m in the atmosphere. The diurnal variation of vertical profiles of $CO_2$ concentration shows very interesting features with season. At all eight levels, diurnal variation of $CO_2$ concentration showed little change in winter. In spring, the diurnal variations of $CO_2$ concentration at 8 levels showed three distinct groups of layers with height: the first layer: 0.1m (near surface), second layer: 1.0 m and 4.0m (below canopy) and the third layer: 7.4m to 40.7 m (near canopy and above). In summer, these three groups of layers were further separated with larger variations whereas such distinction became smaller in fall. The diurnal variation of $CO_2$ concentration in the first three layers near surface always showed higher concentration with larger variability. Typically, $CO_2$ concentration showed peaks in early morning and in the evening. After the evening peak, $CO_2$ concentration gradually increased except for those near the surface (i.e., 0.1, 1.0 and 4.0 m) where the concentrations actually decreased. We suspect that this could be attributed to the drainage flow of $CO_2$ along the hill slope from the headwater to downstream, which is not taken into account for net ecosystem $CO_2$ exchange. In comparison to the results of other studies, the distinct and different vertical structures of $CO_2$ concentrations observed at our site may be due to complex terrain and weak turbulent mixing under calm conditions at the site. The annual mean of diurnal variation of $CO_2$ storage flux from single level ranged from -0.6 to $0.9{\mu}mol\;m^{-2}s^{-1}$ and from multi-level from -1.2 to $1.0{\mu}\;{\mu}mol\;m^{-2}s^{-1}$. When compared against the results from the multi-level concentrations, the storage flux estimated from a single-level concentration was generally adequate except for specific hours near sunrise and sunset. Further details and their implication will be discussed in the presentation.

• Ocean and Polar Research
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• v.24 no.4
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• pp.491-500
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• 2002

Magnetic anomalies in the Dokdo and it's surroundings were investigated with respect to structure and origin of the Dokdo and surrounding seamounts. After normal and diurnal correction of measured magnetic data, crossover correction was applied to reduce errors between sets of magnetic anomalies. The errors from crossover operation result in decrease of about 51%, from 62.2 nT to 30.1 nT in standard deviation. Reduction-to-the-pole, second vertical derivative and analytic signal processing were applied to explore magnetic anomaly signatures in detail. Magnetic anomalies are most complicated in the 1st-Dok seamount, show SWW-NEE linear pattern in the 2nd-Dok seamount and lower to the 3rd-Dok seamount. Different magnetic anomaly patterns in three seamounts imply that three volcanic seamounts were formed at different times and are composed of rocks that were produced in different conditions. It seems that the 3rd-Dok seamount was first to form and followed by the 1st-Dok seamount. The complicated magnetic and second vertical derivative anomaly patterns in the 1st-Dok seamount may be due to subsidiary cones around crater or the presence of intruded magma bodies below sea surface and the Dokdo is probably a marginal subsidiary part of crater.

• Journal of Korean Society of Forest Science
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• v.63 no.1
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• pp.21-27
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• 1984

This study was to investigate the diurnal changes of shoot water potentials and the characteristics of xylem conductivity of branch in several conifers. The results obtained are as follows: 1) The diurnal shoot water potentials fluctuated with the sunlight intensities, and increase in shoot water potential lagged behind two hours as compared with the time of sunlight decrease in tree crown. 2) The shoot water potential reached the daily maximum ai twelve to fourteen o'clock in the afternoon, and the maximum shoot water potentials were -22 bar in Larix leptolepis, -18 bar in Pinus koraiensis, -15 bar in Pinus densiflora, -14 bar in Abies holophylla, and -10 in Pinus rigida. 3) The average gradient of shoot water potential per one meter height (${\varphi}_L/m$) in tree crown was -1.7 bar/m in Pinus koraiensis while that of Larix leptolepis was -2.1 bar/m. 4) The average of relative xylem conductivities (K, $cm^2/hr{\cdot}atm$) in branches was 2878 in Larix leptolepis, 2763 in Pinus rigida, 2652 in Pinus densiflora, and 2113 in Pinus koraiensis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.2
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• pp.130-136
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• 1982

Experiments were conducted to establish a measuring method of the stomatal aperture in the leaves of the wheat plant, and to find the diurnal movements of the stomate in leaves of different position and tillers. The measurement methods used were the infiltration and the microrelief impression methods. The aperture of the stomate in the infiltration method was expressed in terms of the solutions pent ration into the leaf and this was refered to as the infiltration score. A score I represents injection with 10% iso-butyl alcohol＋90% ethylene glycol solution and a score 7 represents injection with 70% iso-butyl alcohol +30% ethlene glycol solution. A linear relationship was obtained between the infiltration score and average pore width in a large number. of the stomata observed in the leaves of the adaxial and abaxial epidermis. The aperature of the stomate of flag and the 1st leaf were exhibited diurnal change with the maximum aperture at 10 A.M. but that of 2nd leaf reached maximum aperture 2 hours later than upper two leaves. After reaching the maximum aperture the stomata gradually closed and then completely closed at 6 P.M. The aperture of the stomate in the adaxial epidermis and the base part of the leaf were larger than those in the abaxial and top part of the leaf, and aperture of the stomate in the leaves of the main stem was larger than those on the tillers.

• Korean Journal of Agricultural and Forest Meteorology
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• v.26 no.3
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• pp.199-207
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• 2024

Measuring and estimating methane (CH₄) emissions accurately is important in rice paddy field. For reliable estimation, diurnal and seasonal variations of methane must be tracked, and measured frequently. The closed chamber method proposed according to the IPCC guidelines is relatively cheap and easy to move, so it is widely used, but it is difficult to estimate accurate methane emissions due to spatiotemporal constraints such as sampling time and number of measuring times. In this paper, the diurnal variation pattern was analyzed by measuring methane emissions four times at two-hour intervals throughout the day during the rice growth stage. When the emissions for each time period were converted to a daily time-weighted average, the diurnal average methane flux appeared in the time periods of 8:00~12:00 and 16:00~20:00. Through our results, we hope to provide useful information about determining reasonable times of methane measurement to researchers who measure methane emissions in rice paddy fields using the closed chamber method in the future.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.73-78
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• 2010

Purpose: The purpose of this study was to examine diurnal variation of accommodation on people whose age are between 35 and 50 years old with frequent alternation of accommodation at period 1 (8:00-10:00), period 2(13:00-15:00) and period 3 (18:00-20:00). Methods: All \04 subjects were separated to nonpresbyopia and incipient presbyopia. Tests were done for amplitude of accommodation, accommodative facility and relative amplitude of accommodation. Results: Both nonpresbyopia and incipient presbyopia had the highest amplitude of accommodation in oculus dexter, oculus sinister and oculus uterque at period 2. In addition, the incipient presbyopia showed the statistical significance of daily change. The nonpresbyopia had the most accommodative facility at period 3 and incipient presbyopia had the most accommodative facility at period 2. Their daily variations were statistically significant. Both nonpresbyopia and incipient presbyopia had the most negative relative accommodation of daily change at period I. Both of them had the most positive relative accommodation at period 2. Conclusions: The incipient presbyopia had the highest amplitude of accommodation, accommodative facility. and positive relative accommodation (except the negative relative accommodation) at period 2.

• Ocean and Polar Research
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• v.24 no.3
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• pp.207-213
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• 2002

We have analyzed sea surface temperature and salinity data collected in the western Pacific Ocean by using an automated Thermosalinograph (TSG) installed on the RV Onnuri during May - June of 2001. The TSG data exhibit characteristics of water masses distributed in the near surface layer of the cruise area very well. Especially, they reveal the diurnal surface temperature cycle and the effect of rainfall on temperature and salinity in the equatorial region, showing the effectiveness of the use of TSG. Problems to be improved for the better TSG operation are the method of water sampling and calibration of TSG sensors. Installation of a pressure gauge in the TSG system and periodical sensor calibration are strongly recommended to ensure reliability of data.

• Journal of Plant Biology
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• v.17 no.3
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• pp.107-112
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• 1974

Leaf temperature is complicated with the microclimate and the dry matter production in a plant community. But a daily change of leaf temperature varying by the locality in plant body or plant community is not yet clear. To resolve such a question, following experiment was designed; Helianthus tuberosus L., Glycine max L., Zea mays L., Impomoea batatas Lam., and Cucurbita moschata var. toonas Makino were planted in the different sandy loam, $2m{\times}2m-quadrat$, which has a eastern, southern, western and northern edge. In each plot 17-25 plants were planted and the distances between individuals spaced uniformly. And leaf temperature were measured by MR3-C type thermistor from 14th May through 20th August. It is seems that the upper leaf is affected by solar radiation, the lower leaf by released heat from the earth and the middle leaf by the conditions of both zones. Measuring the temperature of a leaf that is on terminal, central, left and right margins and base part, temperature of control plant in a leaf was sloped during about two hours from noon. It is noticeable as a "noon sleeping" phenomenon.henomenon.

• Journal of Environmental Science International
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• v.23 no.1
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• pp.25-37
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• 2014

In the present study, we analyzed precipitation patterns and diurnal variation trends of hourly precipitation intensity due to climate change. To that end, we used the hourly precipitation data obtained from 26 weather stations around South Korea, especially Busan, from 1970 to 2009. The results showed that the hourly precipitation was concentrated on a specific time of day. In particular, the results showed the so-called "morning shift" phenomenon, which is an increase in the frequency and intensity of hourly precipitation during the morning. The morning shift phenomenon was even more pronounced when a higher level of hourly precipitation intensity occurred throughout the day. Furthermore, in many regions of Korea, including Busan, this morning shift phenomenon became more prevalent as climate change progressed.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.384-386
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• 2003

GPS observation has been performed at Khon Kaen in northeast Thailand to investigate the Precipitable Water Vapor (PWV) change since August 2001 by using a Trimble 4000SSi receiver. The data obtained in the period from March to June in 2002 were processed by using CAMIT software to obtain the Zenith Tropospheric Delay (ZTD) at every one hour referring to some IGS stations around Thailand. We estimated the Zenith Hydrostatic Delay (ZHD) at every three hours with barometer data at Khon Kaen of Thai Meteorological Department, The Zenith Wet Delay (ZWD) was obtained by subtracting ZHD from ZTD and PWV can be calculated from ZTD. The results obtained shows that PWV changes with a large amplitude in March and April before the monsoon onset, and also we can see steep PWV increases before rain and decreases after rain. In May and June after the onset, the PWV is almost constant to be 60 to 70 mm, but there is a semi-diurnal change which has high PWV values at about 8 and 20 o'clock in local time.