• Korean Journal of Food Science and Technology
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• v.5 no.4
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• pp.231-234
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• 1973

Dried lavers, Porphyra yezoensis Ueda, were stored at $20^{\circ}C$ for 10, 25 and 45 days under a dry and humid conditions respectively, and changes in the contents of organic acids were studied by GLC and supplementary use of GC-MS. 1) Out of eight acids determined, i. e., pyruvic, lactic, oxalic, malonic, fumaric, succinic, malic, and citric acid, relatively abundant ones were oxalic, succinic, malic, and citric acid. 2) Oxalic, malic, and succinic acid did not show any notable changes in their contents under a dry condition, however, under a humid condition the contents of the former tow acids decreased rapidly showing contrast to that of succinic acid, of which content increased markedly. The content of citric acid rapidly· decreased independent of the storage conditions. 3) Among some unidentified components, two of them were presumed to be aromatic acids from their mass spectra. The contents of the two acids decreased slowly under a dry condition, however, rapidly decreased under a humid condition and after 45 days storage almost all of them disappeared. 4) The contents of total volatile acids were increased under the both storage conditions, however, the rate of increment was larger under a humid than under a dry condition.

• Applied Biological Chemistry
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• v.39 no.2
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• pp.118-122
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• 1996

The main objectives of this study was to characterize physicochemical properties, oxidative stability and sensory property of perilla oil obtained by various roasting temperature and time. Roasting temperature of perilla seed was conducted from $150^{\circ}C\;to\;210^{\circ}C$ at the increment of $20^{\circ}C$, and roasting time was 10, 20 and 30 min. Yield of perilla oil was increased as the roasting temperature and time were increased. The content of linolenic acid, a major fatty acid in perilla oil, was 60%. There was no differences in fatty acid composition upon the roasting conditions. Unsaturated fatty acid was contained more than 88% of the total fatty acids. Contents of phosphorus in perilla oils were decreased as the roasting temperature and time were increased. Phosphorus contents were significantly decreased at $190^{\circ}C$ for 30 min and $210^{\circ}C\;for\;20{\sim}30$ min. Tocopherol contents were unchanged at the roasting conditions of present study and gamma-tocopherol was shown to be the major tocopherol. Sensory evaluation of perilla oil roasted in various conditions showed significant differences in taste, color, flavor and palatability. The perilla oil roasted at $190^{\circ}C$ for 20 min had the best palatability.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.4
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• pp.282-288
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• 2005

This study was carried out to estimate aboveground carbon contents associated with four years of thinning treatment of Quercus acuta stands in Wando Arboretum, Jeonnam. Stand thinning was conducted over four years using stand table projection for each thinning treatment. Ten sample trees were cut in the surveyed area. Estimation of aboveground biomass was made using the equation model $W=aD+bD^2$ where W is oven dry weight and D is DBH in cm. The total aboveground biomass for each intensity treatment area was : control (148.4 ton/ha), light (105.6 ton/ha), moderate (68.7 ton/ha) and heavy (39.1 ton/ha). Aboveground carbon storage for Quercus acuta stands was found by multiplying dry weigh t (ton/ha) by 0.5. Carbon storage and increment after four years was: control (74.2 tonC/ha), light (52.8 tonC/ha), moderate (34.3 tonC/ha) and heavy thinning intensity area (38.2tonC/ha).

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.295-302
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• 2005

The nitrogen (N) balance in Korea during 1985-1997 was calculated according to the surface balance method of the PARCOM guidelines and compared with Japanese N balance. The some differences were founded in the coefficients used on calculating N balance in two nations. Of the important parameters, which can make a big difference in balance, N input by organic fertilizers was not included in Korea different with Japanese, due to absence of reliable statistics and then made lower the input. Nitrogen destruction rate from livestock manure was adjusted differently with 15% in Korea but 28% in Japan. There was some difference in the conversion factors of livestock number into manure N quantity in two nations, but the gap was ignoble scale except beef cattle. Our manure N production rate of beef cattle might be evaluated to be so lower than Japanese. Biological N fixation by pulses was very higher in Korea than in Japan but scarcely affect the increase of total N input, due to small cultivation area. In contrast, N fixation rate by free-living organisms in Korean and Japanese wet paddies showed the big difference with 7.6 and $37.0kg\;ha^{-1}\;yr^{-1}$, respectively, and therefore $29.4kg\;ha^{-1}\;yr^{-1}$ of nitrogen was estimated to be more inputted in Japan. Although there are many points to be more specified and improved, still, Korean N balance was very high with $250-257kg\;ha^{-1}$ in the mid of 1990s, which was the second highest level in OECD countries and furthermore increased continuously during the investigation. In contrast in Japan, which has similar fanning system with Korea, N balance was lower with $130-158kg\;ha^{-1}$ and has decreased continuously since 1993. This high N balance was mainly due to a high usage of chemical fertilizers in our intensive fanning system and the fast increment of livestock feeding. Therefore, the more active action to decrease chemical fertilizer utilization and reduce livestock feeding density is required in the government and farmer sides.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.339-344
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• 1990

The composition of muscle lipids and their fatty acid composition of two groups of tilapia, cultured in fresh and seawaters, were investigated. The total lipid(TL) of seawater culture group is a little richer than that of freshwater culture. The neutral lipid(NL) is the most abundant in muscle lipids of two groups, followed by the phospholipid(PL) and glycolipid (GL). The increment of TL content seemed to depend upon triglyceride(TG) fraction, because large portions of lipids are consisted of TG. Phosphatidyl choline(PC), phosphatidyl ethanolamine and sphingomyelin were identified in PL, and the content of PC was the highest. The principal fatty acids of muscle lipids were 14 : 0, 16 : 0 and 18 : 0 as for saturated fatty acids, and 16 : 1, 18 : 1, 18 : 2 and 22 : 6 as for unsaturated fatty acids. In particular, high contents of 16 : 0 and 18 : 1 were observed in TL, NL and GL. However, low contents of 18 : 1 and 18 : 2 were observed in PL, while they were high in polyunsaturated fatty acids with 20 : 4, 20 : 5 and 22 : 6. In the meantime, no significant difference was observed in the composition of muscle lipids and their fatty acids between two groups cultured in seawater and freshwater.

• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.364-373
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• 1999

This study aims to clarify the effect of forest management practices(thinning and pruning) on soil physical properties and water quality to get the fundamental information on the facility of purifying water quality after forestry practices. Rainfall, throughfall, stemflow, soil and stream water were sampled at the study sites which consist of Abies holophylla and Pinus koraiensis, in Kwangnung Experimental Forest for 6 months from March 1 to August 7, 1998. Average tree height of the management site increased by 1.8m and 0.6m more than that of the non-management site in Abies holophylla and Pinus koraiensis, respectively. Increment of average D.B.H. at the management site showed 4.7cm and 1.4cm more in Abies holophylla and Pinus koraiensis compared with that at non-management sites. Coarse(less than pF2.7) and total porosities of A layer soil at the management site increased more than those at the non-management sites in both stands. Otherwise, soil bulk density resulted in being reversely. Water qualities of throughfall, stemflow and soil water were buffered more by the management practice in both.

• Journal of the Korean Geophysical Society
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• v.3 no.2
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• pp.127-138
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• 2000

This study was conducted to examine the differences between dynamic and static elastic constants by use of some laboratory tests of cement mortar specimens which have different water/cement mixing ratios. Specific gravity measurement, ultrasonic velocity estimating and uniaxial compression test were adopted to acquire the dynamic and static elastic constants. Digital data acquisition and processing enhanced the accuracy of estimating the velocities of specimens drastically, Also, the method using the gradient of propagation delay time in according to increment of specimen length more enhanced the accuracy than the method using the only one specimen length over total propagation time. The correlation between density and the P and S wave velocity of specimens shows reliable positive relation and the correlation between density and the strength of uniaxial compression has the similar relationship. The dynamic Young's modulus $(E_D)$ is alway greater than the static Young's modulus $(E_S)$ and there is increasing tendency of the ratio $(E_D/E_S)$ according to the increase of density or strength of the specimens. On the other hand, there is no typical relationship between dynamic Poisson's ratio $({\nu}_D)$ and static Poisson's ratio $({\nu}_S)$ and just the ratio of ${\nu}_D/{\nu}_S$ ranges front 69 to 122 %.

• Journal of Environmental Health Sciences
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• v.30 no.2
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• pp.140-148
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• 2004

To evaluate the acute effects of fine particles on pulmonary function, a longitudinal study was conducted. This study was carried out for the schoolchildren (3rd and 6th grades) living in Beijing, China. Each child was provided with a mini-Wright peak flow meter and a preformatted health symptom diary for 40 days, and was trained on their proper use. Participants were instructed to perform the peak flow test three times in standing position, three times a day (9 am, 12 pm, and 8 pm), and to record all the readings along with the symptoms (cold, cough, and asthmatic symptoms) experienced on that day. Daily measurement of fine particles (PM$_{10}$ and PM$_{2.5}$) was obtained in the comer of the playground of the participating elementary school for the same period of this longitudinal study. The relationship between daily peak expiratory flow rate (PEFR) and fine particle levels was analyzed using a mixed linear regression models including gender, height, the presence of respiratory symptoms, and daily average temperature and relative humidity as extraneous variables. The total number of students participating in this longitudinal study was 87. The range of daily measured PEFR was 253-501$\ell$/min. In general, the PEFR measured in the morning was lower than the PEFR measured in the evening (or afternoon) on the same day. The daily mean concentrations of PM$_{10}$ and PM$_{2.5}$ over the study period were 180.2$\mu\textrm{g}$/㎥ and 103.2$\mu\textrm{g}$/㎥, respectively. The IQR (inter-quartile range) of PM$_{10}$ and PM$_{2.5}$ were 91.8$\mu\textrm{g}$/㎥ and 58.0$\mu\textrm{g}$/㎥. During the study period, the national ambient air quality standard of 150$\mu\textrm{g}$/㎥ (for PM$_{10}$) was exceeded in 23 days (57.5%). The analysis showed that an increase of 1$\mu\textrm{g}$/㎥ of PM$_{10}$ corresponded to 0.59$\mu\textrm{g}$/㎥ increment of PM$_{2.5}$. Daily mean PEFR was regressed with the 24-hour average PM$_{10}$ (or PM$_{2.5}$) levels, weather information such as air temperature and relative humidity, and individual characteristics including gender, height, and respiratory symptoms. The analysis showed that the increase of fine particle concentrations was negatively associated with the variability in PEFR. The IQR increments of PM$_{10}$ or PM$_{2.5}$ (at 1-day time lag) were also shown to be related with 1.54 $\ell$/min (95% Confidence intervals: 0.94-2.14) and 1.56$\ell$/min (95% CI: 0.95-2.16) decline in PEFR.R.ine in PEFR.ine in PEFR.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.563-569
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• 2016

This paper presents the resizing method of columns and beams that considers column-to-beam strength ratios to simultaneously control the initial stiffness and ductility of steel moment frames. The proposed method minimizes the top-floor displacement of a structure while satisfying the constraint conditions with respect to the total structural weight and column-to-beam strength ratios. The design variable considered in this method is the sectional area of structural members, and the sequential quadratic programming(SQP) technique is used to obtain optimal results from the problem formulation. The unit load method is applied to determine the displacement participation factor of each member for the top floor lateral displacement; based on this, the sectional area of each member undergoes a resizing process to minimize the top-floor lateral displacement. Resizing members by using the displacement participation factor of each member leads to increasing the initial stiffness of the structure. Additionally, the proposed method enables the ductility control of a structure by adjusting the column-to-beam strength ratio. The applicability of the proposed optimal drift design method is validated by applying it to the steel moment frame example. As a result, it is confirmed that the initial stiffness and ductility could be controlled by the proposed method without the repetitive structural analysis and the increment of structural weights.

• Asian Journal of Turfgrass Science
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• v.1 no.1
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• pp.56-68
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• 1987

During the regrowth the process after mowing, NRA in the leaf was the highest activity from the 5th day to the 7th day. Before mowing, the NRA in the root was not almost detected. But, the NRA in root appeared a rapid increasing activity from the 3rd day to the 4th day after mowing ( Figs.27 ~ 32). During the regrowth process after mowing, a general tendency of AA in the aboveground parts appeared an increasing tendency from the 1st day to the 4th day, a rapid increasing tendency from the 7th day to the 8th day reaching its peak, and a decreasing rate on the 8th and 9th day reaching its peak, and a decreasing rate on the 8th and 9th day. But the AA in the root appeared rapid increasing rate from the 2nd day to the 7th day, the heginning of reagrowth, this tendency showed a similar figure in the case of Total Soluble Carbohydrate ( TSC) in the internode. Both AA and NRA were appeared recovery stage frorn the 8th day after mowing(Figs.15~20). During the regrowth process after mowing, changes of the maximum plant lengths were 18.27cm in the 6cm mowing plot on the 24th day after mowing, 18.83cm in the 3cm mowing plot on the 18th day after mowing, and 18.16cm in the 6cm mowing plot on the 14th day after mowing ( Fig.2). During the regrowth process after mowing. changes in Dry Matter (DM) contents in leaf and stem were a slow decreasing tendency from the 1st day to the 4th day. From the 5th day to the 8th day it appeared a rapid increasing tendency. And afterward until the 15th day. All treatments were reached at a steady state ( Figs.3 ~ 8). During the regrowth process after mowing, changes in the TSC contents of stem and crown were a slow decreasing tendency from the 1st day to the 5-6th day. Prom the 7th to the 8th day three was a rapid increasing tendency. And afterward until the 15th day there was a decreasing rate at a steadyv state. In root there was a similar tendency to that of leaf and stem organs. A general tendency in internode, the TSC content appeared a similar figure to increment of AA (Figs. 9 - 14). During the regrowth process after mowing, changes in te Crude Proem (CP) content of ahoveground parts appeared a slow increasing tendency from the 1st day to the 5-6th day, where it is peak. And afterward to the 15th day there was a decreasing rate at a steady state. But, in toot there were a contrary tendency to that of aboveground