• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.221-229
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• 2004

In Recent experimental research results of connection method between steel pipe pile and concrete footing are provided based on various experimental observations. It gives a shedding light toward developing better connection method for steel pipe pile at the field application. In this study, the newly developed method is tested for compressive, pull put and combination load including moment with carefully designed monitoring system. The measured data show that new method have at least equivalent or better load resistant capacities compared with those of specified method in Korea Road Design Specification. It is also tried to define and investigate the load transfer mechanism for new method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.98-101
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• 2022

Liquid-based Triboelectric nanogenerator (L-TENG) is one of the alternatives to solid-based Triboelectric nanogenerator (S-TENG) because of the absence of surface damage which can decrease the durability of the generator. However, the L-TENG also has an obvious drawback of significantly lower output than that of S-TENG. This article produces water-sloshing-based electricity generating device (W-ED) with a new design of L-TENG that improves electrical output in portable form. The dual-electrode system, consisting of closed-loop circuit and inner electrode which enables water to contact directly in the bottle, can generate the open-circuit voltage and the short-circuit current of up to 348 V and 5.1 mA, respectively. By investigating the motion of water for each frequency, we propose that W-ED is suitable device for a variety of human motions. We expect that W-ED can be applied in small electrical devices or sensors in daily-use items.

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.266-272
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• 1999

Aboveground biomass and nutrient contents of a 31-year-old pitch pine(Pinus rigida) and a 31-year-old Japanese larch(Larix leptolepis) plantations were measured in the Chungbu Forest Experiment Station, Kyunggi Province. Aboveground biomass was 170.2ton/ha in the pitch pine and 87.2ton/ha in the Japanese larch plantations. Aboveground biomass difference between both plantations was due to the difference of stand density. Aboveground biomass in both plantations was allocated as follows : stemwood>branch>stembark>needle. The concentrations of all nutrients(N, P, K, Ca, Mg) were generally higher in the Japanese larch needle than in the pitch pine because of high nutrient uptake characteristics of larch compared with pine tree species. The nutrient concentration in different tree tissues in both tree species decreased in the order of needle>branch>stembark>stemwood. Nutrient contents of aboveground biomass were : N, 335.9 ; P, 40.4 ; K, 121.4 ; Ca, 188.6 ; Mg, 93.8kg/ha in the pitch pine plantation, while nutrient contents in the Japanese larch plantation were : N, 226 ; P, 11.5 ; K, 72.9 ; Ca, 75.7 ; Mg, 37.1kg/ha. The nitrogen use efficiency calculated as the biomass produced by one unit of nitrogen was higher in the pitch pine than in the Japanese larch plantations. This result suggests that pine with high nitrogen use efficiency could be adapted in lower site productivity area compared with larch tree species.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.473-478
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• 2009

The purpose of this study is to evaluate the behaviour of the plastic deformed zone at crack tip on the standard Charpy specimens which were taken from the multi-passed weld block of the pressure vessel steel. Notch was machined on the standard Charpy test specimens and pre-crack which was located around the fusion line was made under the repeat load. Four point bend and acoustic emission tests were carried out simultaneously. The size of plastic region at crack tip was calculated using stress intensity factor. Relationships between characteristics of acoustic emission and plastic zone size at crack tip were discussed through the cumulative AE energy. Regardless of the specimens, AE signals were absent within the elastic region almost and most of AE signals were produced at the plastic deformation region from yield point to the mid-point between yield and maximum load. More AE signals for the weldment were produced compared with the base-metal and PWHT specimen. Relations between plastic deformed zones at crack tip and cumulative AE energy for the weldment and PWHT specimen were different quietly from the base-metal. Besides, number of AE counts for the weldment was the larger than those of the base-metal and PWHT specimen.

• Journal of Korean Society of Forest Science
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• v.88 no.4
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• pp.462-468
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• 1999

A natural mixed forest of Pinus densiflora and Quercus variabilis in Mt. Mohu area was studied to investigate patterns of species competition and productivity. Ten $10m{\times}10m$ plots were set up and eight sample trees of each Pinus densiflora and Quercus variabilis were harvested for dimension analysis. Mean tree age of Pinus densiflora was 33 years and that of Quercus variabilis was 26 years. DBH and height of Quercus variabilis were larger than those of Pinus densiflora untill tree age 15. After tree age 15, height of Quercus variabilis was higher than height of Pines densiflora while DBH of Quercus variabilis was smaller than DBH of Pines densiflora. For a tree of a given DBH, there was little difference in leaf dry weight between Pines densiflora and Quercus variabilis. For a tree of a given DBH, dry weights of stem wood, stem bark and branches of Quercus variabilis weighed more than those of Pinus densiflora, and the differences between the dry weights of the two species became greater as DBH increased. Net assimilation ratio of Quercus variabilis was higher than that of Pinus densiflora, and biomass accumulation ratio of Quercus variabilis was lower than that of Pinus densiflora. It may be given as a conclusion that Quercus variabilis was superior to Pinus densiflora in species competition owing to faster height growth, higher net assimilation ratio, and lower biomass accumulation ratio. Aboveground stand biomass was 87.7t/ha and aboveground stand net production was 8.3t/ha/yr.

• The Korean Journal of Malacology
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• v.24 no.3
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• pp.253-260
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• 2008

A total of 15 different residues of polycyclic aromatic hydrocarbons (PAHs) in each 20 samples of Pacific oysters, dried laver and rockfish obtained from seafood markets were analyzed. The prevalence of samples in which more than one PAH residues were found was 75% in oyster, 35% in rock fish hepatopancreas, 0% in rockfish muscle and laver, respectively. To estimate factors contributing to this residue level difference among organisms, tissue concentrations were analyzed after exposing three organisms to phenanthrene, a representative PAH, with concentration of 0.01 or $0.1{\mu}g/mL$ for 2 weeks. Phenanthrene levels after exposure were higher in the oyster digestive gland, laver and rockfish hepatopancreas, but were lower in the oyster whole meat or rockfish muscle. This finding disproved that any close relationship between the residue difference of market samples and concentrating properties of PAHs. The second possible factor analyzed was total lipid contents in the three organisms. Although higher lipid level in hepatopancreas of rockfish may contribute accumulation of PAH residues in the rockfish, lipid factor did not affect to PAH levels in other organism samples. Activity of 7-ethyoxyresorufin-O-deethylase (EROD), a kind of cytochrome $P_{450}$ enzyme, was measured to evaluate the eliminated amount of PAHs through metabolism. The higher EROD activity in rockfish, compared to that in oyster, was likely to contribute to the lower PAH residues in the rockfish. More factors, such as different exposure history, organisms' ability to escape, ingestion through prey organisms, and post-harvest loss, should be studied in the future.

• Journal of Korean Society of Steel Construction
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• v.20 no.5
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• pp.625-632
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• 2008

In the companion paper (Model Development), an analytical model estimating the available rotation capacity of fully restrained beam-column connections in special steel moment-resisting frames was proposed. In this paper, two limit states were considered as the connection rotation capacity criteria: (i) strength degradation failure when the strength falls below the nominal plastic strength due to the local buckling of the beam's cross-section and (ii) low-cycle fatigue fracture caused by plastic strain accumulation at the buckled flange after only a few cycles of high-amplitude deformation. A series of analyses are conducted using the proposed model with two limit states under monotonic and cyclic loadings. Beam section geometric parameters, such as flange and web slenderness ratios, varied over the practical ranges of H-shapedbeams to observe their effect on the rotation capacity and low-cycle fatigue life of pre-qualified WUF-W connections.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.67-75
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• 2011

The purpose of this study is to evaluate the flow duration characteristics of Nakdong, Seomjin and Geum river due to environmental change. The water level gauging stations of Nakdong, Seomjin and Geum river were selected to analyze the change of flow duration. The construction period of multipurpose dam was considered to analyze flow duration characteristics. As the result of this study, it show that ninety-five day flow, normal flow, low flow and drought flow were increased by multipurpose dam construction at all stations except a Jukpo gauging station. Especially, improved effect of flow duration in downstream part was bigger than that in upstream and midstream part. The coefficients of river regime of Nakdong, Seomjin and Geum river were decreased and also coefficients of flow duration were decreased after the multipurpose dam construction. However decline of coefficient of flow duration was smaller than coefficient of river regime because coefficient of flow duration is less affected by maximum discharge and minimum discharge than coefficient of river regime, It was confirmed that multipurpose dam on upstream and midstream has a useful effect for improving the flow duration characteristics.

• Journal of the East Asian Society of Dietary Life
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• v.12 no.6
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• pp.554-565
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• 2002

The purpose of this study is to investigate the effect of raw Cassia tora L. powder added-diets on reducing cadmium accumulation in rats. The experimental animals were Sprague-Dawley family(♂, 4 weeks) which was classified into normal group CN, compared group CS, Cd-added group Cl and groups C2, C3, C4 in which 0.5, 1.0 and 1.5% of the Cassia tora L. powder are added, respectively. The growth rate and food efficiency ratio, and the amounts of accumulated cadmium in rats for S weeks were measured and analyzed. The results are as follows; 1. The rates of weight gain decreased in the order of C3>C2>C4>Cn>Cs>Cl groups, and Cl group to which only cadmium water had been fed was the lowest among them. The correlation between groups Cl and C3 was significantly different at the 1% level. 2. Food efficiency ratio(FER) decreased in the order of C3>C2>Cs>Cn>C4>Cl, and the FERs of C3, C2, CS, CN and C4 are greater than that of Cl by 22.87, 19.59, 18.54, 14.20 and 13.17%, respectively. 3. As for the Cassia tora L. powder-added groups, the amounts of cadmium accumulated in organs and tissues, that is, the brain, heart, spleen, liver, lungs, testicles. kidney, femoral muscle and leg bones were 0.45 $\pm$ 0.04 to 0.83$\pm$0.04, 1.68$\pm$0.02 to 2.16$\pm$0.02, 3.26$\pm$0.05 to 4.62$\pm$0.27, 37.52$\pm$0.09 to 47.71$\pm$0.73, 1.07$\pm$0.10 to 1.66$\pm$0.04, 1.04$\pm$0.06 to 1.24$\pm$0.08, 36.79$\pm$0.20 to 39.61 $\pm$0.53, 0.87$\pm$0.02 to 1.00$\pm$0.02 and 0.65$\pm$0.17 to 1.27 $\pm$ 0.06 $\mu\textrm{g}$/g, respectively. 4. The accumulated Cd content for C4 was the lowest among Cassia tora L. powder-added groups. When the results for C4 are compared with those for Cl, it is observed that each cadmium content accumulated in the brain, heart spleen, liver, lungs, testicles, kidney. femoral muscle and leg bones is dropped by 49.03, 22.56, 36.02, 35.75, 41.75, 36.20, 37.00, 22.77 and 56.67 %, respectively. On the other hand. the accumulated Cd content increased in the order of brain

• Korean Journal of Agricultural Science
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• v.8 no.1
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• pp.44-50
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• 1981

This experiments was carried out to evaluate the effect of nitrogen retention on different levels of crude protein intake according to live weight, and the crude protein and urea content in serum of the Korean native goat. The results obtained are as follows: 1. When the female goat at 8 months age (14kg) had taken nitrogen free diet, the content of endogenous urinary nitrogen was 1.29g and endogenous fecal nitrogen was 1.27g per day. Therefore, the goat needs minimum level of crude protein per day. 2. When the thermometer checked below-$10^{\circ}C$, the nitrogen retention rate showed minus reaction in spite of 20% crude protein level. This suggested that the low temperature was consumed higher energy to maintain the body. 3. The nitrogen retention rate of the pregnant female goat of 20kg live weight, however, decreased as compared with the growing goat and was 17~20%. 4. According to the levels of crude protein were lower, crude protein and urinary nitrogen contents in serum were greatly decreased.