• 한국지반신소재학회논문집
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• 제10권4호
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• pp.113-121
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• 2011

지중송전관로의 되메움재로는 보통 강모래를 사용하고 있다. 그러나 강모래의 열저항률은 습윤시 $150^{\circ}C$-cm/Watt 정도이고 건조시에는 이보다 2배 이상의 값을 나타낸다. 연구의 최종목표는 함수비 변화에 따라 열저항률의 변화가 작은 재료(습윤시 열저항률 $50^{\circ}C$-cm/Watt, 건조시 열저항률 $100^{\circ}C$-cm/Watt를 목표로 함)의 개발이나, 이 연구에서는 강모래를 포함한 각종 되메움재 후보군에 대하여 함수비, 건조단위중량, 입도분포 등의 차이에 따른 열저항 특성을 탐침법에 의해 조사하고, 시험결과를 비교 분석하였다. 분석 결과, 열저항 특성은 단위중량의 변화, 건조상태의 경우 최적함수비의 상태를 그대로 대기 중에 건조시킨 경우와 최초의 건조 상태에서의 열저항률의 차이 등을 고려하여야 하는 것으로 나타났다. 또한 최대밀도가 되도록 입도분포가 개선된 혼합재료는 원재료에 비해 열저항률을 크게 낮출 수 있는 것으로 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권9호
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• pp.1278-1284
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• 2000

An experiment was performed to evaluate different methods for preserving shrimp by-products and to determine their chemical composition. In the first experiment three ratios of shrimp by-product (SBP) to molasses (6:1, 4:1 and 3:1, wet weight), and to cassava root meal (3:1, 2:1 and 1:1, wet weight of shrimp by-product and air-dry weight of cassava root meal) were investigated. The pH of the SBP ensiled with molasses at a ratio of 3:1, and with cassava root meal at a ratio of 1:1, decreased during the first week to below 4.5 and remained low up to day 56 of ensiling, whereas the pH of the mixtures with higher ratios of SBP remained above 7.0, and the material deteriorated rapidly. The dry matter decreased initially in all treatments but then increased slightly from day 28 in the treatment where shrimp by-product was ensiled with cassava root meal at a ratio of 1:1. The crude protein (CP) and ammonia-N $(NH_3-N)$ contents of the preserved shrimp by-product material ensiled with molasses at a ratio of 3:1 increased significantly one week after ensiling. The CP content then remained constant, while the $NH_3-N$ concentration continued to increase up to 56 days after ensiling. When SBP was ensiled with cassava root meal at a ratio of 1:1 the CP content of the silage increased significantly up to 21 days after ensiling and then decreased back to the original level after 56 days, whereas $NH_3-N$ increased markedly up to 14 days and then remained fairly constant up to 56 days. However, the $NH_3-N$ content was significantly higher when SBP was ensiled with cassava root meal than with molasses. A balance experiment was carried out, arranged as a double Latin-square and including 6 F1 (Large White ${\times}$ Mong Cai) castrates fed randomly one of three diets based on cassava root meal, rice bran, and fish meal (FM) or shrimp by-product ensiled with molasses (SBEMO) or with cassava root meal (SBECA) as the main protein source. Apparent organic matter and CP digestibilities were significantly (p<0.001) higher for the fish meal diet than for the two shrimp by-product diets, although CP digestibility in SBEMO and SBECA was similar (p>0.05). N-retention was significantly higher for the fish meal diet than for the SBEMO diet, which in turn was significantly higher than for the SBECA diet (p<0.01). It can be concluded that shrimp by-product can be preserved by ensiling with molasses at a ratio of 3:1 or with cassava root meal at a ratio of 1:1. Nutrient digestibility and N-retention of diets based on these shrimp by-product silages were lower than for similar diets based on fish meal, probably due to their high chitin content and inferior amino acid balance.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 추계국제학술대회
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• pp.57-69
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• 2003

It is well known that many pesticides possess hormonal activity, and affect the developments of wildlife and mammals including human. Currently, pyrethroid insecticides are in worldwide use to control in and outdoor pests, providing potential far environmental exposure. Hormonal activities of these pyrethroid insecticides, however, have been little studied, and the developmental effects of them were no reported. Therefore, we firstly examined the potential estrogenic activities of some pyrethroid insecticides (permethrin, cypermethrin, tetramethrin, deltamethrin, sumithrin, fenvalerate and bioallethrin) by immature rat uterotrophic assay, luciferase reporter gene assay and Calbindin-D$\sub$9k/ (CaBP-9k) gene expression assay. Uterine wet weights were increased by permethrin and the permethrin-induced weights were inhibited by ICI 182780 in the uterolrophic assay. On the other hand tetramethrin significantly reduced uterine and vaginal wet weights, and also inhibited the E2-induced weight increases at all doses tested. Cypermethrin and sumithrin had a tendency to increase uterine weights, although not statistically significant. Permethrin and cypermethrin dose-dependently increased the luciferase activity in reporter gene assay. Northern blot analysis showed that permethrin induced CaBP-9k mRNA expression whereas tetramethrin inhibted. Subsequent studies were conducted to investigate the possible developmental effects of four pyrethroid insecricides (permethrin, cypermethrin, sumithrin and teramethrin). Either diethlbestrol (DES) or 17${\beta}$ -estradiol (E2) was used as a reference control in this study. Pyrethroid insecticides were administered to Sprague Dawley rats via subcutaneous injection at 6 to 18 days of gestation or 1 to 5 days after birth. In utero treatment of permethrin (10mg/kg/day) in female rat resulted in significant increases in uterine and ovarian weights while significant decreases in serum E2 concentration, uterine and ovarian ER${\alpha}$ mRNA levels. Sumithrin and permethrin led to acceleration in vaginal opening of female rat, while delay in preputial separation of male after neonatal treatment. Anogenital distances of PND 18 were significantly reduced in sumthrin-treated, and permerhrin-treated male rats after neonatal treatment. All the pyrethroid insecticides tested caused significant increases in uterine weights on PND 18, while significant reductions in the first diestrus phase when neonataly treated. In addition, exposure to pyrethroids in neonatal period led to significant reduction in relative brain weight in female rat on PND 18, but its weight was recovered in diestrus phase. In summary, Our experimental data demonstrate the possibilities of developmental effects of pyrethroid insecticides via estrogenic or antiestrogenic activity.

• 분석과학
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• 제19권3호
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• pp.244-254
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• 2006

난연제는 불길이 확산하거나 초기에 발생하는 것을 억제하는 물질을 의미한다. 난연제로 사용하는 이중 브롬계 난연제인 PBDEs는 갑상선 호르몬 붕괴와 내분비계 교란을 유발하는 물질이다. 본 연구에서는 PBDEs의 분석을 위한 적절한 전처리 방법을 제안하였고, 어류와 패류 포함 총 8종과 서울과 제주 모유 각 20개를 대상으로 BDE-28, 47, 99, 100, 153, 154 및 183의 인체 내 축적 수준을 조사하였다. PBDEs 분석을 위한 전처리 방법으로는 어패류의 경우 알칼리 분해 추출법을 적용하는 것이 적합한 것으로 확인되었다. 다층 실리카겔 컬럼 정제는 50 mL의 헥산을 이용하여 방해물질을 제거한후, 100 mL의 헥산:디클로로메탄(9:1)로 용출시키는 것이 적합한 것으로 확인되었다. 활성탄 정제 과정은 100 mL의 헥산:디클로로메탄(3:1)으로 용출시키는 것이 적합한 것으로 확인되었다. 어패류를 대상으로 한 실험에서 광어는 습식 중량 기준 890 pg/g이 검출되어, 시료 중 가장 높은 PBDEs 축적 정도를 보였다. 생태는 40 pg/g이 검출되어 시료 중 PBDEs의 축적 정도가 가장 낮은 것으로 나타났다. 모유 시료에서는 서울과 제주 지역에서 지방 중량 기준 2,580 및 3,600 pg/g이 검출되었으며, BDE-153과 183은 모두 검출되지 않았다. 재산과 초산의 경우 3,200 및 3,000 pg/g으로 큰 차이가 없는 것으로 나타났다. 본 연구에서 진행한 어패류 및 인체시료에서의 PBDEs 축적 정도를 파악한 결과, 외국에서 보고한 농도에 비해 낮은 수준을 유지하고 있음을 확인할 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제17권2호
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• pp.20-25
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• 1989

This study was carried out in order to investigate the treatment effect of PEG soln which is a common dimensional stabilizer to green log. sawing panel etc, on bonding product including plywood widely-used in secondary processing unit. The 30% concentration of aqueous PEG soln. with molecular weight of 400, 1.000 and 4,000 were prepared respectively, and also dipping the veneer in the PEG soln. spreading the PEG soln. on veneer and mixing the PEG soln. in the adhesive were allowed. Then the ratio of PEG impregnation on veneer, the adhesive strength of plywood were epitomized as follows: The ratio of impregnation by PEG 4,000 at dipping condition was highest. while that by PEG 400 at same condition was lowest. However, the effect of PEG molecular weight on the ratio of impregnation at spreading condition did not occur. 2. The adhesive strength was great in the order of 4,000>400>1,000 in molecular weight of PEG at dipping and spreading conditions. In case of mixing the PEG soln. in the adhesive, the adhesive strength was great in the order of 400>1,000>4,000 in molecular weight of PEG. Throughout three treatment conditions, PEG 400 was relatively favourable with about 10kg/$cm^2$ dry strength. 3. The adhesive strength was great 10 the order of spreading >dipping >mixing condition. 4. Although adhesive strength with the 30% concentration of aqueous PEG soln. was decreased by 35% and over, compared to control (non-treatment) adhesive strength, all types of PEG treatment except mixing the PEG soln. in the adhesive exceeded the standard dry strength for common use panel. 7.5kg/$cm^2$. 5. In warm water-proof test, the adhesive strengths by all PEG treatment conditions were less than the standard wet strength, 7.5kg cot, and also delamination of glue line occured mostly in mixing in the PEG soln. in the adhesive condition.

• Ocean and Polar Research
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• 제25권1호
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• pp.31-40
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• 2003

In August-September 2001, 15 samples of bottom sediments were collected in the inner, middle and open parts of Amursky Bay near Vladivostok, Russia, and barfin plaice Pleuronectes pinnifasciatus was sampled from the inner and the middle locations of the bay. In the sediments from all three sites elevated concentrations of several heavy metals, i.e. Zn ($102-115{\mu}/g$ dry weight), Ni $(70-73{\mu}g/g)$ and Cu $(27-35{\mu}g/g)$ were discovered. The contents of oil hydrocarbons were very close to or slightly higher than the maximal normal environmental background level, $100{\mu}g/g$ dry weight. The sediments contained negligible amounts of hexachlorocyclohexane, while DDT concentrations were quite high (1.7-16.3ng/g dry weight). Generally, there were no substantial differences in the pollution levels of the locations studied and our results resembled those reported for Amursky Bay in the 1990s. Surprisingly, in 2001 'fiesh' DDT comprised 70-85% of the total DDT content in sediment from all the locations studied. In fish liver total DDTs concentrations were 212.8 and 122.54 ng/g wet weight for the inner and the middle locations, respectively, and 'fresh' DDT comprised 35 and 64% of DDTs, respectively. These results provide evidence of recent input of DDT from an unknown source into the ecosystem of Amursky Bay. Histopathological changes revealed in the plaice liver (vacuolization of hepatocytes, coagulative necrosis of hepatocytes, inflammatory reaction, and necrosis of epithelial cells of bile ducts) are probably connected with an intensive metabolism of DDT in the fish organism. No histological and histomorphometric differences were found in the state of the interrenal tissue. Similar condition of the liver and the interrenal tissue in barfin plaice sampled from the inner and the middle locations of Amursky Bay may be explained by the absence of great differences in the pollution levels of these sites.

• Journal of Nutrition and Health
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• 제28권1호
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• pp.5-14
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• 1995

The present study was performed to investigate the effect of cereal fiber on lipid concentration of liver and serum in rats. Male Sprague-Dawley rats weighing 180$\pm$4g were divided into five groups by completely randomized block design : R, BR, B, W, and F. Each group fed a diet containing 0.7% cholesterol and a kind of cereal among rice(R), brown rice(BR), barley(B), whole wheat(W), and wheat flour(F) for 5 weeks. The results were summarized as follow : 1) Food intake. weight gain and feed efficiency ratio were not significantly different among the groups. 2) Fecal wet weight and dry weight were significantly higher in W group which fed the most amount of IDF(insoluble dietary fiber). 3) The weight of large intestine was significantly heavier in the W group compared to the others. But the weights of liver, stomach and small intestine were not significantly different among the groups. 4) Total lipid. triglyceride(TG) and total cholesterol(TC) content in liver were significantly different among the groups. The values were the lowest in the B group whose intake of SDF(soluble dietary fiber) was the highest 5) TC content in serum was not significantly different among the groups. TG content in serum was significantly lower in the rest groups than in the R group. HDL-c and free-c content in serum were significantly higher in the B group than in the rest groups. HDL-c/LDL-c, free-c/ester-c ratio were the highest in the B group but not significant. Above results show that the dietary fiber contained in cereals has physiological effects and they are different depending on fractions, IDF and SDF.

• Asian-Australasian Journal of Animal Sciences
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• 제21권11호
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• pp.1576-1584
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• 2008

In this study, canonical correlation analysis (CCA) was applied to estimate the relationship between three different sexual maturity traits (X set: days to first egg (DFE), weight of the first egg (WFE), body weight at first egg (BWFE)) and level of nutrient intake (Y set: energy (EI) and protein intake (PI)) or the egg production traits at two different periods (Z set: number of egg (NE1 and NET) and weight of egg (WE1 and WET) from 22 to 25 (Wfirst) and 22 to 33 wk of age (Wall), respectively), which were measured from 64 egg-type pullets (Isa Brown) manipulated for time of access to energy and protein sources to onset of egg production. Partial CCA (PCCA) was used to eliminate the contribution of differences in the levels of nutrient intake to canonical variables for X and Z sets at the first production period. Estimated canonical correlation coefficients between X set and Y set (0.429, p = 0.042), X set and Z set (0.390, p = 0.007 for Wfirst) and within Z set (between Wfirst and Wall; 0.780, p<0.001), and partial canonical correlation coefficient between X set and Z set (0.415, p = 0.009) were significant. Canonical weights and loadings from CCA indicated that the BWFE had the largest contribution compared to the DFE and WFE to variation of egg number produced at two different periods. The results from PCCA indicated that the contribution of PI and EI to the degree of the correlation between canonical variables for X and Z sets were unfavourable. In conclusion, the effect of body weight at sexual maturity upon the availability of nutrients can have a higher contribution to variation of egg production in pullets if the contribution of differences in nutrient intakes to onset of egg production were eliminated.

• Journal of Biosystems Engineering
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• 제18권4호
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• pp.344-350
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• 1993

The purpose of this study is to develop design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage. The main results of this study are as follows. 1. A wheel-lug ought to receive a special resistance in downward direction which resists the lug's upward motion on wet sticky soil surface. The authors introduce a new academic name of the "lift resistance(上昇抵抗力, 상승저항력)" for such a force which resists retraction of a wheel lug from the soil in the upward trochoidal motion. This force is composed of the frictional force acting on the trailing and the leading lug side, and the "perpendicular adhesion(鉛直付着力, 연직부착력)" acting on the lug face and the undertread face on adhesive soil. 2. The "lift resistance ratio(上昇抵抗力係數, 상승저항력계수)" and the "perpendicular adhesion ratio(鉛直付着力係數, 연직부착력계수)" were defined, which are something similar to the definition of the motion resistance ratio, the traction coefficient, etc. 3. The design equation of the optimum weight of a rotary tiller mounted on the tractor derived by calaulating the forces acting on the rotary blades. 4. The design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage were derived. It becomes clear that the optimum weight of a rotary tiller and a tractor can be estimated in planning design by means of putting about 21 design factors of the target into the equation. These equations are useful for planning design to estimate the optimum dimensions and specifications of a rotary tiller as well as a tractor by the use of known and/or unknown design parameters.

• Journal of Nutrition and Health
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• 제14권4호
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• pp.162-174
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• 1981

Fiftysix male weanling rats of the Sprague-Dawley strain weighing $52.6{\pm} 0.9g$ were fed with 77% starch-15% casein diet by ad libitum for four days to get them adapted and divided into eight groups. For three weeks, the body weight gain of rats was controlled in three different ranges. After the period of food restriction, the rats were recovered by being fed by ad libitum for seventeen days. During the experimental period, the amount of food intake and body weight were measured. And the experimental groups were compared when they reached at the same age and at the same body weight. Anterior Tibialis, Extensor Digitorum Longus, Soleus, Plantaris, Gastrocnemius were used as analytic items of skeletal muscle. Wet weight of muscle, muscle protein, water content were measured from each of five skeletal muscles. Sodium, potassium, magnesium content were measured from Anterior Tibialis, Extensor Digitorum Longus, Soleus ana Plantaris. Phosphorus was measured only from Gastrocnemius. The whole carcass protein except the skeletal muscles was also measured. During the period of food restriction, food intake was $311.7{\pm}19.5g$ for the control group. $130.2{\pm}1.5g$ for the second group and $161.7{\pm}2.1g$ for the third group. During the period of food restriction, body weight gain was $106.8{\pm}12.7g$ for the control group, $3.6{\pm}2.1g$ for the second group and $18.9{\pm}3.3g$ for the third group. Comparing the body weight when they reached at the age 66 days, the control group showed higher value than the other groups. In the concentration of electrolytes of skeletal muscles sodium and magnesium tend to increase and potassium and phosphorus tend to decrease by food restriction. But after their recovery, there was no significant difference between the groups. By the degree of food restriction, there was time difference in reaching at the same body weight. But when they reached at the same body weight, there was no significant difference in the value of electrolytes concentration. Regarding all the results of this study, the ages of rats which reached the same body weight were different by food restriction level during weanling. Once food·restricted rats reached the same body weight by recovery, the concentration of electrolytes and protein tend to become almost the same.