• Carbon letters
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• 제11권2호
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• pp.90-95
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• 2010

Carbon materials such as graphite and graphene exhibit high electrical conductivity. We examined the electrical conductivity of synthetic and natural graphene powders after the chemical reduction of synthetic and natural graphite oxide from synthetic and natural graphite. The trend of electrical conductivity of both graphene (synthetic and natural) was compared with different graphite materials (synthetic, natural, and expanded) and carbon nanotubes (CNTs) under compression from 0.3 to 60 MPa. We found that synthetic graphene showed a marked increment in electrical conductivity compared to natural graphene. Interestingly, the total increment in electrical conductivity was greater for denser graphite; however, an opposite behavior was observed in nanocarbon materials such as graphene and CNTs, probably due to the differing layer arrangement of nanocarbon materials.

• Journal of Nutrition and Health
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• 제22권2호
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• pp.108-117
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• 1989

The purpose of this study was aimed to investigate the historical tends of population growth which has reflected direct effect of the ratio of food self sufficiency in Korea between the year of 1910 and 1980. Author divided the whole years between 1910 and 1980 into five different periods ; colonial period from 1910 to 1945, post colonial period from 1945 to 1950, Korean war period from 1950 to 1955, post Korean war period from 1955 to 1960, fast economic growing period 1960~1980. The ratio of national food self sufficiency has been profoundlly affected by dual factors ; rate of population group and increment of GNP which reflect the national economic development. Total food production never reached the level of population growth ratio in Korea. As a result food demand and supply has shown imbalaced condition which leads to import foods from outside contury to compensate food shortage. The increment of GNP sharply cut down the cereal consumption. The consumption of fish, milk, eggs and meat reflected to increase since 1970.

• KSTLE International Journal
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• 제1권1호
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• pp.63-68
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• 2000

Angular contact ball bearings are mainly used in the spindle, which requires high speed and stiffness. The heat generation is studied by experiments and simulations using a pair of angular contact ball bearings. The temperature variation of inner and outer races and the temperature increment distribution are measured by using thermocouples for the rotational speed, preload, viscosity of lubricant. The measured values from experiments are used to estimate the heat conduction rate. The method of oil-air lubrication is used for the experiment. The amount of conduction heat transfer to the test spindle and the convection heat transfer coefficients long the spindle are computed by using inverse method with temperature increment distribution. Total heat generation rate is estimated with the heat partition rate which is calculated from temperatures of inner and outer races. In addition, the empirical factor of oil-air lubrication method for Palmgren's heat generation model is suggested. The empirical friction coefficients, which are obtained from the experiments, depend on the preload condition, and can give us more accurate estimation of the heat generation in ball bearings.

• 한국식품영양과학회지
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• 제38권3호
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• pp.364-371
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• 2009

복숭아의 저장안정성 증가를 위한 연구의 일환으로 복숭아에 $0.5{\sim}2$ kGy의 저선량 감마선을 조사하여 $20^{\circ}C$에서 9일동안 저장하면서 복숭아의 미생물학적 및 이화학적 품질 특성을 살펴보았다. 복숭아의 총 호기성 세균과 효모 및 곰팡이의 변화는 조사선량에 따라 감소하여 감마선 조사가 미생물 저감효과를 가져오는 것으로 나타났다. 기계적 경도 측정결과 조사선량이 증가할수록 감소하였으며, 색도 변화는 감마선 조사에 의해 명도(L)가 감소하고, 적색도(a)와 황색도(b)는 증가하는 것으로 나타났다. pH, 가용성 고형물, 총 폴리페놀 함량, 항산화 활성 변화는 감마선 조사된 시료구가 비조사구에 비해 함량이 높게 나타났으며, 선량에 비례하여 증가하였다. 비타민 C(아스코르브산) 함량 변화는 조사선량과 저장기간에 비례하여 증가하는 경향을 나타내었으나 감마선 조사에 의한 영향을 나타나지 않았다. 관능검사 결과 비조사구에 비해 조사구에서 높은 기호도를 보였으며, 저장 기간이 지남에 따라 비조사구와 조사구(0.5, 1, 1.5 kGy)의 기호도는 유의차를 나타내지 않았다. 따라서 복숭아에 대한 저선량 감마선 조사는 복숭아의 색도, 물리적 특성에 좋지 않은 영향을 나타내지만, 미생물학적 안정성에 효과적이며 항산화능을 증진시키는 것으로 나타났다.

• 한국수산과학회지
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• 제29권2호
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• pp.191-196
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• 1996

부산 가덕도 연안에서 1990년 11월부터 1991년 10월까지 채집한 베도라치의 연령, 성장 및 산란을 조사하였다. 연령형질은 이석을 사용하였고, 윤문은 투명대에서 불투명대로 이행하는 경계로 하였다. 윤문 형성시기는 12월이었고, 년 1회 형성되었다. 산란기는 11월에서 12월로 추정되었고, 주산란기는 12월이었다. 따라서 초륜이 형성되기까지 소요되는 기간은 1.0년 으로 추정되었다. 베도라치의 성장식은 $L_t=33.64(1-e^{-0.1357(t+2.6853)})$, $W_t=414.11(1-e^{-0.1357(t+2.6853)})^{3.9745}$ 이었다.

• 한국운동역학회지
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• 제15권4호
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• pp.153-168
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• 2005

The purposes of this study were to determine the influence of midsole hardness and sole thickness of sports shoes on ball flex angle and position with increment of running velocity. The subjects employed for this study were 10 college students who did not have lower extremity injuries for the last one year and whose running pattern was rearfoot striker of normal foot. The shoes used in this study had 3 different midsole hardness of shore A 40, shore A 50, shore A 60 and 3 different sole thickness of 17cm, 19cm, 21cm. The subjects were asked to run at 3 different speed of 2.0m/sec, 3.5m/sec, 5.0m/sec and their motions were videotaped with 4 S-VHS video cameras and 2 high speed video cameras and simultaneously measured with a force platform. The following results were obtained after analysing and comparing the variables. Minimum angle of each ball flex position were increased with the increment of running velocity and shoe sole thickness(P<0.05), but mid-sole hardness did not affect minimum ball flex angle. The position which minimum angle was shown as smallest was 'D'. Midsole hardness and sole thickness did not affect time to each ball flex minimum angle, total angular displacement of ball flex angle, and total angular displacement of torsion angle(P<0.05). The position which minimum angle was appeared to be earliest was similar at walking velocity, and E and F of midfoot region at running velocity. Total angular displacement of ball flex position tended to increase as shifted to heel. It was found that running velocity had effects on ball flex angle variables, but shoe sole thickness partially affected. It would be considered that running velocity made differences between analysis variables at walking and running when designing shoes. Also, it was regarded that shoes would be developed at separated region, because ball flex angle and position was shown to be different at toe and heel region. It is necessary that midsole hardness and thickness required to functional shoes be analyzed in the further study.

• 한국산림과학회지
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• 제99권3호
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• pp.432-438
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• 2010

인공산성비 처리와 목초액 처리가 토양 화학적 성질, 인동덩굴(Lonicera japonica)의 뿌리와 엽내 이온함량 변화 및 생장에 미치는 영향을 알아보기 위하여 다양한 수준의 인공산성비(pH 5.6, 4.5, 3.5, 2.5)와 대조구(pH 6.3)로 구분하여 6월에서 10월까지 150일간 주 2회씩 총 30회에 걸쳐 처리하였고, 목초액을 500배로 희석하여 2주 1회씩 총 10회에 걸쳐 처리하였다. 인공산성비의 pH가 낮아질수록 토양 pH는 감소하였고, 유기물함량, 전 질소, 유효인산은 증가하는 경향이었지만, 목초액을 처리하였을 때 토양 개선효과는 미비한 것으로 나타났다. 식물체의 성분은 인공산성비 처리에 의해 $SO_4{^2}$와 $NO_3{^-}$가 증가하였으며 목초액 처리구에서는 증가 폭이 감소하였다. 또한 양이온은 인공산성비의 pH 에 따라 증가하는 경향이 나타났으며, 뿌리 보다는 잎에서 더 높게 나타났다. 인공산성비 처리 후 조기 낙엽과 생장저해가 나타났으나 목초액 처리 후 생장량이 증가하였다.

• 대한기계학회논문집
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• 제19권11호
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• pp.3022-3030
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• 1995

The irreversibility of condensation process in the supersonic flow of steam turbine cascade causes the entropy to increase and the total pressure loss to be generated. In the present study, in order to investigate the moist air flow in two dimensional steam turbine cascade made as the configuration of the last stage tip section of the actual steam turbine moving blade, the static and total pressures along suction side of the blade are measured by pressure taps and Pitot tube. The flow field is visualized by a Schlieren system. The effects of stagnation temperature and the degree of supersaturation on energy loss and entropy change in the flow are clearly identified.

• 생물환경조절학회지
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• 제18권4호
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• pp.420-424
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• 2009

고랭지 착색단고추 여름재배시 착과 증대 및 품질향상을 위하여 호박벌을 이용한 수정증대 효과에 대하여 검토하였다. 호박벌에 의하여 처리기간 동안 착과수의 증가는 있었으나 재배기간의 총 수량에서는 무처리와 비교하여 차이가 없었다. 과실의 종자수는 무처리에 비해 호박벌 처리에서 7.3%가 증가되었으나 배꼽썩음과 발생은 높았다. 과중의 분포 비율이 호박벌 처리에 의하여 SS 사이즈는 감소하고 L 사이즈가 증가하여 수출 규격품율이 향상되었다. 따라서 고랭지 여름재배시 착과증진을 위한 호박벌 처리는 착과율을 높이고 과실의 종자수를 증가시켜 수출 규격품율을 높이는 등 고품질 생산에 효과적이었으며 배꼽썩음과 방지에 대한 검토가 추후 필요할 것으로 판단되었다.

• 대한치과교정학회지
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• 제3권1호
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• pp.14-20
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• 1972

It is well known fact that physical growth and development of children are influenced by many factors. The importance of socio-economic, geographic and cultural background cannot be over-emphasized in the evaluation of general pattern of physical growth and development of children. In this study the author measured and studied the body height and body weight of children living in the region of mine and industry located in Young-Wol Kun, Kang-Won Do, for the purpose of exploring out the influence of socio-geographic factors to act on physical growth and development of children. Total number of samples were 4,147 comprising 2,170 in male and 1,977 in female with ages ranging from 7 to 15. 1) The growth curves showed that young males grow slowly by 14 years of age, here-after rapidly and the young females grow slowly by 12 years of age, rapidly by 13 years of age and slowly thereafter. 2) The annual increment curves of body height and body weight showed that the most increment of female occurs by 13 years of age and that of mate, by 15 years of age. 3) The growth curves of the male and female crossed twice. It shows the difference of the pattern of growth between the both sexes. 4) The standards for the children in this region were presented. 5) The time of changes of stndard deviation curves of body height and body wegiht coincided nearly with that of annual increment. 6) Body weight and body height .of the children is larger than that of Korean children before World War II, but smaller than that of standards of recent Korean.