• 한국잡초학회지
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• 제15권3호
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• pp.183-187
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• 1995

갯드렁새 종자의 저장조건별 발아특성을 조사하여 연중 균일한 종자의 발아율을 유지시키면서, 이들을 방제할 수 있는 약제의 개발을 위한 실험종자로 이용하고자 일련의 실험을 수행한 결과는 다음과 같다. 1. 종자의 발아유기에는 저온습윤처리가 효과적이었으며 1개월 처리시 80% 이상의 종자가 발아되었다. 2. 실온건조저장된 종자는 2주일간의 저온습윤 처리로 70% 이상이 발아되었다. 3. 갯드렁새 종자의 발아율은 항온조건 보다 변온조건에서 높았으며 최적 발아온도는 35/$25^{\circ}C$의 변온조건이었다. 4. 갯드렁새 종자는 강피에 비하여 내염성이 현저하게 높았다. 강피는 0.5%의 NaCl 농도에서 거의 발아되지 않았으나 갯드렁새는 1.0%에서도 60% 이상의 발아율을 나타내어 간척지에서의 발아에 보다 유리하였다.

• 한국어류학회지
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• 제23권2호
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• pp.145-149
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• 2011

인위적 수온변화에 의한 미꾸라지 피부의 점액세포 반응을 확인하기 위해 고온($32^{\circ}C$)과 저온($4^{\circ}C$)에 적응시킨 실험군의 표피조직을 실온($18^{\circ}C$)의 대조군 집단과 비교 분석하였다. 그 결과, 고온적응 설험군에서는 대조군과 유의한 차이를 보이지 않았으나, 저온적응 실험군에서는 등, 체측, 후두부의 점액세포 수와 크기가 현저하게 증가하는 경향을 보였다(P<0.01). 또한 저온적응 실험군의 수온을 증가시켜 상온에서 재 적응시킨 결과에서도 피부 정액세포의 수와 크기가 현저히 감소하는 경향을 보였다(P<0.01). 따라서 미꾸라지 피부의 점액세포가 저온에 매우 민감하게 반응하는 양상은 어류의 조직학적 환경지표로서 유용할 것으로 여겨진다.

• 대한기계학회논문집B
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• 제33권3호
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• pp.164-169
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• 2009

The slip velocity and the temperature jumps for low-speed flow in microchannels are investigated using Langmuir slip boundary condition. This slip boundary condition is suggested to simulate micro flow. The current study analyzes Langmuir slip boundary condition theoretically and it analyzed numerically micro-Couette flow, micro-Poiseuille flow and grooved microchannel flow. First, to prove validity for Langmuir slip condition, an analytical solution for micro-Couette flow is derived from Navier-Stokes equations with Langmuir slip conditions and is compared with DSMC and an analytical solution with Maxwell slip boundary condition. Second, the numerical analysis is performed for micro-Poiseuille flow and grooved microchannel flow. The slip velocity and temperature distribution are compared with results of DSMC or Maxwell slip condition and those are shown in good agreement.

• 한국정밀공학회지
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• 제13권10호
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• pp.62-70
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• 1996

We experimented on cutting characteristics-cutting force, behavior of cutting temperature, surface roughness. chip thickness under low temperature, which generated by liquid nitrogen(77K). The work-pieces were freezed to-195 .deg. C and liquid nitrogen was also sprinkled on cutting area in order to decrease an experimental error of machining in low temperature. The workpiece was became to -195 .deg. C in5 minutes. In cooled condition surface roughness of workpiece was better than normal condition. In addition, we investigated the possibility that surface roughness of workpiece and cutting force can be predicted analyzing cutting conditions by the trained neural network.

• 한국건축시공학회지
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• 제2권2호
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• pp.151-156
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• 2002

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods for resolve these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerators for freezing resistance. In this study, we investigate the effect on strength development of cement mortar using accelerators for freezing resistance with the variance curing condition. As the result of this study, the mortar using accelerators for freezing resistance show that continuously strength development in curing condition of -5$^{\circ}C$. And compressive strength under the variance temperature condition was higher than constant temperature condition in same maturity.

• 한국연소학회지
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• 제10권4호
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• pp.24-32
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• 2005

Various types of plasma source applied in $CH_4$ decomposition process are compared. DBD by pulse and AC power, spark by pulse and AC power, rotating arc and hollow cathode plasma are chosen to be compared. The results show that $CH_4$ conversion per given unit power is relatively high in hollow cathode plasma and rotating arc that induces rather high temperature condition and that is why both thermal dehydration and plasma induced decomposition contribute for the overall process. In case of DBD wherein high temperature electron and low temperature gas molecule coexist, the process shows low conversion rate, for in rather low temperature condition the contribution of thermal dehydration is lowered. Selectivity of $C_2H_6$ and $C_2H_2$ is shown to be a good parameter of the relative contribution of plasma chemistry in the overall process. From the results we concluded that required condition of plasma source for a cost effective and high yield $CH_4$ decomposition is to have characteristics of both thermal plasma and non thermal plasma in which temperature is high above a certain threshold state for thermal dehydration and electron induced collision is maximized in the same breath.

• 한국약용작물학회지
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• 제23권5호
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• pp.370-378
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• 2015

Background : Aruncus dioicus var. kamtschaticus, functional wild vegetable, is perennial herb and young leaves with soft texture are generally used as edible food. So the demand for the vegetable has increased recently. This study was carried out to determine the effects of temperature and shading on germination characteristics of A. dioicus. Methods and Results : The experiment was performed by temperature and shading treatments. Seed pre-treatment before the germination experiment was carried out by the storage in low temperature ($4^{\circ}C$) under wet condition (LTW) for 0, 15, 30, 45 and 60 days and shading treatment were 35%, 50%, and 75% under control, BA (6-benzyladenine) and $GA_3$ (gibberellic acid) condition for 24 hours. Increasing the length of the storage periods led to increases seed germination percent in low temperature ($4^{\circ}C$) under wet condition (LTW), germination rate of A. dioicus seed was the highest at $15^{\circ}C$ with 60 days of seed pre-treatment. In the case of seeds pre-treatment with LTW, the more temperature went up, the more days to 50% of Germination of Final Germination Rate ($T_{50}$) went down. As a result of surveying shading treatment, germination rate was the highest in control of 35% shading and the next higher was in control of 50% shading. Conclusions : It is concluded that the temperature and shading are important factors to produce A. dioicus. Also, We suggest these results as basic data of A. dioicus for sexual propagation.

• Tribology and Lubricants
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• 제8권1호
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• pp.48-55
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• 1992

The friction characteristic of plastics (PTFE, Nylon, Acetal and phenolic) was studied on the lubricated condition with a pin on disk machine. Mineral oil without additive (base oil) and water were used as liquid lubricants at the controlled temperature. From the experimental work, it was found out that the coefficient of friction of plastics was controlled by the mechanical properities of plastic more than that of liquid for various load and temperature. Viscosity of liquid has affected on the friction only at low temperature under lighb load. Among the tested plastics, the coefficient of friction of PTFE was the lowest under light load and at low temperature while Nylon at medium load and temperature, and Acetal at heavy load and high temperature. The coefficient of friction of soft plastics like PTFE and Nylon were increased as the load and temperature were increased, while that of hard plastic (Acetal) was decreased and that of thermo setting plastic (phenolic) was mixed. Also for soft plastics, the coefficient of friction under heavy load was always higher than that under light load, while hard plastic was vice versa.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.608-613
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• 2013

In this paper, the low-temperature sintering of $TiO_2$ is approached to solve the problem of high temperature sintering which decreases the interconnection between particles or between substrate and particle. $TiO_2$ paste is prepared with Titanium (IV) isopropoxide as the precursor material and calcinate at different conditions (low temperature). In the results, since the changing of temperature and time of sintering, crystalline phase do not change and the intensities of anatase, rutile phase are higher. At $110^{\circ}C$, 7 h sintering condition, crystalline size of anatase and rutile phase are the smallest which are 13.07 and 17.47 nm, respectively. In addition, the highest zeta potential is about 32.77 mV and the repulsive force increases thus leading to the best of the dispersion characteristics between $TiO_2$ particles. Futhermore, DSSCs at that condition exhibits the highest efficiency with the values of $V_{oc}$, $J_{sc}$, FF and ${\eta}$ are 0.69 V, $8.60mA\;cm^{-2}$, 67.93% and 4.06%, respectively.

• International Journal of Industrial Entomology and Biomaterials
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• 제47권1호
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• pp.44-50
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• 2023

The Daehwangjam has excellent marketability and quality. However, precise silkworm breeding data on the recent high-temperature environment is not enough collected, and it is necessary to check whether stable Daewhangjam silkworm egg production was possible in poor environments. In this study, the timing of metamorphosis of the Daewhangjam parents Jam323 and Jam324 silkworms, in an optimal condition and a general condition similar to breeding grounds, was investigated to confirm that appropriate mating was achieved. Surprisingly, a number of female moths were discarded due to the metamorphosis of Jam324 female moths much earlier than Jam323 male moths in either an optimal or a general condition. To improve this, during the Jam324 female pupation period, the mild low-temperature of 15℃ was treated for the pupation period to delay the metamorphosis into female moths. Depending on the treatment period, the metamorphosis of the female pupa was delayed by more than 4 days, allowing normal mating with the Jam323 male moth. The eye pigments in a pupa also slowly accumulated in these treatments. In order to discover the side effects of low-temperature treatments, the voltinism of the Daewhangjam eggs was investigated, but most of them remained univoltine. Taken together, the low-temperature treatment during the female pupation period made it possible to use Jam324 female moths that were should be discarded, which means that stable and efficient management of Daewhangjam egg production is possible.