• Title/Summary/Keyword: 임계온도

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Specific heat jump of superconducting crystal in low temperature (저온에서 초전도 결정의 비열 점프)

  • Kim, Cheol-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.1
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    • pp.1-5
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    • 2011
  • In this paper, firstly we have derived and presented the specific heat jump as a function of the critical temperature. Secondly, we have analyzed the sign and magnitude of the derived specific heat jump and predicted the expected experimental results. And lastly, we have compared the expected experimental results with the real experimental results. Theoretically derived specific heat jump is considerably compatible with the specific heat jump up and down phenomena of the $YNi_2B_2C$ crystal. Especially, the remarkable theoretical prediction-hat the specific heat would jump down during the normal state-to-superconducting state transition at extremely low temperatures-have been confirmed by the experimental results.

Growth mode of epitaxial $Si_{0.5}Ge_{0.5}$ alloy layer grown on Si(100) by ion beam assisted deposition (이온선보조증착에 의한 Si(100)기판에 정합성장된 $Si_{0.5}Ge_{0.5}$박막의 성장방식)

  • Park, Sang-Uk;Baek, Hong-Gu
    • Korean Journal of Materials Research
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    • v.5 no.3
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    • pp.297-309
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    • 1995
  • 본 연구에서는 이온선보조증착법에 의해 Si(100)기판위에 정합성장된 $Si_{0.5}$Ge_{0.5}$층의 핵성성과 성장을 고찰하였다. 성장층에 대한 AFM(Atomic Force Microscopy), RHEED(Reflection High Energy Electron diffraction) 등의 분석결과 Si(100)기판위에 이온선보조증착에 의하여 성장된 $Si_{0.5}$Ge_{0.5}$층은 Stranski-Kranstanov(SK)기구로 성장되며, 300eV, 10 $\mu$A/$cm^{2}$의 Ar이온선을 조사시키는 경우 결정성이 향상되었고, SK 성장 방식의 임계두께가 증가하였다. Ar 이온선 조사에 의해 MBE에 의한 정합성장온도(55$0^{\circ}C$-$600^{\circ}C$)보다 훨씬 낮은 20$0^{\circ}C$에서 정합성장이 가능하였으며, $x_{mn}$값은 10.5%로 MBE에 의한 정합성장시 보고된 $x_{mn}$ 값보다 낮았다. 이온충돌에 의해 발생한 3차원 island의 분해와 표면확산의 증가가 $Si_{0.5}$Ge_{0.5}$층의 성장에 현저한 영향을 미쳤으며, 이온충돌의 영향은 3차원 island의 생성보다 3차원 island의 분해가 더 안정한 낮은 증착온도에서만 관찰되었다.

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Fabrication and superconducting properties of Bi2212 Rutherford cables (대전류 통전용 Bi2212 러더포드 도체 제작 및 특성 평가)

  • Kim, Sang-Chul;Ha, Dong-Woo;Oh, Sang-Soo;Oh, Jae-Gun;Han, Il-Yong;Kim, Ki-Chang;Shon, Ho-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.296-296
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    • 2008
  • 대용량의 초전도 전력기기에 사용되는 도체는 일반적으로 대전류를 통전할 수 있는 도체를 필요로 한다. 특히 SMES와 같이 펄스적으로 운전하는 코일에서 도체의 전류 용량을 증가시키면서 동시에 교류손실을 줄이는 방법으로 도체를 제조하기 위해서는 여러 가닥의 소선을 꼬아서 만드는 러더포드 케이블로 제조할 필요가 있으며 이를 위해서는 소선이 원형 상태를 유지하고 있어야 한다. Bi-2212 고온초전도선은 유일하게 원형 상태에서의 응용이 가능하므로 이 선의 개발 및 케이블 공정 개발은 매우 중요하다. 본 연구에서는 Bi-2212 고온초전도 소선을 사용하여 Rutherford 케이링을 할 수 있는 장치를 개발하였으며, 이 장치를 이용하여 복합 다심의 Bi-2212 초전도 소선을 8본, 20본 그리고 30본의 Bi-2212 러더포드 케이블을 110 m 길이까지 가공하였다. 제조한 러더포드 케이블 시료를 열처리에서의 부분용융 온도를 변화시키는 것으로 열처리 조건을 연구하였고, 77K, 64K 그리고 4.2K에서 임계전류 특성을 조사하였다. 또한 초전도 소선의 미세 조직을 관찰을 통하여 초전도 특성을 향상시키고자 하였다. 그래서 30본의 Bi-2212 러더포드 케이블에서 4.2K 온도로 환산하였을 때 5000 A를 초과하는 특성을 얻을 수 있었다.

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The Free Energy of Mixing for a Binary Lattice Solution Consisting of Two Identical Interpenetrating Sublattices (두개의 동등한 상호침투 부격자로 구성된 이성분 격자 용액의 혼합자유에너지)

  • Jung, Hae-Young
    • Journal of the Korean Chemical Society
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    • v.66 no.4
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    • pp.278-283
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    • 2022
  • Using the Kirkwood's method, the free energy of a binary lattice solution consisting of two identical interpenetrating sublattices, such as a simple cubic lattice or a body-centered cubic lattice, was calculated up to the tenth order of the reciprocal of absolute temperature. Using this, liquid-liquid coexistence curves and critical solution temperatures for the binary lattice solutions were calculated to quantitatively investigate the effect of non-random mixing of molecules. And it was shown that the coexistence curve of the simple cubic lattice solution was in good agreement with the Monte-Carlo computer simulation result.

The Development and Oviposition of Bean Bug, Riptortus clavatus Thunberg (Hemiptera: Alydidae) at Temperature Conditions (온도조건에 따른 톱다리개미허리노린재의 발육 및 산란)

  • Bae, Soon-Do;Kim, Hyun-Ju;Park, Chung-Gyoo;Lee, Geon-Hwi;Park, Sung-Tae
    • Korean journal of applied entomology
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    • v.44 no.4 s.141
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    • pp.325-330
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    • 2005
  • This study was conducted to determine the effect of temperatures on the egg and nymphal development, adult longevity and oviposition of bean bug, Riptortus clavatus Thunberg, using Saealkong seed as food sources in fibrous nylon-tube at four different temperatures (20, 24, 28 and $32^{\circ}C$). Hatchability showed the highest value of 100% at $28^{\circ}C$ and decreased with increasing temperature. Egg duration ranged from 7 days at $32^{\circ}$ to 16.7 days at $20^{\circ}C$. Instar duration was longer with increasing instar stage. Nymphal duration was 38 days at $20^{\circ}C$, 30 days at $24^{\circ}C$, 23 days at $28^{\circ}C$, and 18 days at $32^{\circ}C$ Emergence rates to adult were 16, 41, 72 and 68% at 20, 24, 28 and $32^{\circ}C$, respectively. Female adult longelity ranged from a minimum 20 days at $20^{\circ}C$ to a maximum 63 days at $28^{\circ}C$, while the longevity of male ranged from 19 days at $20^{\circ}C$ to 60 days at $28^{\circ}C$. Preoviposition duration was shorter with increasing temperature and ranged from 11 days at $20^{\circ}C$ to 5 days at $32^{\circ}C$. Total number of eggs laid per female ranged from a minimum 21 eggs at $20^{\circ}C$ to a maximum 67 eggs at $28^{\circ}C$. Consequently, the estimated lower threshold tempeatures of each developmental stage were $10.3^{\circ}C$ for egg, and 9.3, 12.7, 10.0, 11.0 and 8.7 for the 1st, 2nd, 3rd, 4th and 5th instar, respectively.

The mathematical model of temperature dependent growth of Scuticociliate Miamiensis avidus in vitro and in vivo conditions (In vitro와 in vivo에서의 온도에 따른 스쿠티카충 성장의 수리 모델)

  • Oh, Chun-Young
    • Journal of fish pathology
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    • v.26 no.2
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    • pp.65-75
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    • 2013
  • Population growth equation of scuticociliate Miamiensis avidus was obtained from the experimental results of in vitro culture condition to estimate the growth rate and carrying capacity from the growth equation. In addition, intraperitoneal infections into olive flounder Paralichthys olivaceus were carried out into 2 different conditions: different concentrations of M. avidus in same water temperature and same concentration of M. avidus in different water temperatures. Olive flounder mortality was threshold dependent with both the temperature and M. avidus density parameters. In this paper, we propose a mathematical model to study M. avidus growth in olive flounder based upon the interactions between parasite and host. The mathematical model was logistic growth differential equation (1.2). The parameters were found with Matlab program through the Levenberge-Marquardt method. In theorem, equilibrium values between the infected fish population and dead population could found. Our equilibrium points were a stable equilibrium and an unstable equilibrium. From the equation (1.6), it was possible to predict the amount of cumulative mortality of olive flounder along with the time after M. avidus infection.

A Correlation Analysis between Land Surface Temperature and NDVI in Kunsan City using Landsat 7 TM/ETM+ Satellite Images (Landsat 7 TM/ETM+ 위성영상을 이용한 군산지역 지표 온도와 NDVI에 대한 상관분석)

  • Lee, Hong-Ro;Kim, Hyung-Moo
    • Journal of the Korean Association of Geographic Information Studies
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    • v.8 no.2
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    • pp.31-43
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    • 2005
  • Four time points of the fractional area data during the 15 years of the highest group of land surface temperature and the lowest group of NDVl of the Kunsan city Chollabuk_do, Korea located beneath the Yellow sea coast, are observed and analyzed their correlations for the intention to detect the changes of urban land cover. As long as the effective contributions of satellite images in the continuous monitoring of the wide area for wide range of time period, Landsat-5 TM and Landsat-7 ETM+ artificial satellite images, acquisited over the Kunsan city area, are surveyed by the compared calibration after quantization and classification of the deviations between TM and ETM+ images substituted approved error correction thresholds such as gains and biases or offsets. This experiment and research applied Landsat-5 TM and Landsat-7 ETM+ artificial satellite images in change detection of urban land cover in urbanized Kunsan city, then detected strong and proportional correlation relationship between the highest group of land surface temperature and the lowest group of NDVI which exceeded R=(+)0.9478, so the proposed Correlation Analysis Model between the highest group of land surface temperature and the lowest group of NDVI will be able to give proof an effective suitability to the land city change detection monitoring.

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Variation of Vapor Pressure Deficit and Condensation Flux of Air Heating Plastic Greenhouse Installed with Two Layers Thermal Curtain in Winter (이층커튼 온풍난방 플라스틱온실의 겨울철 포차 및 결로량 변화)

  • Lee, Hyun-Woo;Kim, Young-Shik;Sim, Sang-Youn;Lee, Jong-Won
    • Journal of Bio-Environment Control
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    • v.22 no.1
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    • pp.35-41
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    • 2013
  • This study was conducted to provide data necessary for reducing the condensation on greenhouse covering in winter season. The variation of VPD (Vapor Pressure Deficit) and condensation flux was analyzed in experimental tomato greenhouse. VPD values in experimental plastic greenhouse were greater than 0.2 kPa of disease prevention threshold, and lower than 0.5 kPa of threshold for dehumidification. The surface temperature of inside covering was slightly higher than the average temperature of outside and above curtain, and changed according to outside temperature. The humidity above curtain was nearly 100% and good condition for condensation. The humidity below curtain was 75~90% and comparatively stable condition for growing. The condensation flux value in experimental greenhouse corresponded with result of Seginer and Kantz (1986).

Effect of Temperature on the Development of Bracon hebetor (Hymenoptera: Braconidae) Parasitizing Indianmeal Moth (Lepidoptera: Pyralidae) (화랑곡나방(나비목: 명나방과)에 기생한 보리나방살이고치벌 (벌목: 고치벌과)의 발육과 온도와의 관계)

  • 김나경;나자현;류문일
    • Korean journal of applied entomology
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    • v.39 no.4
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    • pp.275-279
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    • 2000
  • Development of Bracon hebetor Say parasitizing Indianmeal moth (Plodia interpunctella (Hubner) was studied at five temperature conditions (17, 20, 25, 28 and 32$\pm$0.5$^{\circ}C$) under a photoperiod of 16 : 8 (L : D). Developmental period (mean$\pm$s.e.) of B. hebetor from egg to eclosion decreased from 28.6$\pm$0.50 to 9.3 $\pm$0.09 days and 28.1 $\pm$0.51 to 9.2$\pm$0.09 days for female and male, respectively, as the temperature increased from 17 to $32^{\circ}C$. The combination model provided a good description of the relationship between temperature and development. The low temperature thresholds were estimated to be 14.0, 12.8, 15.1$^{\circ}C$ for development of egg, larva and pupa. The thresholds for normal development (outside of the boundary layer of the development) were 14.0, 17.5, $15.1^{\circ}C$ for egg, larva and pupa, respectively, indicating that the larval stage is more sensitive to the low temperature than the other stages. The results suggested that the present B. hebetor population could be another ecological race adapting to the seasonal temperature conditions of this area.

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Modelling the Effects of Temperature and Photoperiod on Phenology and Leaf Appearance in Chrysanthemum (온도와 일장에 따른 국화의 식물계절과 출엽 예측 모델 개발)

  • Seo, Beom-Seok;Pak, Ha-Seung;Lee, Kyu-Jong;Choi, Doug-Hwan;Lee, Byun-Woo
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.18 no.4
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    • pp.253-263
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    • 2016
  • Chrysanthemum production would benefit from crop growth simulations, which would support decision-making in crop management. Chrysanthemum is a typical short day plant of which floral initiation and development is sensitive to photoperiod. We developed a model to predict phenological development and leaf appearance of chrysanthemum (cv. Baekseon) using daylength (including civil twilight period), air temperature, and management options like light interruption and ethylene treatment as predictor variables. Chrysanthemum development stage (DVS) was divided into juvenile (DVS=1.0), juvenile to budding (DVS=1.33), and budding to flowering (DVS=2.0) phases for which different strategies and variables were used to predict the development toward the end of each phenophase. The juvenile phase was assumed to be completed at a certain leaf number which was estimated as 15.5 and increased by ethylene application to the mother plant before cutting and the transplanted plant after cutting. After juvenile phase, development rate (DVR) before budding and flowering were calculated from temperature and day length response functions, and budding and flowering were completed when the integrated DVR reached 1.33 and 2.0, respectively. In addition the model assumed that leaf appearance terminates just before budding. This model predicted budding date, flowering date, and leaf appearance with acceptable accuracy and precision not only for the calibration data set but also for the validation data set which are independent of the calibration data set.