• 대한수학회지
• /
• 제58권6호
• /
• pp.1501-1511
• /
• 2021

In this paper we study magnetic trajectories on ℍ³ × ℝ with respect to the strictly almost Kähler structure. We find three types of magnetic curves which correspond to the almost complex structure compatible to the product metric on ℍ³ × ℝ.

• Bulletin of the Korean Chemical Society
• /
• 제5권5호
• /
• pp.207-208
• /
• 1984

The tris(hydroxymethyl)aminomethane (Tris)-catalyzed hydrolysis of p-nitrotrifluoroacetanilide was kinetically studied. On the contrary to the previously reported results (R. M. Pollack and T. C.Dumsha, J. Am. Chem. Soc., 1973, 95, 4463), the dependence of the rate on [Tris] consists of an initial curve portion and a subsequent linear increase. This indicates that erroneous conclusions were made in the reported work due to the insufficient amount of data. The initial portions of the rate[Tris] profiles are attributed to the catalyzed breakdown of the tetrahedral intermediate, and the linear portions to the general base-catalyzed water attack at the substrate.

• 에너지공학
• /
• 제2권1호
• /
• pp.95-103
• /
• 1993

열전반도체를 이용한 소형열펌프의 개념 설계를 시도하고, 열역학적인 해석을 통하여 시스템의 성능을 예측하였으며 각 변수들이 시스템에 미치는 영향을 조사하였다. 일정한 조건 즉, $\mu$(=nν), J(=nI) 및 물의 유입 온도(Twi)가 주어졌을 때 대기의 온도 T$_{a}$ 가 증가할수록 성능계수와 냉방용량은 감소한다. 일정 냉방용량의 시스템을 설계하는 문제는 대기 온도와 물의 입구온도가 주어지면 $\mu$, J를 결정하는 문제로 귀결되며 기 제작된 열전소자를 사용한다면 v는 제작할 때 정해지므로 결국 n, ν, I의 최적 조합을 구하는 문제가 된다. 냉방용량 및 물의 온도가 주어졌을 때 $\mu$가 증가할수록 J가 증가하는 경향을 보인다. $\mu$-J 곡선과 최적 $\mu$값으로부터 최적 전류를 계산한다. 냉방 용량이 일정할 때 유량이 증가함에 따라 성능계수가 증가하며 COP$_{R}$ 증가의 경향은 대기온도가 낮을 수록 뚜렷하다. 흡열부보다 방열부의 열전달 계수가 시스템의 성능에 미치는 영항이 크다.

• Journal of Animal Science and Technology
• /
• 제46권4호
• /
• pp.503-508
• /
• 2004

본 연구는 돼지의 일령별 체중자료를 이용한 개체별 체중 성장곡선 추정을 통해 성장 특성을 조사하고 육질 형질과의 상관 관계를 규명하고자 실시하였다. 축산연구소의 재래돼지와 랜드레이스를 기초축으로 조성한 F2집단 253두를 대상으로 일령별 체중기록과 육질 형질을 측정하여 개체별 성장곡선 모수와 성장 특성치를 추정하고 등지방 두께, 조지방 함량, 지방율 및 전단력과 성장곡선 모수간의 표현형 상관관계를 추정하였다. 대부분의 성장 특성치들은 기존 연구에서 제시된 재래돼지와 랜드레이스순종의 중간정도 능력을 나타내었으며, 상관관계의 추정 결과 조숙성의 개체일수록 성숙체중이 작았으며 만숙성인 개체일수록 지속적인 성장률의 증가로 인해 변곡점이 나타나는 월령이 늦어지며 최대 증체율이 커지는 것으로 나타났다. 성장곡선 모수와 육질형질 측정치들간의 상관 관계는 암수간에 일부에서 다소 상반되는 방향으로 추정되었으며 특히 전단력의 경우 모든 성장 특정치들과의 관계가 반대로 추정되었다. 최대 증체율과 등지방 두께 및 조지방 함량과의 상관은 비교적 높은 정의 상관정도를 보여 최대 증체율이 클수록 등지방 두께와 조지방 함량이 높아지는 것으로 나타났다.

• 대한치과보철학회지
• /
• 제27권1호
• /
• pp.55-81
• /
• 1989

Recently the instantaneous center concept has been to understand the biomechanics by which a tissue derangement causes a mechanical derangement in human joint. Therefore, to understand the biomechanics of temporomandibular joint (T.M.J.) as a part of human joint, it is necessary to clarify the instantaneous center of rotation (I.C.R.) in the mandibular movement. Twenty male subjects without T.M.J. disorder and mandibular deviation during the mandibular movement were selected for this study. The habitual opening and closing paths were recorded on the paper of the sagittal metal plate by two pencil markers connected to the resin open clutch attached on the lower teeth, which was designed for this study. The coordinates of the 33-target points and the 109-anatomical landmarks were obtained using a Summagraphic digitizer connected to a 18AT computer. The original raw data of the opening and closing paths were smoothed by B-spline curve fitting technique and then the I.C.R. pathways were determined mathematically by the computer using algorithm for finding the I.C.R. of a planer rigid body model. Also the opening and closing movements of the mandible were simulated according to the determined I.C.R. The results obtained from this study were as follows. 1. At the early opening and the last closing, I.C.R's were almost distributed around the mastoid process outside the mandibular body without the presence in the region of the mandibular condyle. 2. The I.C.R. pathway showed variable patterns to each subject at the opening and closing movements. 3. The K constant with uniform pattern was obtained by the rotation angle times the radius, which was assumed to the index of the mandibular movement. 4. The opening and closing movements of the mandible were simulated by the I.C.R. pathways at the habitual opening and closing movements. 5. The mandibular condyle was rotated or translated accordng to the relative rotation angle and radius of the determinant factors of K contant.

• 한국전기전자재료학회논문지
• /
• 제19권1호
• /
• pp.18-22
• /
• 2006

Epitaxial aluminum nitride films on 6H-SiC (0001) were fabricated using reactive RF magnetron sputtering and post-deposition rapid thermal annealing. The electrical properties of AIN films depending on film thickness and measurement temperature have been observed. Full width at half maximum of AIN (0002) was $0.1204^{\circ}$ (about 430 arcsec) X-ray rocking curve results. The equivalent oxide thickness (EOT) of AIN film was estimated as about 10 nm and the leakage current density was within the order of $10^{-8} 4/cm^2$. The dielectric constant of AIN film estimated from the accumulation region of C-V curve measured at $300^{\circ}C$ was 8.3. The dynamic dielectric constant was obtained as 5.1 from J vs. 1/T plots at the temperature ranging from R.T. to $300^{\circ}C$ From above, estimation temperature dependance of the electrical properties of Al/AIN/SiC MIS devices was affirmed and useful data compilation for the reliabilities of SiC MIS is expected.

• Animal cells and systems
• /
• 제15권1호
• /
• pp.73-78
• /
• 2011

Estimating the habitat potential of inland forest patches for birds requires the modeling of species-area relationships, or relationships between habitat size and numbers of bird species in each patch. The accurate estimation of speciesarea relationships significantly reduces the effort required to recognize the number of species living in each patch. The objective of this study was to estimate the relationship between forest patch size and bird species diversity in Dangjin County, in northwest South Korea, based on the sizes of inland forest patches. KOMPSAT-2 images were obtained and ortho-rectified to construct a map of the target forest patches. The numbers of birds per patch were surveyed four times: August 2008, September 2008, February 2009 and May 2009. Regression models were derived to explain the relationships between the numbers of bird species and patch size. A model that was derived using data from all four observation periods had the highest coefficient of determination ($R^2$). According to these models, the numbers of bird species at first increased linearly with increasing patch size; however, the curve then plateaued. Our model including observations from four seasons will be useful for estimating the numbers of bird species in other inland forest patches in South Korea.

• 동력기계공학회지
• /
• 제12권5호
• /
• pp.40-47
• /
• 2008

The turbulent flow characteristics around a small-size axial fan(SSAF) for a refrigerator are strongly dependent upon the operating points. Four operating points such as $\phi$ =0.1, 0.18, 0.25 and 0.32 were adopted in this study to investigate three-dimensional turbulent flow characteristics around the SSAF by using a fiber-optic type Laser Doppler Anemometer(LDA) system. Downstream mean velocity profiles of the SSAF along the radial distance show that axial and tangential velocity components exist predominantly, except $\phi$ = 0.1, and have a maximum value at $r/R{\fallingdotseq}0.8$, but radial velocity component having a relatively small value only turns flow direction to the outside or the central part of the SSAF. The turbulent intensity shows that the radial component exists most greatly after $r/R{\fallingdotseq}0.5$. Downstream turbulent kinetic energy at $\phi$ = 0.25 and 0.32 together has the largest peak value at $r/R{\fallingdotseq}0.9$.

• Journal of Animal Science and Technology
• /
• 제45권4호
• /
• pp.509-516
• /
• 2003

한우 암소로부터 시간적인 간격을 두고 조사된 체중측정 기록에 대해 기존에 제안된 몇 가지 비선형의 성장곡선 모형을 적용하여 한우 암소의 성장모형을 추정하고, 추정된 성장모형의 모수를 이용하여 한우암소에 대한 성장특성을 규명하기 위해 실시하였다. 각 성장곡선 함수로 추정한 한우 암소 집단의 성장 곡선은 다음과 같다. Gompertz 모형 : $W_t=370.2e^{-2.208e^{-0.00327t}$ von Bertalanffy 모형 : $W_t=388.6(1-0.549e^{-0.00261t})^3$ Logistic 모형 : $W_t=341.2(1+5.652e^{-0.00524t})^{-1}$ 각 모형으로 전체자료를 이용하여 추정한 일반적인 성장곡선의 모수 A(성숙체중), b(성장비) 및 k(성숙률)와 추정된 모수들을 이용하여 변곡점 도달일령, 변곡점에서의 체중 및 변곡점에서의 일당증체량과 각 모형별 오차 제곱합 등을 계산하였는데, 세 모형 중 von Bertalanffy 모형이 성숙체중이 제일 크고(388.6kg), 변곡점 도달일령이 제일 빠르며(191일), 변곡점 도달시 체중이 제일 작고(약 115kg), 오차 제곱합도 제일 작았다(1,1170.9) 그리고 Logistic 모형이 성숙체중이 제일 작고(341.2kg), 변곡점 도달일령이 제일 늦으며(약 330일), 변곡점 도달시 체중이 제일 크고(약 170kg), 오차 제곱합도 제일 컸다(1,287.7). Logistic 모형이 세 모형 중에서 오차 제곱합이 제일 크고 생시와 36개월령에서 실측체중과 적합 체중간의 차이가 제일 큰 반면 von Bertalanffy 모형이 세 모형 중에서 오차 제곱합이 제일 작고 생시와 36개월령에서 실측체중과 적합 체중간의 차이가 제일 작은 결과를 볼 때, 본 연구 자료인 한우 암소의 성장은 von Bertalanffy 모형, Gompertz 모형 그리고 Logistic 모형 순으로 적합도가 좋은 것으로 판단된다.

• 한국가스학회:학술대회논문집
• /
• 한국가스학회 1997년도 추계학술발표회 논문집
• /
• pp.229-235
• /
• 1997

A low power (300 mW) catalytic bead combustible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 MJ/$m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas has a slightly different curve of sensitivity vs. sensor temperature. Thus there Is no temperature at which all sensitivities are equal. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.