• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.175-180
• /
• 2001

In this study, the minimum heat flux conditions are experimentally investigated for the spray cooling of hot plate. The hot plates are cooled down from the initial temperature of about $900^{\circ}C$, and the local heat flux and surface temperatures are calculated from the measured temperature-time history. The results show that the minimum heat flux point temperatures increase linearly resulting from the propagation of wetting front with the increase of the distance from the stagnation point of spray flow. However, in the wall region, the minimum heat flux point temperature becomes independent of the distance. Also, the experimental results show that the velocity of wetting front increases with the increase of the droplet flow rate.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2003년도 생물공학의 동향(XIII)
• /
• pp.446-450
• /
• 2003

T.f. 및 T.t. 박테리아의 흡착정도와 침출효율 간에 선형적인 비례관계는 관찰되지 않았다. 동일 배양균에서 재생로의 분진 즉 기질입자의 크기가 감소함에 따라 박테리아의 흡착정도와 Cu의 추출속도는 분명하게 선형적으로 증가했다. 다른 종류의 기질에 비해 재생로 분진에서 침출속도가 빠른 것은 주로 분진입자의 부서지기 쉬운 성질 때문으로 추정된다.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제3권1호
• /
• pp.43-53
• /
• 1999

A real $m{\times}n$ matrix A is called an L-matrix if every matrix in its qualitative class has linearly independent rows. Since the number of the sign pattern matrices of the given size is finite, we can list all patterns lexicographically. In [2], a necessary and sufficient condition for a matrix to be an L-matrix was given. We presented an algorithm which decides whether the given matrix is an L-matrix or not. In this paper, we develope an algorithm and C-program which will determine whether a given matrix is an L-matrix or not, or an SNS-matrix or not. In addition, we have extended our algorithm to be able to classify sign-pattern matrices, and to find barely L-matrices from a given matrix and to list all $m{\times}n$ L-matrices.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.914-917
• /
• 2002

Fabrication of micro carbon structures and patterns using laser-assisted chemical vapor deposition is studied. Argon ion laser and ethylene were used to grow micro carbon rod through pyrolytic decomposition of the reaction gas. The influence of reaction gas pressure and incident laser power on the diameter and growth rate of the micro carbon rod was experimentally investigated. The diameter of micro carbon rods increases linearly with respect to the laser power but is almost independent of the reaction gas pressure. Growth rate of the rod changes little with gas pressure when the laser power remains below 1W. When the carbon rod was grown at near threshold laser power, a very smooth surface is obtained on the rod. By continuously moving the focusing lens in the direction of growth, a micro carbon rod with a diameter of 28 ${\mu}{\textrm}{m}$ and aspect ratio of 100 was fabricated.

• Korean Journal of Mathematics
• /
• 제15권2호
• /
• pp.101-114
• /
• 2007

For an $m$ by $n$ nonnegative real matrix A, the maximal column rank of A is the maximal number of the columns of A which are linearly independent. In this paper, we analyze relationships between ranks and maximal column ranks of matrices over nonnegative reals. We also characterize the linear operators which preserve the maximal column rank of matrices over nonnegative reals.

• 한국안전학회지
• /
• 제21권3호
• /
• pp.122-126
• /
• 2006

This study investigated effect of arm posture, wrist motion repetition and external load on perceived discomfort through an experiment. Eleven female college students participated in the experiment, where shoulder, elbow and wrist motion, wrist motion repetition, and external load were used as independent variables. The results showed that only external load had a significant effect on perceived discomfort. The perceived discomfort linearly increased with external load. Based on the results of this and the previous study for males, it was concluded that effect of external load on perceived discomfort was larger than that of other posture and motion repetition related variables. This implies that effect of external load is the most important factor considered in the first place when assessing postural load.

• Structural Engineering and Mechanics
• /
• 제64권6권
• /
• pp.731-736
• /
• 2017

Friction Pendulum isolators are tools developed in the past few decades. The simplest form of these isolators, are FPS whose main disadvantages are having a constant frequency independent of the frequency of the structure. For this reason, researchers have invented VFPI isolator whose frequency is variable and depends on displacement. Another friction pendulum isolator is DCFP isolator which is a combination of two FPS isolators. In this article, first by changing the geometry of DCFP isolator plates from spherical to elliptical, the motion and frequency equations of DVFPI isolators are defined, and then the seismic behavior of DVFPI isolators are analyzed in various geometric and plate friction settings using motion equations, and confirmed using ABAQUS software. The most important results of this study are that the hysteresis behavior of DVFPI isolators are severely nonlinear, its curve follows two distinct curvatures, and that the restoring force is faced with softening mechanism that limits the seismic force transmitted to the structure, whereas the restoring force in DCFP isolators increases linearly with increasing displacement.

• 한국연소학회지
• /
• 제1권1호
• /
• pp.41-49
• /
• 1996

Effects of ambient geometry on the liftoff characteristics are experimentally studied for nonpremixed turbulent jet flames. To clarify the inconsistency of the nozzle diameter effect on the liftoff height, the ambiences of finite and infinite domains are studied. For nonpremixed turbulent jet issuing from a straight nozzle to infinite domain, flame liftoff height increases linearly with nozzle exit mean velocity and is independent of nozzle diameter. With the circular plate installed on the upstream of nozzle exit, flame liftoff height is lower with plate at jet exit than without, but flame liftoff characteristics are similar to the case of infinite domain. For the confined jet having axisymmetric wall boundary, the ratio of the liftoff height and nozzle diameter is proportional to the nozzle exit mean velocity demonstrating the effect of the nozzle diameter on the liftoff height. The liftoff height increases with decreasing outer axisymmetric wall diameter. At blowout conditions, the blowout velocity decreases with decreasing outer axisymmetric wall diameter and liftoff heights at blowout are approximately 50 times of nozzle diameter.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 하계종합학술대회논문집
• /
• pp.23-25
• /
• 1998

Many of the currently used PN code acquisition algorithms detect the phase of the incoming PN signal on the basis of ML estimation principle and utilize statistics grounded in taking inner products. By showing that any set of 2n-1 PN sequences arising in SSRG or MSRG (those typically used in IS'95 implementations) configuration constitutes a linearly independent set and that the number of candidate PN sequences has to equal the dimension of the span of the candidate PN sequences, we prove that the lowerbounding computational complexity involved in any PN code acquistion, utilizing (only) inner product computations at each stage of acquisition, corresponds precisely to those, such as double dwell acquistion circuitries, currently used.

• 대한화학회지
• /
• 제9권1호
• /
• pp.8-15
• /
• 1965

一般式中의 potential energy 變數로서 ${\sigma}$ Y를 使用할 수 있음을 밝혔고 또 關係式의 反應機構上의 意義를 論하였다. Benzyl chlorides의 solvolysis反應 data를 適用함으서 物質常數 ${\alpha}'$는 2個의 뚜렷한 系列을 形成하며 置換基常數 ${\sigma}$와는 各系列마다 別途로 直線關係를 가지며 이로서 $S_N1$으로부터 $S_N2$로의 反應機構의 變化를 알 수가 있었다.