• 충청수학회지
• /
• 제23권3호
• /
• pp.523-534
• /
• 2010

In this paper, we consider the weighted Bloch spaces ${\mathcal{B}}_q$(q > 0) on the open unit ball in ${\mathbb{C}}^n$. We prove a certain integral representation theorem that is used to determine the degree of growth of the functions in the space ${\mathcal{B}}_q$ for q > 0. This means that for each q > 0, the Banach dual of $L_a^1$ is ${\mathcal{B}}_q$ and the Banach dual of ${\mathcal{B}}_{q,0}$ is $L_a^1$ for each $q{\geq}1$.

• 한국항행학회논문지
• /
• 제22권3호
• /
• pp.205-212
• /
• 2018

자연발화의 문제는 심각한 경제적 손해뿐만 아니라 화재 시 발생하는 유해가스로 인해 환경오염을 발생시키는 대표적인 발전소 피해이다. 저탄장 자연발화 예방 및 조치하기 위해 드론을 이용하는 방법이 제시되었으나 외부의 측풍과 외란으로 인한 2차 사고의 발생위험이 존재하는 상황이다. 자연발화의 원인과 영향 인자는 매우 복잡하기 때문에 사전에 예방하기가 쉽지 않으며 일단 발생하면 소화하기도 어렵다. 따라서 저탄장 내부에서 직접적으로 온도 및 상태를 측정하고 자연발화 지점에 직접적으로 냉각 가스를 분출하여 소화하는 장치가 필요하다. 본 연구는 저탄장의 자연발화를 예방하기 위한 냉각볼 장치의 내부 압력과 외부 압력에 대하여 구조해석을 실시하고 구조적 안전성에 대하여 연구한다.

• Journal of Biosystems Engineering
• /
• 제31권3호
• /
• pp.146-152
• /
• 2006

Most upland in Korea have irregular field shapes. Boom sprayers working alone winding row will show considerable differences of spraying amount per unit area between left and right booms. If flow rates of both booms are equal. This phenomenon becomes significant as steering radius of sprayer decreases. This study was performed to seek a method which reduce the difference of the spray amount between left, right and center booms while spraying along curvy rows. A flow rate control method for keeping application rate of each boom section constant was proposed and experimentally proved using a boom sprayer attached to a cultivating tractor. The flow rate control device was composed of 3 ball valves and a rotary angle sensor. The rotary angle sensor showed a symmetric voltage output with respect to steering radius. The spray overlapping was happened in a boom nearby the steering center when steering radius of the sprayer was less than 5.2 m. Flow rates for left, right and center booms were regulated using ball valves based on the steering radius and spraying areas ration of right/left boom. The Maximum spraying area ratio ($S_{LR}$) of left to right boom section was 1:3.6 at the steering radius of 5.2 m. However, The Maximum achieved right and left spraying flow ratio was 1:2.7.

• Journal of Welding and Joining
• /
• 제31권5호
• /
• pp.54-58
• /
• 2013

Joint properties of vehicle ECU (Electric Control Unit) module which was manufactured by using Sn-Cu-Cr-Ca alloy were investigated. A new solder which has a middle melting temperature about $231^{\circ}C$ was fabricated as the type of 300um solder ball and paste type. The prototype modules were made by reflow process and measured spreadability, wettability shear strength and estimated interface reaction. The spreadability of the alloy was about 84% from the measurement of contact angle of the solder ball and the wetting force was measured 2mN. The average shear strength of the module which was manufactured by using the solder paste, was 1.9 $kg/mm^2$. Also, the thickness of IMC(intermetallic compound) was evaluated with various aging temperature and time in order to understand Cr effect on Sn-0.7Cu solder. $Cu_6Sn_5$ IMC was formed between Cu pad and the solder alloy and the average thickness of the $Cu_6Sn_5$ IMC was measured about 4um and it was about 50% of thickness of $Cu_6Sn_5$ IMC in Sn-0.7Cu. It is expected to have a positive effect on reliability of the solder joint.

• Journal of Biosystems Engineering
• /
• 제29권2호
• /
• pp.151-158
• /
• 2004

This research was conducted to study the offensive odor adhesion efficiency of filter bed materials using the experimental column that was designed and constructed in this work. The offensive odor adhesion experiment was conducted using mixture of high physical adhesion efficiency material, and the fixity of deodorization microorganism of selected filter bed material was tested using ammonia exclude microorganism A4-2 and sulfur oxidation microorganism S5-5.2 those were cultured at the Agricultural Chemical Department of Chungnam National University, and deodorization efficiency of selected filter bed material mixture was tested. Followings are summary of these tests results. 1) Amount of elimination of the offensive odor gas ammonia and hydrogen sulfide per unit volume were 0.054 and 0.016 $\ell$/㎤ in rice hull, 0.01 and 0.004 $\ell$/㎤ in rice straw, 0.158 and 0.01 $\ell$/㎤ in coconut, 0.014 and 0.02 $\ell$/㎤ in perlite, 0.004 and 0.003 $\ell$/㎤ in high road ball, and 0.112 and 0.015 $\ell$/㎤ chaff of pine, respectively. 2) Amount of elimination of offensive odor gas of ammonia and hydrogen sulfide per unit vloume were 0.079 and 0.016 $\ell$/㎤ in mixture 1, 0.045 and 0.014 $\ell$/㎤ in mixture 2, 0.123 and 0.017 $\ell$/㎤ in mixture 3, 0.055 and 0.016 $\ell$/㎤ in mixture 4, 0.031 and 0.015 $\ell$/㎤ in mixture 5, and 0.111 and 0.020 $\ell$/㎤ in mixture 6, respectively. 3) The offensive odor elimination microoraganism inoculated to the mixture of chaff of pine (70%) and pert (30%) showed the elimination efficiency of 99.06% and 96.61% against the ammonia and hydrongen sulfide, respectively, during 24 hours period.

• 한국건축시공학회지
• /
• 제9권6호
• /
• pp.105-111
• /
• 2009

건설기계는 건설사업의 성공적인 수행의 중요한 요인이며, 건설기계에 소요되는 비용이 건설공사비에서 차지하는 비중은 점차 증가하고 있다. 우리나라는 표준품셈에 제시된 건설기계 시공능력 산정식을 이용하여 건설기계의 시간당 작업량을 계산하고 있다. 건설기계 성능은 개선되고 있으나 시공능력 산정식에서 활용되고 있는 요소들은 이를 반영하지 못하고 있는 실정이며 극히 부분적으로만 재 개정되었다. 본 연구에서는 건설기계 시공능력 산정식 요소 중 사이클타임에 대해서 조사하였다. 이를 위해 먼저 관련 선행연구를 분석하였고, 건설공사에 주로 사용되는 건설기계인 굴삭기와 로우더의 사이클타임을 실사하였다. 수집된 자료와 현행 표준품셈의 시공능력 산정식에 적용되는 수치를 바탕으로 시뮬레이션 프로그램인 크리스탈볼을 활용하여 건설기계의 시공능력을 산정하였다.

• Kyungpook Mathematical Journal
• /
• 제56권3호
• /
• pp.781-791
• /
• 2016

Let $d_*(1,w)^2 ={\mathbb{R}}^2$ with the octagonal norm of weight w. It is the two dimensional real predual of Lorentz sequence space. In this paper we classify the smooth points of the unit ball of the space of symmetric bilinear forms on $d_*(1,w)^2$. We also show that the unit sphere of the space of symmetric bilinear forms on $d_*(1,w)^2$ is the disjoint union of the sets of smooth points, extreme points and the set A as follows: $$S_{{\mathcal{L}}_s(^2d_*(1,w)^2)}=smB_{{\mathcal{L}}_s(^2d_*(1,w)^2)}{\bigcup}extB_{{\mathcal{L}}_s(^2d_*(1,w)^2)}{\bigcup}A$$, where the set A consists of $ax_1x_2+by_1y_2+c(x_1y_2+x_2y_1)$ with (a = b = 0, $c={\pm}{\frac{1}{1+w^2}}$), ($a{\neq}b$, $ab{\geq}0$, c = 0), (a = b, 0 < ac, 0 < ${\mid}c{\mid}$ < ${\mid}a{\mid}$), ($a{\neq}{\mid}c{\mid}$, a = -b, 0 < ac, 0 < ${\mid}c{\mid}$), ($a={\frac{1-w}{1+w}}$, b = 0, $c={\frac{1}{1+w}}$), ($a={\frac{1+w+w(w^2-3)c}{1+w^2}}$, $b={\frac{w-1+(1-3w^2)c}{w(1+w^2)}}$, ${\frac{1}{2+2w}}$ < c < ${\frac{1}{(1+w)^2(1-w)}}$, $c{\neq}{\frac{1}{1+2w-w^2}}$), ($a={\frac{1+w(1+w)c}{1+w}}$, $b={\frac{-1+(1+w)c}{w(1+w)}}$, 0 < c < $\frac{1}{2+2w}$) or ($a={\frac{1=w(1+w)c}{1+w}}$, $b={\frac{1-(1+w)c}{1+w}}$, $\frac{1}{1+w}$ < c < $\frac{1}{(1+w)^2(1-w)}$).

• Applied Microscopy
• /
• 제43권3호
• /
• pp.117-121
• /
• 2013

Mitochondrion is an important intracellular organelle controlling energy production essential for cell survival. In addition, it is closely related to cellular apoptosis and necrosis. Linear, branched, circular, and ball-shaped mitochondria have been reported. Recent research suggests that mitochondrial morphology may reflect functional status of the cell. In this study, we investigated the density and ratio of the each morphological categories of mitochondria in a few normal cultured cells; astrocyte, HeLa and COS7 cells, of which metabolic activities are different, with high voltage electron microscopy. The absolute number and relative number per unit area of mitochondria was largest in astrocyte. But, the proportion of different mitochondrial shape was similar among cells. These results shows the numerical profiles but not morphological profiles of mitochondria are related to the metabolic activity of each cell line.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권4호
• /
• pp.139-143
• /
• 2005

For application of carbon nano-tube (CNT) as a counter electrode materials of dye-sensitized solar cell (DSSC), the electrochemical behavior of CNT electrode was studied, employing cyclic-voltammetry (C-V) and impedance spectroscopy. Fabrication of CNT-paste and formation of CNT-counter electrode for characteristic measurement have been carried out using ball-milling and doctor blade process, respectively. Unit cell for measurements was assembled using Pt electrode, CNT electrode, and iodine-embedded electrolyte. Field emission-scanning electron microscopy (FE-SEM) was used for structural investigation of CNT powder and electrode. Sheet resistance of electrode was measured with 4-point probe method. Electrochemical properties of electrode, C-V and impedance spectrum, were studied, employing potentiogalvanostat (EG&G 273A) and lock in amplifier (EG&G 5210). As a results, the sheet resistance of CNT electrode is almost similar to that of F-doped SnO2 (FTO) coated glass substrate as approximately 10 ohm/sq. From C-V and impedance spectroscopy measurements, it was found that CNT electrode has high reaction rate and low interface reaction resistance between CNT surface and electrolyte. These results provides that CNT electrode were superior to that of conventional Pt electrode. Particularly, the reaction rate in the CNT electrode is about thrice high than Pt electrode. Therefore. CNT electrode is to be good candidate material for counter electrode in DSSC.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권6호
• /
• pp.572-577
• /
• 1996

Alternating current and direct current of pure, ball milled, and $Al_{2}$O$_{3}$ added ZnO were investigated by means of complex impedance measurement and voltage-current source measurement unit. The electrical conductivity of A1$_{2}$O$_{3}$ added ZnO samples increases when the content of A1$_{2}$O$_{3}$ is used within 1 at% and decreases when it's used more than that. The increase and decrease of electrical conductivity seem to be the donor effect of $Al_{2}$O$_{3}$ and the increase of the number of ZnO grains, respectively. Impedance spectrum seems to be one semircicle. The size of semicircle increase with increasing the A1$_{2}$O$_{3}$ contents. The calculated dielectric constant(at 50.deg. C) were about 70-140 at the peak of the semicircle. The semicircles seem not to be the resistance of ZnO grain as compared to that of 10 for pure ZnO.