• Journal of Ship and Ocean Technology
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• 제11권2호
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• pp.10-25
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• 2007

With the sharp increase of the oil price, the issue of the energy saving requires even higher propulsive efficiency of the propellers. Traditionally the propellers have been designed with the criteria such as that of Lerbs optimum based on the lifting line theory and the empirical formulae of Lerbs and van Manen giving relations of the wake pitch with the wake non-uniformity. With the aid of the high speed computer, it is now possible to apply the time-consuming iterative approaches for the solution of the lifting surface problems. In this paper we formulate the variational problem to optimize the efficiency of the propeller operating in the given ship wake using the lifting surface method. The variational formulation relating the spanwise circulation distribution with the propulsive efficiency to be maximized is however non-linear in circulation distribution functions, thus the iterative method is applied to the quasi-linearized equations. The blade shape design also requires the iterative procedures, because the shape of the blade which is represented by the lifting surface is unknown a priori. The numerical code was validated with the DTNSRDC propeller 4119 which is well-known to be optimum in uniform inflow condition. In addition existing (well-designed) commercial propellers were selected and compared with the results of the open water tests and the self-propulsion tests.

• Archives of Plastic Surgery
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• 제34권6호
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• pp.807-812
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• 2007

Purpose: The presence of epicanthal fold and the absence of supratarsal fold are characteristics of Korean eyelids. There has been many surgical procedures to eliminate medial epicanthal fold but those procedures focus on the lengthening of horizontal palpebral fissure and the shortening of intercanthal distance so that the shape of eye had tendency to be sharp. The authors suggest that the supermedial shifting of epicanthal fold enhance the aesthetic result. Methods: From Sep 2006 to May 2007, total 17 women(mean age 22) with Type III epicanthal fold underwent epicanthoplasty using author's modified Uchida method. The design for epicanthoplasty was drawn superolaterally along epicanthal fold and split V-W plasty was done to shift the epicanthal fold superomedially. Also non-incisional double-eyelid operation was underwent. Results: The epicanthal fold was shifted in superomedially, intercanthal distance was shortened and double-eyelid was achieved. The patients were satisfied with the result and no major complication was noted. Conclusion: This method can be effective in correcting the epicanthal fold of Korean eyelid by shifting the epicanthal fold superomedially to make the shape of eye aesthetically without noticeable scar.

• 한국분말재료학회지
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• 제18권4호
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• pp.378-384
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• 2011

In this research, the indium dissolution properties of the waste LCD panel powders were investigated as a function of milling time fabricated by high-energy ball milling (HEBM) process. The particle morphology of waste LCD panel powders changed from sharp and irregular shape of initial cullet to spherical shape with an increase in milling time. The particle size quickly decreased to 15 ${\mu}m$ until the first minute, then decreased gradually about 6 ${\mu}m$ with presence of agglomerated particles after 5 minutes, which increased gradually reaching a uniform size of 13 ${\mu}m$ consist of agglomerated particles after 30 minutes. The glass recovery, after dissolution, was over 99% at initial cullet, which decreased to 90.1 and 78.6% with increasing milling time of 1 and 30 minute respectively, due to a loss in remaining powder of the surface ball and jar, as well as the filter paper. The dissolution amount of indium out of the initial cullet was 208 ppm before milling, turning into 223 ppm for the mechanically milled powder after 1 minute, and nearly 146~125 ppm with further increase in milling time because of the reaction surface decrease of powders due to agglomeration. With this process, maximum dissolving indium amount (223 ppm) could be achieved at a particle size of 15 ${\mu}m$ with 1 minute of milling.

• Applied Microscopy
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• 제35권4호
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• pp.42-54
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• 2005

본 연구는 무당개구리과 (Discoglossidae)의 무당개구리(Bombina orientalis) 정자의 형태적 특징을 광학현미경과 주사 및 투과 전자현미경으로 관찰하였다. 정자두부는 전 후방의 끝이 뾰족하고 다소 유연성을 갖는 초생달 혹은 버들 잎 모양의 특이한 구조를 취하고 있었다. 핵은 전 후방이 가늘고, 중앙 부분은 굵은 원뿔형이었다. 염색질은 완전하게 농축되어 있지 않고, 마치 널빤지를 겹쳐 놓은 듯한 지붕모양과 같은 형태로 불규칙하게 배열되어져 있었다. 핵 내에는 불규칙한 형태의 nuclear lacunae들이 흩어져 있었다. 정자경부와 중편부는 발달 되어 있지 않았다. 편모는 9+2 구조의 axoneme, axial rod 그리고 undulating membrane을 가지고 있었다. 미토콘드리아들은 핵의 상단부를 둘러싸고 있는 protoplasmic bead내에만 국한되어 존재하고 있었다. 특히, 본 연구에서 핵의 전방부에서 중앙 부위로 주행하는 nuclear rod는 섬유성 다발로 구성되었으며, 마치 사람의 속눈썹 모양과 같은 형태를 취하며, 핵의 2/3까지 뻗쳐져 있었다.

• 한국결정성장학회지
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• 제4권2호
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• pp.157-168
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• 1994

APCVD에 의한 $SnO_2(:F)$ 박막 형성시 HF와 $H_2O$량의 변화에 따른 증착 조건이 전기적, 광학적 특성 그리고 textured $SnO_2(:F)$ 박막의 표면형상에 미치는 영향을 관찰하였다. HF의 bubbling량이 0.9 slm 이상일 경우에는 전자농도(electron concentration)가 $3{\Times}10^{20}/cm^3$에 도달 하였으며, 비저항값은 $7{\Times}10^4~9{\Times}10^4{Omega}cm$ 범위이었고, mobility 값은 $18~25 cm^{-2}/V.sec$이었다. 결정 grain의 형태는$H_2O$를 첨가시키지 않으며 증착시킨 경우 끝이 뾰족한 예각을 가진 pyramid 형태였으며, $H_2O$를 첨가시키며 증착시킨 경우에는 끝이 둥근 hemispherical 형이었다.

• 융합신호처리학회논문지
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• 제1권1호
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• pp.23-31
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• 2000

본 논문에서는 물체의 경계나 형태 추출을 위하여 레벨 세트 이론을 바탕으로 한 새로운 곡선 전개방법을 제안한다. 특히 전처리 과정에서 잡음의 효과적 처리를 위하여 기존의 필터 방식들이 가지는 단점인 경계 부분의 bluning 현상을 줄이고 정확한 에지 위치를 보존할 수 있는 비등방성 확산 필터(anisotropic diffusion filter)를 사용한다. 기존의 레벨 세트 방식이 수축이나 팽창 중 단지 한가지의 방식만 적용되어지는 반면, 제안한 방법은 물체의 경계 추출시 팽창과 수축이 통시에 가능하므로 특히 초기 곡선이 여러 물체에 걸쳐져 있는 경우에도 정확한 형태 추출이 가능하였다. 아울러 초기 곡선의 설정이 위치나 형태에 거의 제한을 받지 않기 때문에 추출을 원하는 영역이 아주 조금만 포함되어 있어도 정화한 형태 추출이 가능하였다.

• 자원환경지질
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• 제26권4호
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• pp.455-464
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• 1993

Some nodules occur in the Milyang pyrophyllite deposit which are hydrothermal alteration products by Late Cretaceous andesitic tuff. These nodules are divided into two types on the basis of mineral assemblages; diaspore and pyrophyllite nodules. The diaspore nodules consist mainly of diaspore, kaolinite, pyrophyllite and pyrite with a small amounts of wavellite and tourmaline. They are light purplish grey in color, ellipsoid in shape and range 1 cm to 15 cm in size. A small or large diffuse band exists in some nodules. The platy coarse-grained diaspore is intergrown with the fine-aggregated kaolinite in the central part of the nodule. It appears that the grain size become fine from center to margin. The pyrophyllite nodules, which have the same shape with diaspore nodules, consist dominantly of pyrophyllite accompanied by small amounts of quartz, kaolinite, svanbergite, wavellite, tourmaline and apatite. Chemical compositions of alteration zones and nodules show that the wall rock alteration involved mainly the removal of large quantities of silica and alkalies and small quantities of Ca, Mg and Fe. The sharp increase in the Al content of the nodules is the result of residual concentration of alumina by the leaching of the mobile components. The pyrophyllite nodules were formed in the fluid saturated with quartz as ${\mu}_{HK_{-1}}$ and ${\mu}_{H_{2}O}$ increase. Under this condition, the pyrophyllite-kaolinite-quartz assemblage was stable. Diaspores formed from pyrophyllites in the fluid undersaturated with quartz as ${\mu}_{H_{2}O}$ increases (decreasing temperature). Under this condition, diaspore-pyrophyllite-kaolinite assemblage become stable. The formation temperature of the nodules on the basis of mineral assemblage is estimated as $275{\sim}340^{\circ}C$.

• The Korean Journal of Physiology and Pharmacology
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• 제7권1호
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• pp.47-52
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• 2003

The prostate gland contains numerous neuroendocrine cells that are believed to influence the function of the prostate gland. Our recent study demonstrated the expression of both ${\alpha}1$- and ${\alpha}2$-ARs, signaling the release of stored $Ca^{2+}$ and the inhibition of N-type $Ca^{2+}$ channels, respectively, in rat prostate neuroendocrine cells (RPNECs). In this study, the effects of NA on the resting membrane potential (RMP) of RPNECs were investigated using a whole-cell patch clamp method. Fresh RPNECs were dissociated from the ventral lobe of rat prostate and identified from its characteristic shape; round or oval shape with dark cytoplasm. Under zero-current clamp conditions with KCl pipette solution, the resting membrane potential (RMP) of RPNECs was between -35 mV and -85 mV. In those RPNECs with relatively hyperpolarized RMP (＜-60 mV), the application of noradrenaline (NA, $1{\mu}M$) depolarized the membrane to around -40 mV. In contrast, the RPNECs with relatively depolarized RMP (＞-45 mV) showed a transient hyperpolarization and subsequent fluctuation at around -40 mV on application of NA. Under voltage clamp conditions (holding voltage, -40 mV) with CsCl pipette solution, NA evoked a slight inward current (＜-20 pA). NA induced a sharp increase of cytosolic $Ca^{2+}$ concentration ($[Ca^{2+}]_c$), measured by the fura-2 fluorescence, and the voltage clamp study showed the presence of charybdotoxin-sensitive $Ca^{2+}$-activated $K^+$ currents. In summary, adrenergic stimulation induced either depolarization or hyperpolarization of RPNECs, depending on the initial level of RMP. The inward current evoked by NA and the $Ca^{2+}$-activated $K^+$ current might partly explain the depolarization and hyperpolarization, respectively.

• 대한기계학회논문집
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• 제12권6호
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• pp.1399-1406
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• 1988

본 연구에서는 수로의 폭이 작고(W=74mm) H$_{w}$/H$_{g}$가 5.0~16.7의 범 위인 경우에 레이져 유속계를 이용하여 주어진 유동조건, 예컨대, 유입유속, 입구게이 크(gate)의 높이, 수위, 배플의 유. 무및 높이, 그리고 배플의 위치등에 따라서 액체 속도의 분포가 어떻게 변화하는가를 정성적으로 관찰해 보고자 하는데 주안점을 두었 다. 본 실험 결과는 차후에 계속될 후래시 증발현상에 관한 실험및 해석적 접근에 관한 기초 자료로서 활용하는데에도 그 목적이 있다.다.

• 한국군사과학기술학회지
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• 제17권4호
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• pp.463-470
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• 2014

Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.