• Applied Microscopy
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• v.35 no.4
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• pp.74-83
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• 2005

The ontogeny of pollen wall in Panax ginseng was studied with transmission and scanning electron microscopy from early tetrad stage until pollen maturity. Initial indication of exine development is undulation of plasma membrane for the preparation of bacular mound. The first recognizable structure of the pollen wall is the cellulosic primexine which is formed outside of the plasma membrane while microspore tetrads are still surrounded by callose wall. As development proceeds, foot-layer and baculum differentiation, callose dissolution and exine formation were progressed. During this process, sporopollenin is deposited into the exine, and then endexine development was followed. The intine, innermost pollen wall layer, is developing form hypertrophic Golgi vesicles. The thickness of exine is very even on all along the pollen wall, but intine thickness of apertural region is thicker than that of nonapertural region. Mature pollen of ginseng is $20{\mu}m$ in size, tricolpate and shows fine reticulate sculpturing.

• Progress in Medical Physics
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• v.10 no.3
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• pp.115-123
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• 1999

The two dimensional echocardiography is widely used to evaluate regional wall motion abnormality, because of its abilities to depict left ventricular wall motion. A number of researches have been processed for evaluation and quantitative analysis of left ventricular wall motion functions. In this paper, we proposed an algorithm which detects automatically and analyze quantitatively endocardial wall motion during systole. The echocardiograms were obtained in the short-axis views in normal subjects. Automated edge detection and endocardial contour tracking algorithm was applied to each frames, quantitative analysis based on segmentation was performed, pre-defined color overlays superimposed on the gray scale images, and the images was animated. The proposed algorithm provided automated, quantitative diagnosis of regional wall motion abnormality.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.481-486
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• 2008

The different degrees of blackening were observed at the inner surface of borosilicate, soda-lime, and aluminosilicate glass tubes having different sodium (Na) contents. The sodium contents ($Na_2O$) within the borosilicate, soda-lime, and aluminosilicate glass tubes were found to be 4%, 14%, and 0.06%, respectively. The degree of blackening was shown to increase as the sodium content within the glass of the fluorescent lamp containing Ne+Ar+Hg gas mixture. Higher degree of blackening was observed from the inner surface of the glass tube coated with $Y_2O_3$. The blackening was found to be originated from the amalgam of $NaHg_2$ generated by the chemical reaction between the mercury ions within the discharge gas and sodium within the glass tube during operation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.107-113
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• 2005

A calorimeter of 2-ton thrust level rocket engine chamber has been developed to measure the wall heat flux. The liner of the chamber is made of copper-chromium alloy to maximize the heat transfer performance and structural strength. 1-D design code based on empirical correlations has been used for the prediction of the global thermal characteristics while 3-D CFD has been applied for the verification of local cooling performance. The predicted average wall heat flux at the throat is 43 $MW/m^{2}$ for the combustion chamber pressure of 53 bar. The chamber structure is confirmed to be safe at the pressure of 150 bar through 2-D stress analysis and measurement of the strain of the test species. Finally, the test of pressurizing the calorimeter chamber has been performed with water at the pressure of 150 bar in room temperature environment. No thermal damage has been detected after the hot-fire test in the test nozzle of same cooling performance with the developed calorimeter though the measured throat heat flux is higher than the design value by 10%.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.287-294
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• 2008

Molecularly imprinted polymer (MIPs) membranes were prepared by UV polymerization to separate racemates with opposite physiological activity, and then its separation selectivity of racemates was carried out. Likewise, their properties were examined. Polycarbonate (PC) membrane was polymerized as small spot form in pore inner wall, but anodisc (AD) membrane was polymerized as film form with thickness 500~700 nm onto the membrane surface. Also the study on the separation selectivity of prepared MIPs membranes was carried out in L-Tryptophane (Trp) racemate solution. The results showed that AD MIPs membrane polymerized as a film form, which was achieved by solution polymerizaion consisting of over 90% cross-linking agent (ethylene glycol dimethacrylate; EGDMA) and under 30% dispersing agent (methanol; MeOH), had predominant 3.5 selectivity.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.515-524
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• 1998

The purposes of this study were to observe the cavity wall morphology and to evaluate the degree of cavity cleanliness when root-end retrograde cavity preparation was done with ultrasonic diamond instruments. To observe the morphology of retrocavity and to evaluate the degree of cavity cleanliness. root-end resections were done on 20 palatal roots of extracted maxillary first molars after canal filling with gutta-percha. Retrocavities were prepared using either ultrasonic diamond instruments or stainless steel ones of medium power setting of level 6 ($Miniendo^{TM}$, EIE, CA, U.S.A.). Morphology of the cavity. degrees of the remaining canal debris and smear layer were evaluated under the scanning electron microscope. The results were as follows: Cavities prepared with ultrasonic diamond instruments showed scratched appearance of wall, while ultrasonic stainless steel preparation showed hatcheted appearance. Ultrasonic diamond instruments induced more smear layer than stainless steel ones did (p<0.01) in the cavity. However, there was no significant difference in canal debris (p>0.05).

• Korean Journal of Materials Research
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• v.7 no.11
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• pp.1012-1017
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• 1997

Mg-Zn-Ca합금의 잉곳트는 BN을 내벽에 바른 4x$10^{-5}$Torr의 진공의 석영관내에서 제조하였다. Mg-Zn합금계의 입자미세화를 위하여 0.5-5wt.%조성범위의 Ca를 첨가하였다. 제조된 합금을 용체화처리한 후 결정립크기와 경도를 측정하였다. Mg-6wt.%Zn합금의 입자미세화효과는 Ca가 1.5wt%첨가 될 때 최적의 조건이었다. Mg-6wt.% Zn과 Mg-6wt.% Zn-2wt.% Ca및 Mg-6wt.% Zn-1.5wt.% Si합금을 시효처리하여 시효거동을 조사하였다. 입자미세화에 의한 경도증가효과는 Mg-Zn-Ca합금계에서 크게 나타났으며 시효에 의한 경도증가효과는 Mg-Zn-Si합금계에서 크게 나타났다. Mg-6wt.%Zn합금의 부식전류밀도는 0.5wt.% Ca의 조성에서 감소되었다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.10
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• pp.1294-1304
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• 1995

In this paper, a method has been proposed for the fully automatic detection of left ventricular endocardial boundary in B-mode short axis echocardiography without manual intervention by human operator. The proposed method makes use of the weighted model that approximates to endocardium and incomplete edge information for echocardiography. Therefore, this method is more effective than boundary detection by only edge information. The implementation of this method is as follows. First, the proposed algorithms are used in order to detect the approximate boundary, then a weighted model with the approximate boundary is constructed. Finally, the cavity center of the left ventricle performing the Hough transform with the weighted model and edge image can be found automatically, and then the endocardial boundary using detected center, original image, weighted model, and edge image can be detected. validations of this method with experimental results on echo image of dog's heart and clinical echocardiography is verified.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.425.2-425.2
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• 2016

토카막(TOKAMAK) 장치의 진공용기 및 용기내벽은 플라즈마(Plasma)에 의한 고열과 높은 에너지의 이온 입자들에 항상 노출되어 있는 환경이다. 토카막의 일종인 KSTAR장치의 진공용기는 스테인레스강(STS316)계열의 재질로 이루어져 있고, 플라즈마와 면하는 용기 벽면은 플라즈마에 대해 견딜 수 있도록 그라파이트 타일(graphite tile)로 구성되어 있다. 고에너지의 이온 입자들과 열플럭스(Heatflux)는 용기벽면과 용기를 침식시키고, 또한 이렇게 생겨난 분진(dust)들은 진공용기 내 여기저기를 떠다니게 되고, 플라즈마에 대해서 불순물로서 작용하게 된다. 본 연구에서는 감마분석법으로 플라즈마에 의해 진공용기 내에 집적된 분진들의 구성 성분을 분석하여 주요 출처를 규명할 수 있는 방법을 제시하고, KSTAR 플라즈마의 불순물 제어에 유용하게 활용 할 수 있는 데이터를 제공하여 향후 KSTAR의 고성능 플라즈마 기술개발에 일조할 수 있도록 하고자 한다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.47.2-47.2
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• 2009

Ti 및 S를 함유하는 강종의 연속주조시 노즐막힘 현상이 자주 발생한다. 이러한 강종의 연주기술과 생산성을 향상 시키기 위해서는 노즐막힘 발생을 방지하기 위한 새로운 기술의 개발이 필요하다. 노즐막힘은 노즐내벽에 개재물의 부착으로 인해 발생되는 것으로 용강의 물성 혹은 내화물 재질의 개선을 통하여 방지하거나 저감할 수 있다. 본 연구에서는 노즐내 용강에 Mg 증기를 취입하였을 때의 내화물과 용강 계면에서의 반응 및 현상에 대하여 조사하고 내화물/용강계면에서의 생성물 분석과 용강중 S와 Ti의 농도에 따른 노즐 내화물과의 접촉각을 측정하였다. Mg증기는 MgO-Al 혼합물을 가열함으로 Al에 의한 Mg 의 환원반응에 의해 발생되며, 온도와 MgO와 Al 분말의 입도에 따른 Mg증기 발생거동에 대하여 고찰한다.