• 한국지구과학회지
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• 제28권1호
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• pp.54-63
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• 2007

경상남도 사천시의 백악기 육성퇴적층인 진주층에서는 다양한 종류(막대기형, 멍울형, 층형, 작은 기둥형)의 스트로마톨라이트(stromatolite)가 산출된다. 세계적 산출 경향과는 달리 막대기형 스트로마톨라이트가 대량으로 발견되었다. 이는 나뭇가지에 부착 서식하던 미세조류에 의하여 탄산염 광물이 침전하여 동심원 모앙의 엽층리를 형성하여 생성된 구조이다. EPMA를 이용하여 구성광물, 속성작용, 풍화과정의 진행을 확인했다 일반적인 스트로마톨라이트는 내지성 화석이지만 막대기형 스트로마톨라이트는 외지성 화석으로도 산출될 수 있다는 점에서 특이하다. 전형적인 스트로마톨라이트의 미세 엽층리는 막대기의 포위 부분에 있으며, 여기서 최소 두 종류의 사상체 남조세균(평균 $2.2{\mu}m$와 $7.8{\mu}m$ 녹조류(평균 $32.3{\mu}m$ 발견하였으며, 이 때 남조세균은 피막 건설자이고, 녹조류는 피막 보조자로 판단되었다. 일부 박테리아에서는 세포사를 발견할 수 있었다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.418-421
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• 2002

Fundamental study on quasi-monochromatic parallel radiography using a polycapillary plate and a plane-focus x-ray tube is described. The x-ray generator consists of a negative high-voltage power supply, a filament (hot cathode) power supply, and an x-ray tube. The negative high-voltage is applied to the cathode electrode, and the transmission type target (anode) is connected to the ground potential. The maximum voltage and current of the power supply were -100 kV (peak value) and 3.0 mA, respectively. In this experiment, the tube voltage was regulated from 20 to 25 kV, and the tube current was regulated by the filament temperature and ranged from 1.0 to 3.0 mA. The exposure time is controlled in order to obtain optimum film density, and the focal spot diameter was about 10 mm. The polycapillary plate is J5022-21 made by Hamamatsu Photonics Inc., and the outside and effective diameters are 87 and 77 mm, respectively. The thickness and the hole diameter of the polycapillary are 1.0 mm and 25 ${\mu}$m, respectively. The x-rays from the tube are formed into parallel beam by the polycapillary, and the radiogram is taken using an industrial x-ray film of Fuji IX 100 without using a screen. In the measurement of image resolution, we employed three brass spacers of 2, 30, and 60 mm in height. By the test chart, the resolution fell according to increases in the spacer height without using a polycapillary. In contrast, the resolution slightly fell with corresponding increases in the height by the polycapillary. In angiography, fine blood vessels of about 100 ${\mu}$m are clearly visible.

• 한국재료학회지
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• 제9권9호
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• pp.861-864
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• 1999

다중 음극 전자빔을 이용한 새로운 플라즈마 소스를 설계하고 제작하였다. 대면적의 플라즈마를 발생시키기 위해 다중 음극을 채택하였다. 다중 음극 전자빔 플라즈마 소스(multi-cathode electron beam plasma source, MCEBPS)를 이용하여 300mm 또는 그 이상의 직경을 가진 웨이퍼에 안정한 플라즈마를 생성시킬 수 있었다. 텅스텐 필라멘트를 음극으로 사용하였다. 직경 320mm의 넓이에서, plasma potential $V_p$와 floating potential $V_f$ 모두 균일하게 유지되었고 $V_p와 V_f$의 차이도 낮은 값으로 나타났다. 플라즈마 밀도는 약 $10^{10} cm^{-3}$ 정도로 측정되었고 반경걸에 따른 편차는 작게 나타났다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.550-551
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• 2013

Large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER plasmas. Negative hydrogen (deuterium) ion sources are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck- Institute for Plasma Physics, Garching) for ASDEX-U and W7-AS neutral beam injection (NBI) systems. In recent, the first NBI system (NBI-1) has been developed successfully for the KSTAR. The first and second long-pulse ion sources (LPIS-1 and LPIS-2) of NBI-1 system consist of a magnetic bucket plasma generator with multi-pole cusp fields, filament heating structure, and a set of tetrode accelerators with circular apertures. There is a development plan of large-area RF ion source at KAERI to extract the positive ions, which can be used for the second NBI (NBI-2) system of KSTAR, and to extract the negative ions for future fusion devices such as ITER and K-DEMO. The large-area RF ion source consists of a driver region, including a helical antenna (6-turn copper tube with an outer diameter of 6 mm) and a discharge chamber (ceramic and/or quartz tubes with an inner diameter of 200 mm, a height of 150 mm, and a thickness of 8 mm), and an expansion region (magnetic bucket of prototype LPIS in the KAERI). RF power can be transferred up to 10 kW with a fixed frequency of 2 MHz through a matching circuit (auto- and manual-matching apparatus). Argon gas is commonly injected to the initial ignition of RF plasma discharge, and then hydrogen gas instead of argon gas is finally injected for the RF plasma sustainment. The uniformities of plasma density and electron temperature at the lowest area of expansion region (a distance of 300 mm from the driver region) are measured by using two electrostatic probes in the directions of short- and long-dimension of expansion region.

• 분석과학
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• 제34권2호
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• pp.87-98
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• 2021

In this study, we developed the nanoparticle multi-generator by 3D printer fusion deposition modeling (FDM) method that can reliably generate and deliver nanoparticles at a constant concentration for inhalation risk assessment. A white ABS filament was used as the test material, and SMPS was used for concentration analysis such as particle size and particle distribution. In the case of particle size, the particle size was divided by 100 nm or less and 100 to 1,000 nm, and the number of particles concentration, mass concentration, median diameter of particles, geometric average particle diameter, etc were measured. The occurrence conditions were the extruder temperature, the extruding speed of the nozzle, and the air flow rate, and experiments were conducted according to the change of conditions including the manufacturer's standard conditions. In addition, the utility of inhalation risk assessment was reviewed through a stability maintenance experiment for 6 h. As a result of the experiment, the size of the nanoparticles increased as the discharger temperature increased, as the discharge speed of the nozzle increased, and as the air flow rate decreased. Also, a constant pattern was shown according to the conditions. Even when particles were generated for a long time (6 h), the concentration was kept constant without significant deviation. The distribution of the particles was approximately 80 % for particles of 60 nm to 260 nm, 1.7 % for 1 ㎛ or larger, 0.908 mg/㎥ for the mass concentration, 111 nm for MMAD and 2.10 for GSD. Most of the ABS particles were circular with a size of less than 10 nm, and these circular particles were aggregated to form a cluster of grape with a size of several tens to several hundred nm.

• 한국약용작물학회지
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• 제13권1호
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• pp.21-29
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• 2005

경남지역의 자생 둥굴레속 47개 수집종의 유연관계를 분석하기 위한 기초자료로서 수집종의 생장 몇 형태 관련 형질, 잎마름병 감염정도, 이들 형질간 상관관계를 분석하였던 바 그 결과는 다음과 같다. 1. 초장은 산둥굴레에서 가장 길었던 반면, 용둥굴레에서 가장 짧았다. 한편 줄기의 생장형태는 직립형을 포함한 3개군으로, 줄기색깔은 녹색을 포함한 3개군으로 분류하였다. 2. 염의 형태로는 타원형을 포함한 5개군으로, 엽병은 존재 유무로부터 2개군으로, 엽병의 색깔은 녹색을 포함한 3개군으로 분류되었으며, 그 중에 특이하게 피침 형태로 엽연이 자색인 1개종이 수집되었다. 3. 꽃은 화형이 항아리형, 통형, 조롱박형의 3개군으로, 화색은 흰색을 포함한 3개군으로 분류되었으며, 특별하게 조롱박형인 1개 수집종은 연녹색을 띄고 있었다. 화사는 실린더형과 편평형으로, 화경의 색깔은 자색을 포함한 4개군으로 분류되었으며, 포의 존재 유무와 형태에 따라 4개군으로 분류하였다. 4. 과실은 둥근형 등 3개군으로 분류되었으며, 백과중은 둥굴레에서 가장 무거웠던 반면, 용둥굴레에서 가장 가벼웠다. 5. 둥굴레 잎마름병에 대한 저항성이 아주 강한 것은 2종, 이병율이 7% 이하인 것은 7개종으로 조사되어서 근경수량을 증대할 수 있는 저항성 유전자원이 자생하고 있음을 알 수 있었다. 6. 제형질의 상관관계에서 근경수량과 관련된 근경중은 초장, 경직경, 엽수, 엽장, 엽폭, 지하경 직경과 정의상관을 보였으나 근경수량에 가장 큰 영향을 미치는 잎마름병 이병율은 초장, 경직경, 엽수, 엽장, 백립중, 근경중, 지하경 직경과 부의상관을 보였다.

• 대한기계학회논문집A
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• 제24권6호
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• pp.1456-1469
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• 2000

Mechanical behaviors of uniaxially fiber-reinforced metal matrix composites under transverse loading conditions were studied at room and elevated temperatures. A mono-filament composite was selecte d as a representative analysis model with perfectly bonded fiber/matrix interface assumption. The elastic-plastic and visco-plastic models were investigated by both theoretical and numerical methods. The product of triaxiality factor and effective strain as well as stress components and strain energy was obtained as a function of location to estimate the failure sites in fiber-reinforced metal matrix composite. Results showed that fiber/ matrix interfacial debond plays a key role for local failure at the room temperature, while void creation and growth in addition to the interfacial debond are major concerns at the elevated temperature. It was also shown that there would be an optimal diameter of fiber for the strong fiber-reinforced metal matrix composite.

• 한국진공학회지
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• 제12권1호
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• pp.1-6
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• 2003

50 kW급 출력의 전자빔을 발생시킬 수 있는 축선 방식 전자총 (axial electron beam gun)과 전원장치를 제작하였다. 전자총은 전자빔 발생장치와 전자빔 궤적제어장치로 이루어졌다. 전자빔 발생장치는 필라멘트와 음극(cathode), 양극(anode)으로 구성되었고 전자빔의 최대전류는 2A, 가속전압은 평균 25kV이다. 전자빔 궤적제어장치는 전자빔의 크기를 조절하는 초점 (focusing) 코일과 전자빔의 방향을 조절하는 편향(deflection) 코일 및 주사 (scanning) 코일로 구성되었다. 전자총과 별개로 진공용기 내부에 Helmholtz 코일을 설치하여 시료의 표면에 입사되는 전자빔의 입사각도를 최적화시켰다. 각 부분의 동작 특성을 측정한 결과와 제작된 전자총으로 고융점 원소인 지르코늄 (zirconium, Zr)과 가돌리늄(gadolinium, Gd) 금속을 증발시킨 결과를 정리하였다.

• Journal of Korean Vacuum Science & Technology
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• 제3권2호
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• pp.121-125
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• 1999

Vertically well aligned multiwall carbon nanotubes were grown on nickel coated different substrates by plasma enhanced hot filament chemical vapor deposition at low temperatures below 650$^{\circ}C$. Acetylene and ammonia gas were used as the carbon source and a catalyst. The surface roughness of nickel layer increased as NH3 etching time increased. The diameters of the nanotubes decreased and the density of nanotubes increased as NH3 etching time increased. diameter of nanotube was 30 to 70 nm. Nickel cap was observed on the top of the grown nanotube and very thin carbon amorphous layer was fonde on the nickel cap.

• Carbon letters
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• 제8권4호
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• pp.313-320
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• 2007

In the present study, electrospun PAN precursor webs and the stabilized and carbonized nanofiber webs processed under different heat-treatment conditions were characterized by means of weight loss measurement, elemental analysis, scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimentric analysis (TGA), and X-ray diffraction (XRD) analysis. The result indicated that stabilization and carbonization processes with different temperatures and heating rates significantly influenced the chemical and morphological characteristics as well as the thermal properties of the stabilized and then subsequently carbonized nanofiber webs from PAN precursor webs. It was noted that the filament diameter and the carbon content of a carbonized nanofiber web as well as its weight change may be effectively monitored by controlling both stabilization and carbonization processes.