• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.176.2-176.2
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• 2013

Property of optical diagnostics for pulse-discharged plasma in liquid and its biological applications to proteins are investigated by making use of high voltage Marx generator. The Marx generator has been consisted of 5 stages, where each charging capacitor is 0.5 ${\mu}F$, to generate a high voltage pulse with rising time of $1{\mu}s$. We have applied an input voltage of 6 kV to the each capacitor of 0.5 ${\mu}F$. High voltage pulsed plasma has been generated inside a polycarbonate tube by a single-shot operation, where the breakdown voltage is measured to be 7 kV, current of 1.2 kA, and pulse width of ~ 1 ${\mu}s$ between the two electrodes of anode-cathode whose material is made of tungsten pin, which are immersed into the liquids. We have investigated the emitted hydrogen lines for optical diagnostics of high voltage pulsed plasma. The emission line of 656.3 nm from $H-{\alpha}$ and 486.1 nm from $H-{\beta}$ have been measured by a monochromator. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium conditions, the electron temperature and density of the high voltage pulsed plasma in liquid could be obtained by the Stark broadening of optical emission spectroscopy. For the investigation of the influence of pulsed plasma on biological proteins, we have exposed it onto the proteins such as hemoglobin and myoglobin. The structural changes in these proteins and their analysis have also been obtained by circular dichroism (CD) and ultraviolet (UV) visible spectroscopy.

• 한국산학기술학회논문지
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• 제9권3호
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• pp.615-620
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• 2008

저저항 배선층으로 쓰일 수 있는 선폭 $0.5{\mu}m$, 70nm 높이의 폴리실리콘 패턴에 $10nm-Ni_{1-x}Co_x$(x=0.2, 0.6, and 0.7)의 금속 박막을 열증착법으로 성막하고 쾌속 열처리 (RTA) 온도를 $700^{\circ}C$와 $1000^{\circ}C$로 달리하여 실리사이드화 공정을 실시하여 상부에 니켈코발트 실리사이드를 형성시켰다 이때의 미세구조를 확인하고 FIB (focused ion beam)를 활용하여 저에너지 조건 (30kV-10 pA-2 sec)에서 배선층을 국부적으로 조사하여 실리사이드 층의 선택적 제거 가능성을 확인하였다. 실험 범위내의 실리사이드화 온도 범위와 NiCo 상대 조성 범위에서 주어진 FIB 조건으로 선택적으로 저저항 실리사이드 층의 제거가 가능하였으나, 상대적으로 Co 함유량이 많은 실리사이드는 배선층 내부에서 기포가 발생하였으며, 이러한 기포로 인해 실리사이드 층만의 국부적 제거는 불가능하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.233-233
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• 2010

CdS thin films were deposited on glass substrates by R.F. magnetron sputtering method and some of the samples were treated by rapid thermal annealing (RTA) process. Effects of thermal annealing on structural and optical properties were investigated at different temperatures ranging from 100 to $600^{\circ}C$. The crystallographic structure of the films and the size of the crystallites in the films were studied by X-ray diffraction. The crystallite sizes were found to increase, and the X-ray diffraction patterns were seen to sharpen by annealing. Optical properties of the films were calculated using the envelope method and the photoluminescence measurements. The optical properties of the films were seen to be dependent on the film thicknesses. The energy gap of the films was found to decrease by annealing. The band edge sharpness of the optical absorption was seen to oscillate by thermal annealing. Annealing over $400^{\circ}C$ was seen to degrade the optical properties of the film. The best annealing temperature for the films was found to be $400^{\circ}C$ from the optical properties. It is observed that the CdS film annealed at $400^{\circ}C$ reveals the strongest UV emission intensity and narrowest full width at half maximum among the temperature ranges studied. The enhanced UV emission from the film annealed at $400^{\circ}C$ is attributed to the improved crystalline quality of CdS thin film due to the effective relaxation of residual compressive stress and achieving maximum grain size. The results show that heat treatments under optimal annealing condition can provide significant improvements in the properties of CdS thin films.

• 한국자기학회지
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• 제16권5호
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• pp.229-233
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• 2006

나노 구조 철띠의 자기적 성질을 일반기울기 근사(GGA)를 채택한 전전자 full-potenial linearized augmented plane-wave(FLAPW)에너지 띠 방법을 이용하여 이론적으로 연구하였다. 세 줄, 다섯 줄, 일곱 줄의 철선으로 이루어진 띠에서 가장자리 줄의 자기모멘트는 2.97 또는 2.98 ${\mu}_B$로 Fe 단일 직선의 값과 비슷하게 포화된 값을 가졌으며, 가운데 선의 자기모멘트는 2.82 ${\mu}_B$로 2차원 격자의 값과 같았다. 일곱 줄로 이루어진 철 띠의 전하밀도나 스핀밀도는 가장자리 영역에서 거의 평평한 분포를 보였는데, 이는 가장자리 원자로부터 배출된 p-전자로 인한 가리기에 의한 것이다. 일곱 줄로 이루어진 철 띠에서 가장자리 원자의 상태밀도는 가운데 원자에 비해 띠폭이 줄어들었는데 이는 가장자리 효과에 의한 띠좁힘 때문이다.

• 한국육종학회지
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• 제41권4호
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• pp.510-514
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• 2009

난 시장이 확대되고 있지만 일반대중이 선호하고 있는 동양계 심비디움 난은 대부분 수입 또는 산채에 의존하여 고가로 판매되고 있고, 서양계 심비디움은 외국 품종에 대한 로열티 지불 등의 문제가 대두되고 있다. 본 연구에서는 관상가치가 있고 대량증식이 가능하여 외국산 품종을 대체할 수 있는 소형 심비디움 난을 육성하고자 하였다. 동양계 및 서양계 심 비디움의 교배종인 "동양"의 바이러스 무병주를 생장점배양에 의해 기내에서 대량증식을 하던 중, 잎무늬 돌연변이 식물체를 선발하여 고정계통을 "대국"이라 명명하였다. "대국"은 잎의 가장자리에 백색이나 노란색 줄무늬가 있는 복륜 무늬종으로 광택이 있다. "대국"의 잎 길이는 약 40 cm, 엽폭은 1.6 cm, 엽수는 4~5장으로 동양에 비교하여 잎 및 초세가 작고 단아하다. 꽃에도 복륜무늬가 있으며 개화시기는 3~5월과 9~10월 연 2회이다. 신품종 "대국"은 잎무늬 줄무늬와 초세가 단정하여 분화용 엽예품으로 관상가치가 뛰어나며, 기존 동양계 심비디움 품종에 비교하여 조직배양 및 순화가 잘되고 생육이 왕성하여 값싸게 공급 가능한 품종이다.(품종특허 등록번호: 특허 제 0478734).

• Steel and Composite Structures
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• 제31권6호
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• pp.541-558
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• 2019

In Special Concentrically Braced Frames (SCBFs), vertical and horizontal components of the brace force must be resisted by column and beam, respectively but normal force component existing at the gusset plate-to-column and beam interfaces, creates out-of-plane action making distortion in column and beam faces adjacent to the gusset plate. It is a main concern in Hollow Structural Section (HSS) columns and beams where their webs and gusset plate are not in the same plane. In this paper, a new gusset plate passing through the HSS columns and beams, named as through gusset plate, is proposed to study the force transfer mechanism in such gusset plates of SCBFs compared to the case with conventional gusset plates. For this purpose, twelve SCBFs with diagonal brace and HSS columns and twelve SCBFs with chevron brace and HSS columns and beams are considered. For each frame, two cases are considered, one with through gusset plates and the other with conventional ones. Based on numerical results, using through gusset plates prevents distortion and out-of-plane deformation at HSS column and beam faces adjacent to the gusset plate helping the entire column and beam cross-sections to resist respectively vertical and horizontal components of the brace force. Moreover, its application increases energy dissipation, lateral stiffness and strength around 28%, 40% and 32%, respectively, improving connection behavior and raising the resistance of the normal force components at the gusset plate-to-HSS column and beam interfaces to approximately 4 and 3.5 times, respectively. Finally, using such through gusset plates leads to better structural performance particularly for HSS columns and beams with larger width-to-thickness ratio elements.

• 한국해양공학회지
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• 제32권6호
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• pp.492-501
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• 2018

The following results were obtained from a series of studies to accumulate data to reduce the coefficient of friction for press dies by performing tribological tests before and after the UNSM treatment of SM45C. The UNSM-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those for untreated materials. When loads of 5 N, 7.5 N, and 10 N were applied to the untreated material of SM45C, the coefficient of friction was approximately 0.76-0.78. With the large specimen, a value of 0.72-0.78 was maintained at a load of 50 N despite the differences in the size of the wear specimen and working load. Tribological tests of large specimens of SM45C treated with UNSM under tribological conditions of 100 N and 50 N showed that the frictional coefficient and time constant stably converged between 0.7 and 0.8. The friction coefficients of the small specimens treated with UNSM showed values between 0.78 and 0.75 under 5 N, 7.5 N, and 10 N. The friction coefficients of the SM45C treated with UNSM were comparable to each other.

• 한국해양공학회지
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• 제32권6호
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• pp.502-510
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• 2018

In order to accumulate data to lower the friction coefficient of a press mold, tribological tests were performed before and after coating SM45C with a PVC/PO film and plasma coating (CrN, concept). The ultrasonic nanocrystal surface modification (UNSM)-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those of untreated materials. A comparison of the weight change before and after the tribological test with the CrN and the concept coating material and that of the untreated material showed that the wear loss of the concept coating material and P-UNSM treated material (that is, the UNSM treated material treated with the concept coating) showed a tendency to decrease by approximately 55-75%. Concept 100N had a lower friction coefficient of about 0.6, and P-UNSM-30-100N showed almost the same curve as concept 100N and had a low coefficient of friction of about 0.6. The concept multilayer coating had a thickness of $5.32{\mu}m$. In the beginning, the coefficient of friction decreased because of the plasma coating, but it started to increase from about 250-300 s. After about 350 s, the coefficient of friction tended to approach the friction coefficient of the SM45C base metal. The SGV-280F film-attached test specimen was slightly pushed back and forth, but the SM45C base material was not exposed due to abrasion. The friction coefficient was 0.22, which was the lowest, and the tribological property was the best in this study.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.64-70
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• 2019

In this study, a compact series-fed center-fed open-stub (SFCFOS) linear array antenna for K-band applications is presented. The antenna is composed of a single-line 10-element linear array. A symmetrical Chebyshev amplitude distribution (CAD) is used to obtain a low sidelobe characteristic against a uniform amplitude distribution (UAD). The amplitude is controlled by varying the width of the microstrip patch elements, and open-ended stubs are arranged next to the last antenna element to use the energy of the radiating signal more effectively. We insert a series-fed stub between two patches and obtain a low mutual coupling for a 4.28-mm center-to-center spacing ($0.7{\lambda}$ at 21 GHz). A prototype of the antenna is fabricated and tested. The overall size of the uniform linear array is $7.04{\times}1.05{\times}0.0563{\lambda}_g^3$ and that of the Chebyshev linear array is $9.92{\times}1.48{\times}0.0793{\lambda}_g^3$. The UAD array yields a ${\mid}S_{11}{\mid}$ < -10 dB bandwidth of 1.33% (20.912-21.192 GHz) and 1.45% (20.89-21.196 GHz) for the CAD. The uniform array design gives a -23 dB return loss, and the Chebyshev array achieves a -30.68 dB return loss at the center frequency with gains of 15.3 dBi and 17 dBi, respectively. The simulated and measured results are in good agreement.

• 한국자기공명학회논문지
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• 제22권4호
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• pp.107-114
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• 2018

In this exploration, the nuclear magnetic resonance of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ Single Crystals using FT-NMR spectrometer is investigated. The line width of the resonance line for the $^{207}Pb$ nucleus decreases as temperature increases due to motional narrowing. The chemical shift of $^{207}Pb$ NMR spectra also increases as temperature decreases for both crystals. The spinlattice relaxation times $T_1$ of $^{39}K$ nucleus were calculated as a function of temperature (180 K~400 K). The $T_1$ of $^{207}Pb$ nucleus decreases as temperature increases. The dominant relaxation mechanism at the studied temperature range can be deduced as the Raman process, which is the coupling between lattice vibrations and the nuclear spins. This deduction is substantiated by the fact that the nuclear spin-lattice relaxation rate $1/T_1$ of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystal is proportional to $T^2$, or temperature squared. The activation energies for the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystals are $E_a=49{\pm}1meV$ and $E_a=47{\pm}2meV$, respectively.