• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.4
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• pp.23-28
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• 2004

In this paper, the properties of Mo as PMOS gate electrodes were studied. The work-function of Mo extracted from C-V characteristic curves was appropriate for PMOS. To identify the electrical and chemical stability of Mo metal gate, the changes of work-function and EOT(Effective Oxide Thickness) values were investigated after 600, 700, 800 and 90$0^{\circ}C$ RTA(Rapid Thermal Annealing). Also it was found that Mo metal gate was stable up to 90$0^{\circ}C$ with underlying SiO$_2$through X-ray diffraction measurement. Sheet resistances of Mo metal gate obtained from 4-point probe were less than 10$\Omega$/$\square$ that was much lower than those of polysilicon.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.312.2-312.2
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• 2014

실리콘은 광센서, 태양전지, 발광다이오드 등 광소자 응용 분야에서 널리 사용되고 있는 물질이다. 그러나 실리콘의 높은 굴절율(n~3.5)은 표면에서 약 30% 이상의 Fresnel 반사를 발생시켜 소자의 효율을 감소시키는 원인이 된다. 따라서, 반사손실을 줄이기 위해서는 실리콘 표면에 효율적인 무반사 코팅을 필요로 한다. 기존의 단일 혹은 다중 박막을 이용한 무반사 코팅 기술은 물질간 열팽창계수의 불일치, 접착력 문제, 박막 두께 조절 및 적합한 굴절율을 갖는 물질 선택 어려움 등의 단점을 지니고 있다. 최근, 이러한 무반사 코팅 기술의 대안으로 곤충 눈 구조를 모방한 나노크기의 서브파장 격자구조 (subwavelength gratings, SWGs)에 대한 연구가 활발히 이루어지고 있다. 이러한 SWGs 구조는 공기와 반도체 표면 사이에 점진적, 선형적으로 변화하는 유효굴절율을 갖기 때문에, 광대역 파장영역뿐만 아니라 다양한 각도에서 입사하는 빛에 대해서도 효과적으로 Fresnel 표면 반사를 낮출 수 있다. 본 연구에서는 실리콘 기판 표면 위에 효율적인 무반사 특성을 갖는 계층적 SWGs 나노구조를 제작하기 위해, 레이저간섭리소그라피 및 열적응집금속 입자를 이용한 식각 마스크 패터닝 방법과 유도결합플라즈마 식각 공정을 이용하였다. 제작된 무반사 실리콘 SWGs 나노구조의 표면 및 식각 프로파일은 전자주사현미경으로 관찰하였고, 표면 접촉각 측정 장비를 이용하여 샘플 표면의 젖음성을 확인하였다. 제작된 샘플의 광학적 특성을 조사하기 위해 UV-vis-NIR 스펙트로미터와 엘립소미터 측정 시스템들을 이용하였다.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.157-162
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• 1995

A reservoir located at Chollanam-do province was selected to estimate annual deposition rate, volume of annually deposited material, and annual soil loss from the watershed using Cs-137 redistribution. Sediment profiles of the reservoir indicated an average annual deposition rate of 1.56 cm $yr^{-1}$ and the total deposited volume of $166530\;m^3$ since 1963/64. Annual soil loss from the watershed was 25 ton $ha^{-1}$. Particle size analysis showed that most of the particles were silt-sized ones.

• Journal of the Korean Ceramic Society
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• v.37 no.9
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• pp.847-855
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• 2000

80$0^{\circ}C$에서 작동하는 중온형 SOFC(Solid Oxide Fuel Cell) 단전지의 제조공정을 확립하고 그 출력특성을 평가하였다. 중온형 SOFC에서 문제가 되는 전해질 성분에 의한 출력 감소를 최소화하기 위해 음극기판 위에 7-15$\mu\textrm{m}$ 두께의 얇은 YSZ막을 입히는 음극지지형 SOFC를 구성하였다. 산화, 환원 반응이 일어나는 전극에서는 전극반응에 필요한 유효면적을 최대화하여 분극 저항을 줄일 수 있도록 음극으로는 Ni-YSZ 복합체를, 양극으로는 LSM-YSZ 복합체를 사용하였다. 출력특성 평가를 위한 단전지 홀더는 Inconnel을 가공하여 사용하였으며 80$0^{\circ}C$에서 최적의 밀봉효과를 나타낼 유리밀봉재를 개발하여 사용하였다. 제조한 단전지의 단면적은 5$\times$5$\textrm{cm}^2$, 10$\times$10$\textrm{cm}^2$ 두 종류였으며 운전 시험결과 5$\times$5 단전지의 경우는 최고 0.2W/$\textrm{cm}^2$, 10$\times$10 단전지의 경우는 0.12W/$\textrm{cm}^2$ 정도의 출력밀도를 나타내었다. 단전지의 출력 및 장기 안정성은 전극구조의 변화 및 단전지 홀더의 산화에 따른 접촉 저항 변화에 크게 영향을 받는 것으로 나타났으며 운전중의 연료공급 및 작동온도 변화 등에 의한 영향도 큰 것으로 나타났다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.903-910
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• 1998

Ti:LiNbO$_3$ optical waveguides have been fabricated by Ti-diffusion in wet oxygen atmosphere. The fabrication conditions of furnace temperature, diffusion time and bubbler temperature were 105$0^{\circ}C$, 8 hours and 9$0^{\circ}C$, respectively and Ti thickness was varied from 700$\AA$ to 1500$\AA$. In this paper, the nearfield patterns, mode sizes (hirizontal/vertical) and insertion loss of waveguides were discussed at wavelength 1550 nm ad function of Ti thickness. With the planar waveguide, the effective index change and diffusion depth were calculated at 632.8nm using the prism coupling method. From these results, the best Ti thickness in our conditions seems like to by 1200$\AA$~1300$\AA$.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1027-1030
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• 2011

휴머노이드 로봇 중 초상화를 그리는 로봇이 있지만 다양한 영상을 입력받아 명암 및 그림자까지 그림을 그리는 로봇은 흔하지 않다. 기존의 화가로봇들은 사용자의 얼굴을 영상으로 입력받아 윤곽선만 추출하여 그리는 방식으로, 입력된 영상으로부터 로봇 암을 제어하는 과정에서 제대로 동기화가 이뤄지지 못해 드로잉 속도가 느리고 원본 영상과 비교 시 차이가 많이 난다. 본 연구에서는 입력된 영상으로부터 명암과 그림자를 인식하여 표현해 줌으로써 입체감 있는 그림의 드로잉이 가능하다. 또한, 로봇 암의 미세한 컨트롤을 통해 드로잉 선 두께를 제어함으로써 자연스러운 그림을 그리고, 드로잉 속도가 향상되어 정확도를 높일 수 있게 하는 휴리스틱 암 제어 기술을 제안한다. 이를 구현하기 위해서는 영상으로부터 명암, 그림자의 농도에 따라 레벨을 결정하고, 레벨을 바탕으로 주변 명암 픽셀들을 평활화 하여 좌표 집합을 추출한다. 좌표 값들로 부터 유효 궤적을 분석하여 로봇 암이 이동할 경로를 추출하고, 효율적인 드로잉 기법을 통해 명암을 표현하여 드로잉하려 한다.

• Progress in Medical Physics
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• v.14 no.4
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• pp.218-224
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• 2003

Purpose：By evaluating the dependence of the tray transmission factor (tray factor) on collimator setting and tray thickness, we determined the validity of the clinically used single tray factor for standard radiation field size (10${\times}$10 $\textrm{cm}^2$). Methods and Materials：For each X ray energies (6 and 10 MV), outputs were measured by using 5 steps of tray thickness (0, 6, 8, 10, 12 mm) and 7 steps of radiation field size (5${\times}$5, 10${\times}$10, 15${\times}$15, 20${\times}$20, 25${\times}$25, 30${\times}$30, 35${\times}$35 $\textrm{cm}^2$) at 10 cm phantom depth. Outputs were measured in both 'with tray' and 'without tray' conditions by using radiation with the same monitor units, and the tray factors were determined by the ratios of the two outputs. To evaluate the validity of a single tray factor obtained for standard radiation field, we analyzed the pattern of the field sizes in cases treated at our hospital in 2002. Results : In the 6 MV X-ray, the increases in the tray factor between the standard field (l0${\times}$10 $\textrm{cm}^2$) and the largest field (35${\times}$35 $\textrm{cm}^2$) were 0.517%, 0.835%, 1.058%, 1.066% in 6, 8, 10, and 12 mm thickness tray, respectively. In the 10 MV X-ray, the increases in the fray factor between the standard field (10${\times}$10 $\textrm{cm}^2$) and the largest field (35${\times}$35 $\textrm{cm}^2$) were 0.517%, 0.836%, 1.058%, 1.066% in 6, 8, 10, 12 mm thickness tray, respectively. In a major portion of clinical cases, when the field size was smaller than 20${\times}$20 $\textrm{cm}^2$, the tray factor was in good agreement with the standard tray factor. However, in cases where the field sizes were 30${\times}$30 $\textrm{cm}^2$ and 35${\times}$35 $\textrm{cm}^2$, the error could exceed 1.0%. Conclusion：The tray factor increased with increasing field size or decreasing tray thickness. The difference of tray factor between the small field and the large field increased with increasing tray thickness. Furthermore, the standard tray factor was valid in most clinical cases except for when the field size was greater than 30${\times}$30 $\textrm{cm}^2$, wherein the error could exceed 1.0%.

• Journal of Life Science
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• v.27 no.4
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• pp.383-389
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• 2017

This study intends to analyze the contents of rutin, procyanidin B3, quercetin, kaempferol, known to have antioxidant, anti-inflammatory and anti-carcinogenic effects, among the polyphenol type contained in the grape pruning stem extracts (GPSE), utilizing grape stems being discarded after harvest, measure the effects on the skin moisture, inhibition of skin cell proliferation, anti-inflammatory on the damaged skin of a HR-1 mice induced with UVB, and verify the applicability as a material for functional food and functional cosmetics. The results of verifying the photoprotection effects through the skin proliferation control through of GPSE showed similar result to suncream was achieved at the GPSE concentration of 2,000 mg/kg on the epidermis (p<0.05). The results showed anti-inflammatory effects on all groups applied with GPSE as compared to the control group irradiated with UVB, but at the GPSE concentration of 1,000 mg/kg, a lower COX-2 protein expression at 8%, lower than the 22% of suncream, was observed to achieve an excellent anti-inflammatory effect (p<0.05). The results of this study confirmed the existence of active polyphenol type, such as rutin, kaempferol, querocetin and procyanidin B3, within the GPSE, and GPSE has improvement effects on moisturizing effects, skin proliferation control effect, inflammatory control effect and improvement effects on the skin barrier function through UV ray damage. GPSE is a functional ingredient with a potential for skin protection effects, and has high utilization as an ingredient for functional food and functional cosmetics.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.342-352
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• 2023

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20℃ temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 µmol m^-2 s^-1. The kale plants were then transferred to two chambers with different CO₂ concentrations (382±3.2 and 1,027±11.7 µmol mol^-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m^-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO₂ were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO₂ environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO₂ environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.44-49
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• 2012

Purpose: In the whole body PET/CT scan, it is natural to lift the patient's arm for its quality improvement. However, when the lesion is located in head and neck, the arms should be located lower. This study was designed to compare the CT effective dose for each arm position applying Automatic Exposure Control (AEC). Materials and Methods: 45 patients who had $^{18}F$-FDG whole body PET/CT scan were studied with Biograph Truepoint 40 (SIEMENS, GERMANY), Biograph Sensation 16 (SIEMENS, GERMANY), Discovery STe 8 (GE healthcare, USA). The CT effective dose of 15 patients for each equipment was measured and comparatively analyzed in both arm-lifted position and lower-arm position. ImPACT v1.0 program was used as the method of measurement for CT effective dose. For the statistics analysis, Paired t-test which paired with SPSS 18.0 statistic program was applied. Results: In the case of arm-lifted, it was measured as $6.33{\pm}0.93mSv$ for Biograph Sensation 16, $8.01{\pm}1.34mSv$ for Biograph Truepoint 40, and $9.69{\pm}2.32mSv$ for Discovery STe 8. When arms are located lower position, it was measure as $6.97{\pm}0.76mSv$, $8.95{\pm}1.85mSv$, $13.07{\pm}2.87mSv$ for each. CT effective dose according to the arm position was 9.2% for Biograph Truepoint 40, 10.5% for Biograph Sensation 16, and 25.9% for Discovery Ste 8. The statistics analysis showed the meaningful difference ($p$<0.05). Conclusion: For the whole body PET/CT case, CT effective dose applying AEC was decreased the radiation exposure of the patients when the arm was lifted for 15.2% of average value. The patient who has no lesion in head and neck would decrease the artifact occurrence in objective part and lower the CT effective dose. Also, for the patient who had lesion in head and neck, the artifact in objective part can be lower by putting the arms down, the fact that CT effective dose increases should be concerned in its whole body PET/CT scan.