• 융합신호처리학회논문지
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• 제4권1호
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• pp.49-55
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• 2003

현대산업사회의 발전에 따라 신호처리 분야 중 디지털필터의 사용은 급격히 증가하고 있으며, 특히 디지털 영상처리, 디지털 음성처리, CATV 및 각종 통신 분야 등에서 카메라의 Detail processor, Y/C separator, Ghost제거 필터, 표준변환기(NTSC-PAL), Noise reducer 등으로 많이 사용되고 있다. 이러한 디지털필터에는 일반적으로 IIR(infinite impulse response)과 FIR(finite impulse response) 필터가 있으며, 본 논문에서는 구현이 용이하고 선형위상특성을 갖는 FIR 디지털필터를 설계하였다. FIR 디지털필터 설계에 있어서 통과대역의 차단주파수 부근에서 깁스(gibbs) 현상에 의해 생긴 리플을 완화하기 위해 window함수를 사용한다. 그러나, 기존의 window는 고정된 값으로 되어 있으므로 설계목적에 적합한 window함수를 선택함에 있어 다소 문제점이 있다. 따라서, 본 논문에서는 설계목적에 따라 서 융통성있게 선택이 가능한 파라메터를 부가한 변형된 Hanning window를 설계하였으며, 타당성을 입증하기 위해 디지털필터를 설계하여 기존의 Hamming, Hanning, Blackman, Kaiser window와 비교하였으며, 판단기준으로 peak side-lobe와 천이특성 등을 사용하였다.

• 대한금속재료학회지
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• 제50권4호
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• pp.331-337
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• 2012

Electrical properties as a function of composition in silicon nitride ($SiN_x$) films grown at low temperatures ($<200^{\circ}C$) were studied for applications to photonic devices and thin film transistors. Both silicon-rich and nitrogen-rich compositions were successfully produced in final films by controlling the source gas mixing ratio, $R=[(N_2\;or\;NH_3)/SiH_4]$, and the RF plasma power. Depending on the film composition, the dielectric and optical properties of $SiN_x$ films varied substantially. Both the resistivity and breakdown field strength showed the maximum value at the stoichiometric composition (N/Si = 1.33), and degraded as the composition deviated to either side. The electrical properties degraded more rapidly when the composition shifted toward the silicon-rich side than toward the nitrogen-rich side. The composition shift from the silicon-rich side to the nitrogen-rich side accompanied the shift in the photoluminescence characteristic peak to a shorter wavelength, indicating an increase in the band gap. As long as the film composition is close to the stoichiometry, the breakdown field strength and the bulk resistivity showed adequate values for use as a gate dielectric layer down to $150^{\circ}C$ of the process temperature.

• 대한금속재료학회지
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• 제48권4호
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• pp.320-325
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• 2010

NiO thin films were deposited by radio frequency magnetron sputtering on glass substrates. The processing variables of the oxygen content, sputtering power, and pressure were varied to investigate the electrical properties and surface morphology of NiO films. It was found that the resistivity of NiO films at $1.22{\times}10^2{\Omega}cm$ (2.5% $O_2$ in Ar gas) was greatly reduced to$ 2.01{\times}10^{-1}$ ${\Omega}cm$ (100% oxygen) under a typical sputtering condition of 6 mTorr and 200 watts. In an effort to observe the resistivity variances, the sputtering power was varied from 80 to 200 watts at 6 mTorr with 100% $O_2$. However, the resistivity of the NiO films changed in the range of $10^{-1}-10^{-2}$ ${\Omega}cm$. The dependence on the sputtering power was therefore found to be weak in this experiment. When the sputtering pressure was changed from 3 to 60 mTorr at 200 watts with 100% $O_2$, the resistivity of the NiO films showed the lowest value of $5.8{\times}10^{-3}$ ${\Omega}cm$ at 3 mTorr, which is close to that of commercial ITO films (${\sim}10^{-4}$ ${\Omega}cm$). As the sputtering pressure increased, the resistivity also increased to 4.67 cm at 60 mTorr. The surface morphology of the NiO films was also checked by Atomic Force Microscopy. It was found that the RMS surface roughness values ranged from 0.6 to 1.5 nm and thtthe dependence on the sputtering parameters was weak.

• 한국식품저장유통학회지
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• 제25권1호
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• pp.62-70
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• 2018

생맥산의 이화학적 특성 및 생리활성을 향상시키기 위해 주 재료 중 하나인 맥문동을 0(S-0, 대조군), 30(S-30), 60(S-60), 90(S-90)분간 건열 덖음 처리하여 생맥산을 제조한 후 유효성분 및 항산화 활성을 분석하였다. 생맥산의 색도 중 L 값은 S-0에서 가장 높았으며, 덖음 처리 시간이 증가함에 따라 유의적으로 감소하였다. 생맥산의 a 값과 b 값은 대조군보다 덖음 처리한 맥문동 첨가군들에서 낮았지만, 덖음 처리 시간에 따른 경향성을 보이지는 않았다. 생맥산의 가용성 고형분의 함량($7.10{\pm}0.0^{\circ}Brix$)과 환원당 함량($37.32{\pm}0.05g/100g$)은 S-60에서 가장 높고, pH와 산도는 모든 조건에서 유의적인 차이가 없었다. 생맥산의 총 페놀 화합물 함량은 맥문동의 덖음 처리 시간이 증가함에 따라 유의적으로 증가하여 S-90에서 $345{\pm}0.34mg/100g$으로 정량되었으며, 총 플라보노이드 함량은 S-0에서 가장 높고 S-60에서 감소하였지만 S-90과 유의적인 차는 없었다. 생맥산의 총 안토시아닌 함량은 오미자에서 용출된 것이기 때문에 대조군과 덖음 처리한 맥문동 첨가군에서 차이가 없었다. 생맥산의 총 진세노사이드(Ro, Rb2, Re, Rf, Rg1, Rg2, Rg3, Rh1, Rh2) 함량은 차이가 없었지만, Ro, Re, Rf, Rb2, Rh2, Rg3는 S-0과 S-90을 비교하였을 때 당과 물 분자의 제거 정도에 따라 고분자에서 저분자 진세노사이드로 변형되어 그 함량이 증가하거나 감소하였다. 생맥산의 DPPH와 ABTS 라디칼 소거능 및 FRAP법에 따른 항산화 활성은 맥문동의 덖음 처리 시간이 증가함에 따라 뚜렷하게 증가하는 경향이었다. 이상의 결과로부터 생맥산의 유효성분은 맥문동을 1시간 정도로 적절히 덖음 처리하였을 때 가장 높고, 항산화 활성은 맥문동의 덖음 처리 시간이 증가할수록 높아지는 것을 확인할 수 있었다.

• 한국농림기상학회지
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• 제24권3호
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• pp.164-178
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• 2022

주요 곡물 생산 지역에 대한 작황 계절 예측을 위해 작물모형과 기상 예보자료들이 활용되고 있다. 이 때, 작물모형의 입력자료로 활용되는 기상자료의 불확실성이 작황 예측 결과에 영향을 줄 수 있다. 본 연구에서는 기상 예보자료에 따른 작물모형 결과에 미치는 영향을 알아보고자 하였다. 주요 곡물 생산 지역인 미국의 콘벨트 지역을 대상으로 중규모 수치예보 모형인 Weather Research and Forecasting (WRF)로 10km 해상도의 계절 예측 자료를 생산하였다. 보다 상세한 기상 예보자료 생산을 가정하기 위해 통계적 기법인 Parameter-elevation Regressions on Independent Slopes Model (PRISM) 기법을 활용하여 WRF 자료를 기반으로 5km 해상도로 예측 자료를 생산하였다. WRF와 PRISM 계절 예측 자료로 CROPGRO-SOYBEAN 모형을 구동하여 두 기상 예보자료에 따른 작물 생육 모의 결과를 얻었다. 2011~2018 기간에 대하여 4월 10일부터 8일 간격으로 11개의 파종일을 설정하였으며, 3개의 콩 성숙군에 대한 품종 모수가 사용되었다. 기상 자료의 불확실성을 파악하기 위해 작물 재배기간 동안의 누적 생육도일과 누적 일사량을 비교하였다. 예측된 수량 및 성숙일 등의 주요 변수들을 비교하였다. 두 기상 자료로부터 얻어진 변수들 사이의 일치도 통계량 계산을 위해 root mean square error (RMSE), normalized root mean square error (NRMSE) 및 structural similarity(SSIM) index가 사용되었다. WRF와 PRISM에서 계산된 누적 생육도일 사이의 일치도가 낮았던 연도에 콩 성숙일 모의 값에 대한 오차가 크게 나타났다. 콩 모의 수량 또한 성숙일 및 온도의 오차가 크게 나타났던 연도에 상대적으로 낮은 일치도를 가졌다. 또한 파종일이 수량 및 성숙일 예측의 일치도에 상당한 영향을 미치는 것으로 나타났다. 이러한 결과는 WRF와 PRISM 자료 사이에 온도 자료의 불확실성이 작황 예측의 불확실성에 영향을 주었으며, 재배 시기에 따라 그 불확도의 크기가 상이할 수 있음을 암시하였다. 따라서 신뢰도 높은 작황 예측 자료 생산을 위해 작물별 재배기간을 고려한 불확실성 평가 등의 추가적인 연구가 진행되어야 할 것으로 보인다.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.105-114
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• 1999

목련 각 부위의 에탄올추출물과 분별물 및 잎 부위에서 단리한 리그난류의 항균활성 검정 결과, 포자발육저해의 성분은 각 부위에 걸쳐서 특히 석유에테르 가용부, 에테르 가용부에 집중되어 있었다. 여기서 효과를 갖는 리그난은 (-)syringaresinol(X III), medioresinol(VI), phillygenin(VIII), kobusinol A(X)이었는데, 이들은 모두 구조적으로는 guaiacyl 및 syringyl의 골격을 갖는 페놀성 수산기의 특징을 보여 주었다. 추출물 및 분별물의 항미생물 활성은 석유에테르 가용부에서 가장 강한 억제효과가 있었다. 공시균에 대한 리그난류의 성장저해 효과는 그다지 현저하지는 않았지만, 이들 리그난류를 함유하는 추출물 및 각 분별물은 리그난과의 상승효과를 보였다.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1987년도 Proceedings of Korea-Japan Panax Ginseng Symposium 1987 Seoul Korea
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• pp.29-37
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• 1987

This study was devised to observe the cytotoxlc activities of petroleum-ether extract of Panax ginseng root(crude Gx) and its partially purified fraction from silicon acid column chromatography(7:3 CX) against sarcoma-180(5-180) and Walker carcinosarcoma 256(Walker 256) in vivo, and murine leukemic lymphocytes(L1210) and human rectal cancer cell(HRT-18) and human colon cancer cells(HT-29 and HCT-48) in vitro . Each cell-line was cultured in medium containing serial concentrations of the crude Gx or 7:3 Gx in vitro. A highly lipid soluble compound in the extract of Panax ginseng root was cytocidal to murine leukemic cells and human colon and rectal cancer cells in vitro In the meantime, ginseng saponin derivatives did not cytotoxic effects at its corresponding concentration. The growth rates of the cancer cells in medium containing ginseng extracts were inhibited gradually to a significant degree roughly in proportion to the increase of the extract concentration. The cytotoxic activity of 7:3 Gx was about 3 times more potent than that of crude Gx, one unit of cytotoxic activity against L121f cells being equivalent to 2.54$\mu\textrm{g}$ and 0.88 $\mu\textrm{g}$ for the crude Gx and 7:3 Gx, respectively. The Rf value of the active compound on silica -gel thin layer chromatography with petroleum-ether/ethyl ether/acetic acid mixture (90:10:1, v/v/v) as a developing solvent was 0.23. The survival times of mice inoculated with S-180 cells were extended about 1.5 to 2 times by the 7:3 Gx treatment compared with their control group. The significantly decreased hemoglobin values of rats after inoculation with Walker 256 were recovered to normal range by oral administration of the crude Gx. The synthetic levels of protein, DNA and RNA in human colon and rectal cancer cells were significantly diminished by treatment with the crude Gx, which can explain a part of the origin of its anticancer activity.

• 한국환경보건학회지
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• 제5권1호
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• pp.46-50
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• 1978

Aflatoxin, a mixture of the at least four toxic and carcinogenic metabolites, is known to be produced by only a few fungi. The toxins were designated aflatoxins because they were produced by the mold Aspergillus flavus(A. flavus). However, at least four other toxins and other species of the genus A. niger, A. parasiticus A. ruber and wentii have been reported to produce aflatoxins. And also the identical compounds may also be produced by molds, the Pencillium. At least four different species of Penicilliurn have been reported to produce aflatoxins (P. citrinurn, P. frequentans, P. puberulurn. and P. variable). So it is now known that the problem of Aflatoxin is not restricted to the single species A. flavus, even though that is a very common mold. Also additional aflatoxins have been discorvered. For sereral years, only four aflatoxins were known: $B_1, B_2, G_1$ and $G_2$, so designated by reason of their fluorescence and chromatographic charateristics. It is now known that there are really two new toxic materials in the milk. During the past year(1966) they were christened aflatoxin $M_1$ and $M_2$, since they were first found in milk. The two other and most recently discorvered aflatoxins were isolated late in 1966 from cultures of A. flavus, and were designated aflatoxin $B_2a$ and aflatoxin $G_2a$. In order to obtain a breaf information about extent of contamination of foodstuffs by aflatoxin which is known to produce eight different mold, aflatoxin detection of cereals and fermented foods on sale, such as polished rice, barley, wheat, wheat flour, lentil, red bean, soy bean, noodle, kochuj ang and Dwenjang (fermented soy bean paste) and chong Kuk, were carried out. The results of this investigation were summarized as follows: The hexane:$CHCl_3$ extracts of polished rice, barley wheat, wheat flour, lentil, red bean, noodle and kochujang yielded fluorescent spots on thin layer plates. However their Rfvalues were different from those of authentic aflatoxins. The fluorescent substances of the extract from soy bean, Dwenjang and chong kuk showed very similar Rf values to those of the standard aflatoxins. By two dimensional thin layer chromatography and comparison of ultra violet absorption spectra, it was found that these fluorescent substances were not aflatoxins. To conclude, aflatoxins themselves were not detected directly in those samples tested.

• 한국식품과학회지
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• 제10권2호
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• pp.194-202
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• 1978

In order to evaluate the utility of the anthocyanin pigments in Ganges Amaranth as an edible pigment, this study was designed to isolate and identify the anthocyanins. The anthocyanins present in leaves of Ganges Amaranth were extracted with 0.1% HCl in methanol. The extracted pigments were purified by organic solvent treatment and Amberlite CG-400 Type cation exchanger, and then separated into individual pigments by paper chromatography with n-butanol-formic acid-water(100:25:60, v/v) as a solvent system. The separated pigments were identified by their Rf values, sugar moieties, complete hydrolysis and spectral characteristics in the visible and ultraviolet regions. The amounts of individual anthocyanins were also determined. The results obtained from these experiments were as follows. 1. Chromatograms of the Ganges Amaranth extract developed with BFW yielded three anthocyanin bands. The two of the anothocyanin bands were tentatively identified as malvidin-3-glucoside(acylated with caffeic acid) in band 1 and peonidin-3-glucoside (acylated with caffeic acid) in band 2. But the anthocyanin in band 3 was not identified due to extremly low concentration. 2. The amount of total anthocyanins was 101.57 mg/100g fresh weight of leaves in which 82.15 mg of malvidin-3-glucoside (acylated with caffeic acid) and 27.20 mg of peonidin-3-glucoside(acylated with caffeic acid) were contained per 100g fresh weight. Maividin-3-glucoside acylated with the acid was, therefore, the most abundant pigment in the Ganges Amaranth.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.