• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.414-423
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• 2016

In the present study, the $CuN_x-Cu-CuN_x$ layer the partial pressure ratio Cu metal of Ar and $N_2$ gas using a DC magnetron sputtering device, was generated by the In-situ method. $CuN_x$ layer was able to obtain a surface reflectance reduction effect from the advantages of the process and the external light. $CuN_x$ layer is gas partial pressure, DC the Power, the deposition time variable transmittance in response to the thickness and partial pressure ratio, the reflectance was measured. $Ar:N_2$ gas ratio 10:10(sccm), DC power 0.35 A, was derived Deposition time 90 sec optimum conditions. Thus, according to the optimal thickness and the composition ratio was derived surface reflectance of 20.75%. In addition, to derive the value of ${\Delta}$ Ra surface roughness of 0.467. It was derived $CuN_x$ band-gap energy of about 2.2 eV. Thus, to ensure a thickness and process conditions can be absorbed to maximize the light in a wavelength band in the visible light region. As a result, the implementation of the $12k{\Omega}$ base line resistance of using the Cu metal. This is, 5 inch Metal mesh TSP(L/S: $4/270{\mu}m$) is in the range of the reference operation.

• Bulletin of the Korean Chemical Society
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• v.15 no.5
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• pp.379-386
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• 1994

Reactions of 1',2-bis(diphenylphosphino)-l-(N,N-dimethylaminomethyl)ferrocene (FcNPP) with $M(CO)_6$ (M=Cr, Mo, W) in the presence of TMNO (Trimethylamine oxide) in a stoichiometric ratio of 1 : 1.5 : 3.5 produced a series of Gp 6 metal carbonyl derivatives with a variety of coordination modes: M(CO)$_4({\eta}^2$-FcNPP-P,P) (M=Cr, Mo, W), $M(CO)_5({\eta}^1-FcNPP-P) (M=Mo, W)\;,\; M_2(CO)_9({\eta}^1\;,\;{\eta}^2-FcNPP-P,P,N) (M=Cr, Mo)\;,\;M_2(CO)_{10}({\eta}^1\;,\;{\eta}^1-FcNPP-P,P) (M=Cr, Mo, W)\;, and\;W(CO)_4({\eta}^2-FcNPP(O)-P,N)$. All these complexes were characterized by microanalytical and spectroscopic techniques. In one case, the structure of W(CO)$_4({\eta}^2$-FcNPP(O)-P,N) was determined by X-ray crystallography. Crystals are monocinic, space group P$2_{1/C}$, with a=10.147(2), b=19.902(3), c=19.821(4) ${\AA},\;{\beta}=96.88(2)^{\circ},\;V=3974(l){\AA}^3$, Z=4, and $D_{calc}=1.64 g cm^{-3}$. The geometry around the central tungsten metal is a distorted octahedron, with the nitrogen and phosphorus atoms being cis to each other. Some of these complexes exhibited catalytic activities in the allylic oxidation and epoxidation of cholesterly acetate. Other oxidation products were also formed with the different chemical yields and product distribution depending upon the ligand and the central metal.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.433-440
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• 1986

The direct current polarographic behavior of 4n-BAR in dimethylsulfoxide as an aprotic solvent have been investigated. The reduction of 4n-BAR in 0.05M sodium perchlorate solution proceeds along two one-electron steps to give the corresponding compound containing hydrazo groups, each reduction wave was considerably diffusion controlled and irreversible. By addition of acid HAc to 4n-BAR in DMSO solvent, the two reduction waves have coalesced into one in the condition M $\geq$ mole ratio, acid/reductant(M = 2), the slope of $log(i_d-i)(Mi_d/2-i)/i$/ vs. (-E) is irreversible along one-electron steps reduction waves.

• Journal of information and communication convergence engineering
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• v.5 no.1
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• pp.42-44
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• 2007

The a-Si:H TFTs decreasing parasitic capacitance of source-drain is fabricated on glass. The structure of a-Si:H TFTs is inverted staggered. The gate electrode is formed by patterning with length of $8{\mu}m{\sim}16{\mu}m$ and width of $80{\sim}200{\mu}m$ after depositing with gate electrode (Cr) $1500{\AA}$ under coming 7059 glass substrate. We have fabricated a-SiN:H, conductor, etch-stopper and photoresistor on gate electrode in sequence, respectively. The thickness of these, thin films is formed with a-SiN:H ($2000{\mu}m$), a-Si:H($2000{\mu}m$) and $n^+a-Si:H$ ($500{\mu}m$). We have deposited $n^+a-Si:H$, NPR(Negative Photo Resister) layer after forming pattern of Cr gate electrode by etch-stopper pattern. The NPR layer by inverting pattern of upper gate electrode is patterned and the $n^+a-Si:H$ layer is etched by the NPR pattern. The NPR layer is removed. After Cr layer is deposited and patterned, the source-drain electrode is formed. The a-Si:H TFTs decreasing parasitic capacitance of source-drain show drain current of $8{\mu}A$ at 20 gate voltages, $I_{on}/I_{off}$ ratio of ${\sim}10^8$ and $V_{th}$ of 4 volts.

• Smart Structures and Systems
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• v.17 no.3
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• pp.471-489
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• 2016

Modal identification based on ambient vibration data has attracted extensive attention in the past few decades. Since the excitation for ambient vibration tests is mainly from the environmental effects such as wind and traffic loading and no artificial excitation is applied, the signal to noise (s/n) ratio of the data acquired plays an important role in mode identifiability. Under ambient vibration conditions, certain modes may not be identifiable due to a low s/n ratio. This paper presents a study on the mode identifiability of an instrumented cable-stayed bridge with the use of acceleration response data measured by a long-term structural health monitoring system. A recently developed fast Bayesian FFT method is utilized to perform output-only modal identification. In addition to identifying the most probable values (MPVs) of modal parameters, the associated posterior uncertainties can be obtained by this method. Likewise, the power spectral density of modal force can be identified, and thus it is possible to obtain the modal s/n ratio. This provides an efficient way to investigate the mode identifiability. Three groups of data are utilized in this study: the first one is 10 data sets including six collected under normal wind conditions and four collected during typhoons; the second one is three data sets with wind speeds of about 7.5 m/s; and the third one is some blind data. The first two groups of data are used to perform ambient modal identification and help to estimate a critical value of the s/n ratio above which the deficient mode is identifiable, while the third group of data is used to perform verification. A couple of fundamental modes are identified, including the ones in the vertical and transverse directions respectively and coupled in both directions. The uncertainty and s/n ratio of the deficient mode are investigated and discussed. A critical value of the modal s/n ratio is suggested to evaluate the mode identifiability of the deficient mode. The work presented in this paper could provide a base for the vibration-based condition assessment in future.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.100-100
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• 2016

물리기상증착방법 (Physical vapor deposition)에 의하여 합성된 천이금속 질화물 박막은 경도, 내마모성 등 절삭공구의 성능을 향상시키며, Ti-Al-N, Ti-Zr-N, Zr-Al-N, Cr-Si-N 등의 3원계 경질 박막에 대한 연구가 지속적으로 이루어지고 있다. 이중에서도 CrAlN 코팅은 높은 경도, 낮은 표면 조도 등의 우수한 기계적 특성 이외에 고온에서 안정한 합금상 형성으로 인하여 우수한 내열성을 보유하여 공구 코팅으로의 적용 가능성이 크다. 그러나 최근 공구사용 환경의 가혹화로 인하여 코팅의 내마모성 및 내열성 등의 물성 향상을 통한 공구의 수명 향상이 필요시 되고 있으며, 코팅에 적합한 중간층을 합성함으로써 공구 코팅으로의 적용 가능성을 높이는 연구들이 진행되고 있다. 본 연구에서는 CrAlN 코팅의 물성을 향상시키기 위해 CrAlN 코팅과 WC-Co 6wt.% 모재 사이에 CrN, CrZrN, CrN/CrZrSiN 등의 다양한 중간층을 합성하였으며, 중간층을 포함한 모든 코팅의 두께는 $3{\mu}m$ 로 제어하였다. 합성된 코팅의 미세조직, 경도 및 탄성계수, 내모성을 분석하기 위해 field emission scanning electron microscopy(FE-SEM), nano-indentation, ball-on-disk 마모시험기 및 ${\alpha}-step$을 사용하였다. 코팅의 내열성을 확인하기 위해 코팅을 furnace에 넣어 공기중에서 500, 600, 700, 800, 900, $1,000^{\circ}C$로 30분 동안 annealing 한 후에 nano-indentation을 사용하여 경도를 측정하였다. CrAlN 코팅을 나노 인덴테이션으로 분석한 결과, 모든 코팅의 경도(35.5-36.2 GPa)와 탄성계수(424.3-429.2 GPa)는 중간층의 종류에 상관없이 비슷한 값을 보인 것으로 확인됐다. 그러나, 코팅의 마찰계수는 중간층의 종류에 따라 다른 값을 보였으며, CrN/CrZrSiN 중간층을 증착한 CrAlN 코팅의 마찰계수는 0.34로 CrZrN 중간층을 증착한 CrAlN 코팅의 마찰계수(0.41)에 비해 낮은 값을 보였다. 또한, 코팅의 마모율 및 마모폭도 비슷한 경향을 보인 것으로 보아, CrN/CrZrSiN 중간층을 합성한 CrAlN 코팅의 내마모성이 상대적으로 우수한 것으로 판단된다. 이것은 중간층의 H/E ratio가 코팅의 내마모성에 미치는 영향에 의한 결과로 사료된다. H/E ratio는 파단시의 최대 탄성 변형율로써, 모재/중간층/코팅의 H/E ratio 구배에 따라 코팅 내의 응력의 완화 정도가 변하게 된다. WC 모재 (H/E=0.040)와 CrAlN 코팅(H/E=0.089) 사이에서 CrN, CrZrSiN 중간층의 H/E ratio 는 각각 0.076, 0.083 으로 모재/중간층/코팅의 H/E ratio 구배가 점차 증가함을 확인 할 수 있었고, 일정 응력이 지속적으로 가해지면서 진행되는 마모시험중에 CrN과 CrZrSiN 중간층이 WC와 CrAlN 코팅 사이에서 코팅 내부의 응력구배를 완화시키는 역할을 함으로써 CrAlN 코팅의 내마모성이 향상된 것으로 판단된다. 모든 코팅을 열처리 후 경도 분석결과, CrN/CrZrSiN 중간층을 증착한 CrAlN 코팅은 $1,000^{\circ}C$까지 약 28GPa의 높은 경도를 유지한 것으로 확인 되었고, 이는 CrZrSiN 중간층 내에 존재하는 $SiN_x$ 비정질상의 우수한 내산화성에 의한 결과로 판단된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.117-127
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• 1996

In this paper, we present the bit error performances of 4PSK and 8PSK signal transmission schemes using Maximal Ratio Combining diversity reception for m-distribution and Rician fading channels. The suitability of modeling a Rician fading environment by a properly chosen m-distribution model is examined. Using the error performance of the derived equation has been evaluated and shown in figures as a function of fading index (m), Rician factor (K), diversity branches number (L) and E($E_b/N_o$). It is found that MRC (Maximal Ratio Combining) diversity technique is very efficient for reducing the effects of fading, And then, diversity benifit much large as depth of fading becomes deeper but more decreases as many diversity branchs. Also the results show that the error performance corresponds as much as fading becomes weak and increases with the number diversty branches.

• Journal of Environmental Science International
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• v.13 no.3
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• pp.245-250
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• 2004

The SBR(Sequencing Batch Reactor) process is ideally suited to treat high loading wastewater due to its high dilution rate. SBR operates by a cycle of periods consisting of filling, reacting, settling, decanting and idling. The react phases such as aeration or non-aeration, organic oxidation, nitrification, denitrification and other bio-logical reactions can be achieved in a reactor. Although the whole reactions can be achieved in a SBR with time distributing, it is hard to manage the SBR as a normal condition without recognizing a present state. The present state can be observed with nutrient sensors such as ${NH_{4}}^{+}-N$, ${NO_{2}}^{-}-N$, ${NO_{3}}^{-}-N} and ${PO_{4}}^{ 3-}-P.$ However, there is still a disadvantage to use the nutrient sensors because of their high expense and inconvenience to manage. Therefore, it is very useful to use common on-line sensors such as DO, ORP and pH, which are less expensive and more convient. Moreover, the present states and unexpected changes of SBR might be predicted by using of them. This study was conducted to get basic materials for making an inference of SBR process from ORP(oxidation reduction potential) of synthetic wastewater. The profiles of ORP, DO, and pH were under normal nitrification and denitrification were obtained to compare abnormal condition. And also, nitrite and nitrate accumulation were investigated during reaction of SBR. The bending point on ORP profile was not entirely in the low COD/NOx ratio condition. In this case, NOx was not entirely removed, and minimum ORP value was presented over -300mV. Under suitable COD/NOx ratio which complete denitrification was achieved, ORP bending point was observed and minimum ORP value was under -300m V. Under high COD/NOx ratio, ORP bending point was not detected at the first subcycle because of the fast denitrification and minimum ORP value was under -300mV at the time.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.85-90
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• 2002

$RuO_2$/GaN and related contacts were investigated for Schottky contacts in GaN-Based optical and electronic devices. We demonstrated that an $RuO_2$ film forms a stable Schottky contact on a GaN layer with a barrier height (${\Phi}_B$) of 1.46 eV and transmittance of 70% in the visible and near UV region. $RuO_2$/GaN Schottky diode showed a breakdown at over -50V and leakage current of only 0.3 nA at -5V. The $RuO_2$/GaN Schottky type photodetector had the UV/Visible rejection ratio of over $10^5$ and the responsivity of 0.23 A/W at 330 nm. The $RuO_2$ gate AlGaN/GaN EFET exhibited high drain current ($I_d$) of 689.3 mA/mm and high transconductance ($g_m$) of 197.4 mS/mm. Cut-Off frequency ($f_t$) and maximum operating frequency ($f_{max}$) were measured as 27.0 GHz and 45.5 GHz, respectively.

• Journal of Photoscience
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• v.9 no.2
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• pp.314-316
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• 2002

In halobacterial membrane, pharaonis phoborhodopsin (or pharaonis sensory rhdopsin II, psRII) forms a complex with its transducer pHtrII. Flash-photolyis of D75N mutant did not yield M-intermediate but an O-like intermediate is observed. We examined the interaction between D75N of ppR and t-Htr (truncated pHtrII). These formed a complex in the presence of n-dodecyl-$\beta$-D-maltoside, and the association accelerated the decay of the 0 of D75N from 15 to 56 s$\^$-1/. From the decay time constants under varying ratios of D75N and t-Htr, n, the molar ratio of D75N/t-Htr in the complex, and K$\_$D/, the dissociation constant, were estimated. The value of n was unity and K$\_$D/ was estimated to 146 nM. This K$\_$D/ value can be considered as the association between the photo-intermediate and t-Htr, which is deduced by the method of estimation. Previously we (Photochem. Photobiol. 74, 489-494 (2001)) reported K$\_$D/ of 15 $\mu$M for the interaction between the wild-type and t-Htr by means of the change of M-decay rates. Therefore, this value should be the K$\_$D/ value for the interaction between M of the wild-type and t-Htr.