정체류에서 피막전극에 대한 산소의 전달현상

이창우,장호남 한국화학공학회 1979 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.17 No.2

막을 씌운 전극을 사용하여 산소농도를 측정함에 있어서 외부에 stagnation flow를 형성시켰을 때 전류반응을 고찰하였다. stagnation flow에서 산소의 전달현상을 해석하기 위해 몇가지 가정하에 수학적 모델을 세우고 이 결과를 실험치와 비교하였다. 폴리에칠렌 막과 백금전극을 사용한 수용액에의 실험에서는 계산된 유체역학적 boundary layer의 두께가 전극의 반경보다 작거나 거의 같을 때는 유속의 변화에 대한 실험결과는 이론치와 잘 일치한다. 그러나 이보다 커지게 되면 이론치와 실험결과는 많은 차이가 있었으며 이는 일차원적 모델에서 무시되었던 반경방향의 확산이 점차적으로 중요해지기 때문으로 추측된다. 막의 두께가 두꺼워짐에 따라 수용액에서 유체역학적 상황의 변화에 따른 전류응답이 점차적으로 덜 민감해 지는 것을 알 수 있었다. The current response of a membrane covered-electrode with respect to the fluid motion in stagnation flow was investigated in this study. The mathematical model was set up to analyze oxygen transport in this flow regime. The current predicted by the model was compared with the results of the experiments performed using polyethylene film and platinum cathode. One dimensional model was in good agreement with the experimental results when the thickness of hydrodynamic boundary layer was smaller than or comparable to the radius of the electrode, but it did not agree well when the thickness exceeded the radius of the electrode. This may be due to the reason that the radial diffusion term neglected in one dimensional model becomes important as well as the axial diffusion term. It appeared that the current response became less sensitive to the hydrodynamics of the outside of membrane as the thickness of membrane increased.

Low Complexity Decoder for Space-Time Turbo Codes

이창우,Lee Chang-Woo The Korea Institute of Information and Commucation 2006 韓國通信學會論文誌 Vol.31 No.4c

By combining the space-time diversity technique and iterative turbo codes, space-time turbo codes(STTCS) are able to provide powerful error correction capability. However, the multi-path transmission and iterative decoding structure of STTCS make the decoder very complex. In this paper, we propose a low complexity decoder, which can be used to decode STTCS as well as general iterative codes such as turbo codes. The efficient implementation of the backward recursion and the log-likelihood ratio(LLR) update in the proposed algorithm improves the computational efficiency. In addition, if we approximate the calculation of the joint LLR by using the approximate ratio(AR) algorithm, the computational complexity can be reduced even further. A complexity analysis and computer simulations over the Rayleigh fading channel show that the proposed algorithm necessitates less than 40% of the additions required by the conventional Max-Log-MAP algorithm, while providing the same overall performance.

저압 초음파 분무 공정을 이용한 γ-Fe₂O₃ 나노입자의 합성

이창우,김순길,좌용호,이재성,Lee, Chang-Woo,Kim, Soon-Gil,Choa, Yong-Ho,Lee, Jai-Sung 한국분말야금학회 2007 한국분말재료학회지 (KPMI) Vol.14 No.1

This study was focused on the optimization of low-pressure ultrasonic spraying process for synthesis of pure ${\gamma}-Fe_2O_3$ nanoparticles. As process variables, pressure in the reactor, precursor concentration, and reaction temperature were changed in order to control the chemical and microstructural properties of iron oxide nanoparticles including crystal phase, mean particle size and particle size distribution. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies revealed that pure ${\gamma}-Fe_2O_3$ nanoparticles with narrow particle size distribution of 5-15 nm were successfully synthesized from iron pentacarbonyl ($Fe(CO)_{5}$) in hexane under 30 mbar with precursor concentrations of 0.1M and 0.2M, at temperatures over $800^{\circ}C$. Also magnetic properties, coercivity ($H_c$) and saturation magnetization ($M_s$) were reported in terms of the microstructure of particles based on the results from vibration sampling magnetometer (VSM).

Proteomic analysis of human serum from patients with temporal lobe epilepsy

이창우,유승택,최하영,고은정,곽용근 대한소아청소년과학회 2009 Clinical and Experimental Pediatrics (CEP) Vol.52 No.5

Purpose : Epilepsy affects more than 0.5% of the world's population. It has a large genetic component and is caused by electrical hyperexcitability in the central nervous system. Despite its prevalence, the disease lacks definitive diagnostic serological biomarkers. To identify potential biomarkers for epilepsy by a convenient method, we analyzed the expression of serum proteins, reflecting alterations in the patient's proteomes. Methods : We compared two-dimensional electrophoretic band patterns of human sera from eight patients with temporal lobe epilepsy (TLE) with those of eight control subjects. The differentially expressed bands were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization quadrupole time-of-flight mass spectrometry. Results : Twelve proteins were differentially expressed in the TLE group, of which 6 were identified. Expression of haptoglobin Hp2, PRO2675, immunoglobulin heavy chain constant region gamma 2, an unnamed protein, and three unidentified proteins were upregulated in serum from the patients with TLE, whereas those of major histocompatibility complex (MHC) class I antigen, plasma retinol-binding protein precursor, and three unidentified proteins were downregulated in these patients. After resection of the epileptogenic zone, the expressions of MHC class I antigen, immunoglobulin heavy chain constant region gamma 2, two of the downregulated unidentified proteins, and one of the upregulated unidentified proteins returned to the normal range. Conclusion : The 12 serum proteins in this study are potentially useful biomarkers for the diagnosis and monitoring of TLE. Purpose : Epilepsy affects more than 0.5% of the world's population. It has a large genetic component and is caused by electrical hyperexcitability in the central nervous system. Despite its prevalence, the disease lacks definitive diagnostic serological biomarkers. To identify potential biomarkers for epilepsy by a convenient method, we analyzed the expression of serum proteins, reflecting alterations in the patient's proteomes. Methods : We compared two-dimensional electrophoretic band patterns of human sera from eight patients with temporal lobe epilepsy (TLE) with those of eight control subjects. The differentially expressed bands were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization quadrupole time-of-flight mass spectrometry. Results : Twelve proteins were differentially expressed in the TLE group, of which 6 were identified. Expression of haptoglobin Hp2, PRO2675, immunoglobulin heavy chain constant region gamma 2, an unnamed protein, and three unidentified proteins were upregulated in serum from the patients with TLE, whereas those of major histocompatibility complex (MHC) class I antigen, plasma retinol-binding protein precursor, and three unidentified proteins were downregulated in these patients. After resection of the epileptogenic zone, the expressions of MHC class I antigen, immunoglobulin heavy chain constant region gamma 2, two of the downregulated unidentified proteins, and one of the upregulated unidentified proteins returned to the normal range. Conclusion : The 12 serum proteins in this study are potentially useful biomarkers for the diagnosis and monitoring of TLE.

파스콘 트로프의 연기유독성에 관한 연구

이창우,현성호,최돈묵 한국화재소방학회 2006 한국화재소방학회논문지 Vol.20 No.2

The aim of the research is to estimate the effect of smoke and combustion gases on humane body indirectly through measuring the toxicity of those. For this purpose, the toxic index of smoke and combustion gases was investigated by smoke hazard test and analysis of smoke which were conducted by KS F 2271 and NES 713 method respectively. It is proved by KS F 2271 method that PASCON trough is suitable to the testing standard of interior material and construction of building. In addition, it is identified by NES 713 method that combustion gases occurring in PASCON product were only carbon dioxide and carbon monoxide, and the smoke index of those was 0.944. This value means that the hazard effect of smoke gases on humane ! body can possibly happens when exposed to the smoke gases for more than 30 min. In aspect of the domestic situation that have not regulated the hazard estimation and the emissions of smoke when the flame retarding ability of the products have been requested, the toxic indexes of PASCON products are comparatively low. 본 연구는 파스콘 트로프의 화재시 발생되는 연기의 유독성 평가를 위해 KS F 2271에 의한 연기유해 성 시험 및 NES 713방법에 의해 연소가스를 분석하고, 독성지수를 확인해 봄으로서 연소시 인체에 미치 는 영향을 간접적으로 확인해 보고자 한다. 실험결과 파스콘 트로프는 KS F 2271인 건축물의 내장재료 및 구조의 난연성 시험기준에 적합한 것을 확인하였다. NES 713 방법에 의한 파스콘 제품에서 발생하는 연소가스는 이산화탄소와 일산화탄소가 전부임을 알 수 있으며, 연소가스의 독성지수는 0.944로 나타 났다. 이러한 수치는 제품의 연소시 발생되는 연소가스를 30분 이상 노출되어야 위험한 농도에 이룰 수 있다는 것을 의미한다. 난연성능 요구시 연기유독성 평가나 연기의 발생량을 규제하지 않고 있는 국내의 실정에 비추어 볼 때 파스콘 제품의 연소가스 독성지수는 비교적 낮은 수치이다.

Efficient Method to Implement Max-Log-MAP Algorithm: Parallel SOVA

이창우,Lee, Chang-Woo The Korea Institute of Information and Commucation 2008 韓國通信學會論文誌 Vol.33 No.6C

The efficient method to implement the Max-Log-MAP algorithm is proposed by modifying the conventional algorithm. It is called a parallel soft output Viterbi algorithm (SOVA) and the rigorous proof is given for the equivalence between the Max-Log-MAP algorithm and the parallel SOVA. The parallel SOVA is compared with the conventional algorithms and we show that it is an efficient algorithm implementing the modified SOVA in parallel.

정부투자기관 경영성과지표 체계의 균형에 관한 실증분석과 개선방안 연구

이창우 한국회계정보학회 2006 회계정보연구 Vol.24 No.3

(제Ⅰ장)

Physical Properties and Applications of Amorphous W-N Diffusion barriers for 3-D Cu Interconnection

이창우,김수인 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3

Tungsten have been used for via connecting metal at p-n junctions. Therefore, we suggest tungsten- nitride thin films as diffusion barriers for a 3-D Cu interconnect via-hole structure for a system in a package (SiP). The W-N thin lms were deposited with NH3 and WF6 gases and the partial pressure ratio the NH3/WF6 was changed from 0 to 0.9 %, so we had good thermal stability even though the post annealing was carried out at 800 ℃ for 30 min, which was due to the amorphous phase of tungsten-nitride films. The resistivity and the leakage current of the Cu/W-N/Si for the as-deposited state and the annealed state were acceptable for the 3-D interconnect of the system in a package process. Tungsten have been used for via connecting metal at p-n junctions. Therefore, we suggest tungsten- nitride thin films as diffusion barriers for a 3-D Cu interconnect via-hole structure for a system in a package (SiP). The W-N thin lms were deposited with NH3 and WF6 gases and the partial pressure ratio the NH3/WF6 was changed from 0 to 0.9 %, so we had good thermal stability even though the post annealing was carried out at 800 ℃ for 30 min, which was due to the amorphous phase of tungsten-nitride films. The resistivity and the leakage current of the Cu/W-N/Si for the as-deposited state and the annealed state were acceptable for the 3-D interconnect of the system in a package process.

Efficient Conversion of DCT Coefficients to H.264 Transform Coefficients Using Lapped Transforms

이창우 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.7

DCT 영역에서 영상의 임의 비율 크기 변환을 위한 새로운 알고리즘

이창우,김용재 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.2