수중 음향 수신기에의 용응을 위한 DIC-노취 필터에 관한 연구

차일환,신동찬 연세대학교 산업기술연구소 1981 논문집 Vol.13 No.1

본 논문에서는 아나로그 노취필터의 전달함수를 디지탈 노취필터의 전달함수로 전환하는데, 쌍일차 변환법(bilinear trans-formation)이 사용된다. DIC(Digital incremental computer)에 의해서 실현된 노취필터는 낮은 반올림 2차(round-off error)와 시스템의 강도(sensitivity)를 가지며, 극점들이 Z=+1부근에 존재하므로 안정성이 높다. 노취주파수와 3-dB소거 대역폭을 매개변수로 하는 디지탈 노취필터의 실현방법으로는 승산기 추출접근법(multiplier extraction approach)이 이용되었다. 이와같은 방법으로 실현된 16개의 노취필터중, 수중음향 탐지신호 처리시스템으로써 최적필터는 DIC-노취필터-A형 임이 보여졌다. In this paper, the bilinear-transformation was applied to the analog transfer- function order to develop a suitable transter-function for the digital notch filter. A notch filter structure, based on DIC is proposed, which has low sensitivity, minimum errorch-aracteristics, and good stability. A recursive digital notch filter is characterized by two distinct parameters, that's what, the notch frequency and 3-dB rejection bandwidth. A multiplier-extraction approach to the DIC-notch filter realization problem was proposed. The best optimal system that processes the sonar signal was found to be DIC-notch filter-A type.

한국어 화자 인식에 관한 연구

김영일,차일환 연세대학교 산업기술연구소 1985 논문집 Vol.17 No.1

This experiment is performed for the vowel part of 84 Korean syllables and two linear prediction coefficient, partial autocorrelation coefficient and formant as characteristic parameter. In speaker recognition, for self test the recognition scores of linear prediction coefficient, partial autocorrelation coefficient and formant are 95.2(%), 92.9(%) and 97.6(%) respectively, and for reference test, recognition scores of linear prediction coefficient and partial autocorrelation coefficient are 50.6(%) and 57.1(%) respectively.

한국어 음성 인식에 관한 연구

이창섭,차일환,김영일 연세대학교 산업기술연구소 1984 논문집 Vol.16 No.2

In this study, a system is proposed which can be used for recognition of Korean single vowels "ㅏ, ㅓ, ㅗ, ㅜ, ㅡ, ㅣ, ㅐ, ㅔ, ㅚ" and automatic recognition is processed using μ-computer. 3 men of not-being-studied are participated in this experiment. Using the period of vowels, one part of the steady state is selected for high speed recognition, and LPC, PARCOR and formant are used for parament of recognition. Formant is obtained by peak picking method using LPC, and then vowels are recognized by LPC, PARCOR, formant. As a result, recognition rates are 93.1% for LPC, 100% for PARCOR, 88.8% for using formant.

單一反射音의 最適遲延時間

강성훈,임광호,차일환 연세대학교 산업기술연구소 1983 논문집 Vol.15 No.2

Subjective preference tests with a simulated single reflection in an anechoic chamber were performed in order to find the preferred delay time of the first reflection in the musical sound field. The preferred time delay gap between the direct sound and the first reflection can be determined by the interval of coherence of music and the amplitude of the reflection. The scale value of subjective preference is formulated in terms of the 1.2 power of the normalized parameter which is expressed in the logarithm. This observation is taken into consideration in the design stage of concert halls and in selecting music to be performed in a given concert hall.

성문에 의한 화자 인식에 관한 연구

조병모,윤대희,차일환 연세대학교 산업기술연구소 1989 논문집 Vol.21 No.2

Preliminary experiments of using the LPC parameter for text-independent speaker identification problem are presented. The identification process includes log likelihood ratio for distance measure and dynamic programming for time normalization. To generate the data base for experiments, ten speakers were asked to utter the same sentence ten times. Experimental results show 99.4% of identification accuracy. Incorrect identification were made when the speaker uses a dialect.

Anti-inflammatory potential of saponins derived from cultured wild ginseng roots in lipopolysaccharide-stimulated RAW 264.7 macrophages

GYEONG-JIN, YU,IL-WHAN, CHOI,GI-YOUNG, KIM,BYUNG-WOO, KIM,CHEOL, PARK,SU-HYUN, HONG,SUNG-KWON, MOON,HEE-JAE, CHA,YOUNG-CHAE, CHANG,KEE YOEUP, PAEK,WUN-JAE, KIM,YUNG HYUN, CHOI UNKNOWN 2015 INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE Vol.35 No.6

<P>Ginseng, namely the root of Panax ginseng Meyer, is a well-known traditional medicine that has been used in Asian countries for thousands of years. Ginseng saponins have been shown to exert a variety of prominent pharmacological effects in a number of diseases. The aim of the present study was to identify the anti-inflammatory effects of total saponins extracted from cultured wild ginseng roots (TSWG) on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. An elevated production of nitric oxide (NO) was detected in the RAW 264.7 cells in response to stimulation with LPS, as shown by NO detection assay using Griess reagent. However, pretreatment with TSWG inhibited the production of NO through the suppression of inducible NO synthase gene expression. Furthermore, the LPS-induced gene expression and production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) were significantly reduced by treatment with TSWG, as shown by ELISA, and western blot analysis and RT-PCR, respectively. In the LPS-stimulated RAW 264.7 cells, nuclear factor-kappa B (NF-kappa B) was translocated from the cytosol to the nucleus, while pre-treatment with TSWG induced the sequestration of NF-kappa B in the cytosol through the inhibition of the inhibitor of kappa B degradation, as shown by immunofluorescence staining. TSWG also contributed to the down-regulation of mitogen-activated protein kinases and Akt in the LPS-stimulated RAW 264.7 cells. Additionally, in the TSWG-treated RAW 264.7 cells, we observed the activation of nuclear factor (erythroid-derived 2)-like 2 and an increase in heme oxygenase-1 expression; these effects were associated with the inhibition of the generation of reactive oxygen species. The results from the present study indicate that TSWG exerts anti-inflammatory and antioxidant effects, suggesting that TSWG may be an effective therapeutic agent for inflammatory diseases and prevent cellular damage induced by oxidative stress.</P>

납, 수은 및 유기용제 폭로근로자들의 조기 신장 손상 지표인 요중 N-Acetyl-β-Glucosaminidase activity에 관한 조사연구

차철환,김광종,이은일 大韓産業醫學會 1993 대한직업환경의학회지 Vol.5 No.1

The urinary N-Acetyl-β-Glucosaminidase activity test has been recommended as sensitive method to detect early renal dysfunction by many toxic chemicals. To catch the high reference value of urinary N-Acetyl-β-Glucosaminidase activity in Korean, the total of 108 reference workers exposed only to noise were surveyed. And N-Acetyl-β-Glucosaminidase activities in 42 mercury workers at a fluorescent lamp manufacturing factory and 50 reference workers were measured to detect early renal dysfunction of mercury workers. The total of 27 mercury workers were followed 1 year to examine change of the N-Acetyl-β-Glucosaminidase activities according to the change of urinary mercury level. It was also examined to the N-Acetyl-β-Glucosaminidase activities of 8 lead exposed workers and 44 carbon disulfide exposed workers. It was examined to the correlation coefficients between the N-Acetyl-β-Glucosaminidase activities and total protein, β-1-microglobulin, β-2-microglobulin in 24 hour urine in 42 carbon disulfide exposed workers and 14 medical students as refernce group. And the correlation coeffecients between the N-Acetyl-β-Glucosaminidase activities in 24 hour urines and in spot urines were measured in 12 lead exposed workers and 43 mercury exposed workers. The results were as follows; 1. The high reference value of urinary N-Acetyl-β-Glucosaminidase activities in Korean was 180 nanomole methylumbellyferon/mg creatine of urine. 2. The correlation coefficients of N-Acetyl-β-Glucosaminidase activities and microalbumin, α-1-microglobulin, β-2-microglobulin in 24 hour urine were about 0.5 respectively. 3. The values of N-Acetyl-β-Glucosaminidase activities of spot urines in mercury exposed workers were statistically significant higher than those in reference group. and about 76.5% of workers of whom the urinary mercury level decreased after 1 year follow-up, also decreased the values of N-Acetyl-β-Glucosaminudase activities of spot urines. 4. There was no significant correlation between the N-Acetyl-β-Glucosaminidase activity of spot urines and blood lead level in lead exposed workers. But a half of workers have increased N-Acetyl-β-Glucosaminidase activities above the reference level. 5. The values of N-Acetyl-β-Glucosaminidase activities of spot urines in carbon disulfide exposed workers were statistically significantly higher than those in reference group. And for workers exposed to carbon disulfide and having retinopathy, the meanvalues of the N-Acetyl-β-Glucosaminidase activities were significantly higher, as compared to those having normal retina. 6. the correlation coefficients of N-Acetyl-β-Glucosaminidase activities between the values of 24 hour urines and those of spot urine were 0.76 in carbon disulfide exposed workers, 0.5 in lead exposed workers, 0.4 in mercury exposed workers, respectively. Among the correlation coefficients between the values of first morning urine samples and those of 24 hour urine samples were highest.

Electrospun nonwovens of shape-memory polyurethane block copolymers

Cha, Dong Il,Kim, Hak Yong,Lee, Keun Hyung,Jung, Yong Chae,Cho, Jae Whan,Chun, Byung Chul Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of applied polymer science Vol.96 No.2

<P>Synthesized shape-memory polyurethane (PU) block copolymers were used to prepare electrospun nonwovens via electrospinning. PU solutions were prepared with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran. The electrospun PU nonwovens were prepared with hard-segment concentrations of 40 and 50 wt %. The morphology of the electrospun fibers was investigated with scanning electron microscopy. The average diameter of low-viscosity (ca. 130–180 cPs) electrospun fibers was about 800 nm, and the morphology of the electrospun nonwovens was beaded-on fibers. In contrast, the average diameter of high-viscosity (ca. 530–570 cPs) electrospun fibers was about 1300 nm. In an investigation of the mechanical properties of the electrospun PU nonwovens, it was found that the tensile strength increased as the hard-segment concentration increased within a similar range of viscosities. Also, the tensile strength of the electrospun PU nonwovens in the machine direction was higher than that in the transverse direction because of a difference in the velocities of the drum collectors. The electrospun PU nonwovens with hard-segment concentrations of 40 and 50 wt % were found to have a shape recovery of more than 80%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 460–465, 2005</P>

A Study on Recovery from Potentially Lethal Damage Induced by γ-Irradiation in Plateau-phase vero Cells in vitro

Il Han Kim(김일한),Eun Kyung Choi(최은경),Sung Whan Ha(하성환),Charn Il Park(박찬일),Chang Yong Cha(차창룡) 대한방사선종양학회 1988 Radiation Oncology Journal Vol.6 No.1

방사선 조사후 발생한 잠재치사손상의 회복(PLDR)에 있어 조사선량 및 시간에 따른 환경변화가 회복의 동적양상에 미치는 영향을 Vero 세포계를 이용하여 실험하였다. 배양액을 교환시키지 않고 배양하여 평형기에 도달한 세포에 동물실험용 세시움 조사기로 1Gy~9Gy의 감마선을 조사하고 각 조사조건에서 0~6 및 24 시간동안 정치지킨 후 Agarose가 포함된 새로운 배양액에서 배양하였다. 16Gy를 조사한 동종의 세포를 feeder 세포로 첨가하여 배양액내의 전체세포수를 일정하게 한 조건에서 형성된 세포집락수에 따라 세포의 생존을 정하였다. 잠재치사손상의 회복은 2~4시간 정치후에 포화수준에 도달한 빠른 회복이었다. 방사선량이 증가함에 따라 회복속도는 증가하였고, 포화수준의 회복량도 증가하였다. Linear-quadratic model에 의한 ‘방사선량-생존분획’ 분석결과 잠채치사손상이 회복됨에 따라 일차 비활성계수 α는 급속히 감소하여 0에 접근하였고 이차 비활성계수 ß는 미미하게 증가하여 PLDR은 α로 표시되는 손상에 주로 영향을 주었다. Multitarget model에 따라 분석한 결과 Do는 변화가 없고 Dq가 증가하였다. 세포 생존분획이 높은 3 Gy 이하의 저선량 영역에서 dose modifying factor가 높아 잠재치사손상의 회복에 의한 영향이 저선량 영역에서 상대적으로 크게 나타났다. Recovery from potentially lethal damage (PLDR) after irradiation was studied in plateau-phase culture of Vero cells in vitro. Unfed plateau-phase cells were irradiated wth dose of 1 to 9 Gy using Cs-137 irradiator. Cells then were incubated again and left in situ for 0,1,2,3,4,5,6, and 24 hours and then were trypsinized, explanted, and subcultured in fresh RPMI-1640 media containing 0.33% agar. Cell survival was measured by colony forming ability. An adequate number of heavily irradiated Vero cells were added as feeder cells to make the total cell number constant in every culture dish. As the postirradiation in situ incubation time increased, surviving fraction increased by PLDR. The rate of PLDR was so rapid that increased surviving fraction reached saturation level at 2 to 4 hours after in situ incubation. As the radiation dose increased, the rate of PLDR fastened and the magnitude of increased surviving fraction at saturation level by PLDR also increased. In analysis of cell survival curve fitted to the linear-quadratic model, the linear inactivation coefficient (α) decreased largely and reached nearly to zero but the quadratic inactivation coefficient (ß) increased minimally by increment of postirradiation in situ incubation time. So PLDR mainly affected the damage expressed as α. In the multitarget model, significant change was not obtained in Do but in Dq Therefore, shoulder region in cell survival curve was mainly affected by PLDR and terminal slope was not influenced at all. And dose-modifying factor by PLDR was relatively higher in shoulder region, that is, in low dose area below 3 Gy.

단일벽 음향전달손실 이론치에 관한 고찰

차일환 연세대학교 산업기술연구소 1978 논문집 Vol.8 No.1

The sound transimission loss of the single wall is mainly determined by its area density. Theoretically the determination of the sound transmission loss depends on the Mass law. There are several kinds of the theoretical eqations which are concerned with sound transmission loss. The result of computation from the six equations which are related with sound transmission loss. Fifty seven area densities are used for the computation of the sound transmission loss. Three equations of the mean sound transmission loss are applied to the fifteen area density to get the mean value of the sound transmission losses. As a results to get the sound transmission loss the equation that is applied should differ in accordance with the area density.