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Sound Absorption Rate and Sound Transmission Loss of Wood Bark Particle (목재수피 파티클의 흡음율과 음향투과손실)
( Chun-Won Kang ),( Eun-Suk Jang ),( Sang-Sik Jang ),( Ho-Yang Kang ),( Seog-Goo Kang ),( Se-Chang Oh ) 한국목재공학회 2019 목재공학 Vol.47 No.4
In this study, sound absorption capability and sound transmission loss of several kinds of target densities and thickness for six species of wood bark particle were estimated by the transfer function and transfer matrix methods. Resultantly, the mean sound absorption coefficient of a 100-mm thick Hinoki wood bark particle mat was 0.90 in the frequency range of 100-6400 Hz, whereas the mean sound absorption rate of a 50-mm thick Hinoki wood bark particle mat was 0.84 in the same frequency range. Particularly, at a thickness of 100 mm, it reached almost up to 100% in the frequency range of 1 KHz. The sound transmission losses of 100-mm thick Hinoki wood bark particle mat with a target density of 0.16 at 500 and 1000 Hz were 15.30 and 15.73 dB, respectively. When a 10-mm thick plywood was attached to the back of the wood particle mat, the sound transmission losses was increased by 20-30 dB. Wood bark can be used as an acoustical material owing to its high sound absorption rate and transmission loss.
Removal of Aerosol Through Fibrous Filter as a Function of Particle Size and Velocity
Sang Hoon Lee,Kwan Sik Chun,Hoo Keun Lee Korean Nuclear Society 1984 Nuclear Engineering and Technology Vol.16 No.1
유리섬유 여과포에 의한 0.1~0.45$\mu\textrm{m}$ 크기의 DOP 부유입자의 제거효율시험을 1~10cm/sec의 유속범위에서 수행하였다. 섬유여과포에 의한 미세입자의 여과는 여과속도에 의하여 결정되는데, 최소제거 효율을 나타내는 DOP 입자의 크기는 여과속도가 증가함에 따라 감소한다. Kuwabara Cell Model과 Von Mises Transformation을 사용하여 유리섬유 여과포내에서 화산에 의한 입자 제거효율을 수치해석적으로 전개하여 구하였으며, 이 계산치는 실험치와 잘 일치하였다. 본 실험의 결과는 여과포의 입자제거효율을 예측하고 최적 운전조건을 추구하는데 기여할 수 있을 것이다. Filtration efficiency tests were conducted on a fiberglass mat filter with DOP aerosol having a diameter from 0.l${\mu}{\textrm}{m}$ to 0.45${\mu}{\textrm}{m}$ in the face velocity range of 1cm/sec to 10cm/sec. Filtration of submicron particles by a fibrous filter is characterized by a face velocity. The size of DOP aerosol which has a minimum removal efficiency decreases with increasing the velocity. A numerical solution of the diffusion equation is obtained for a fiberglass mat filter by using "Kuwabara's cell model" for the flow field and Von Mises Transformation for the actual flow around a fiberglass. The present theoretical results agree quite well with the experimentals for fiberglass mat. This result could be contributed to predict the removal efficiency on an air filter and to optimize the operating condition of an air purification system with a filter. a filter.
Genetic Diversity and Population Structure of Kalopanax pictus (Araliaceae)
( Sang Duk Jung ),( Hong Wook Huh ),( Jung Hee Hong ),( Joo Soo Choi ),( Hyun Sik Chun ),( Kyoug Hwan Bang ),( Man Kyu Huh ) 한국식물학회 2003 Journal of Plant Biology Vol.46 No.4
Kalopanax pictus (Araliaceae) is a long-lived woody species primarily distributed throughout East Asia. This species is regarded as medically and ecologically important in Korea. We used starch gel electrophoresis to investigate its allozyme variation and genetic structure in samples from Korean populations (both natural and cultivated). Our analysis of 10 enzymes revealed 18 loci, of which 10 were polymorphic (55.6%). Genetic diversity at the species and population levels were 0.200 and 0.149, respectively, with the mean for cultivated populations (0.124) being lower than for natural (wild) populations (0.181). Asexual and sexual reproduction modes, perennial habitat, and longevity all were possible factors contributing to such high diversity. An indirect estimate of the number of migrants per generation (N_(m)=1.08) indicated that gene flow was not extensive among these Korean populations. Therefore, we suggest that geographical distance as well as reproductive isolation between wild and cultivated plants may play roles in shaping the population structure of this species.
( Sung Won Youn ),( Young Soo Kim ),( Myung Chun Lee ),( Dong Sik Chung ) 한국스포츠정책과학원(구 한국스포츠개발원) 2001 International Journal of Applied Sports Sciences Vol.13 No.1
The purpose of this research is to investigate the effectiveness of far infrared rays on the human body in enhancing athletic performance. The test was conducted in an environment similar to the body temperature of 37℃. Emission rate of 0.911 and emission energy of 3.51 × 102 W/m2 · ㎛ from the infrared rays released from 100% cotton material processed in plant distillation was incorporated into the sportswear. The subjects who participated in the research were soccer players at S University in Seoul. They were separated into two groups of ten by random allocation: the Experimental Group (EG) and the Control Group (CG). In order to test the effectiveness of wearing the functional sportswear, differences in aerobic capacity and recovery from fatigue were measured These were observed through changes of maximum oxygen consumption, anaerobic threshold level, exercise performance time, and lactic acid concentration in the Blood. The number of red blood cells and cell fidelity levels were used in analyzing the changes in the blood As a result of the research, the far infrared ray emitting functional sportswear demonstrated increase in maximum oxygen consumption by 3.5%, anaerobic threshold by 3.2%, and total exercise performance time by 3.6%. Also, progressive changes in the number of red blood cells and cell fidelity levels in carrying oxygen proved to contribute to enhancing aerobic exercise capacity. Thus, it is proven to be highly effective as an ergogenic aid.
( Sang Hoon Park ),( Hoon Jai Chun ),( Yong Dae Kwon ),( Bo Ra Keum ),( Yeon Seok Seo ),( Yong Sik Kim ),( Yoon Tae Jeen ),( Soon Ho Um ),( Chang Duck Kim ),( Ho Sang Ryu ),( Ji Hye Lee ),( Yang Seok 대한소화기학회 2008 Gut and Liver Vol.2 No.3
Background/Aims: Endoscopic mucosal resection can cure early gastric cancer. The risk of lymphatic metastasis is related to the depth of submucosal invasion by the mucosal malignancy, with a resection depth of 500 μm generally accepted as a safe cut-off. However, excessive thinning induced by stretching of the resected tissue sometimes preventing a precise diagnosis. We studied the effects of stretching on different layers and sites of gastric tissue. Methods: Porcine stomachs were cut into 2.0×2.0 cm pieces, and pieces from body were stretched to 2.5, 3.0, and 3.5 cm. Pieces from the cardia, body, and antrum were also stretched to 3.0 cm. The thickness of each layer was measured and analyzed statistically. Results: Whole gastric wall and submucosal layers showed gradual thinning, with stretching to 3.5 cm tearing the tissues and resulting in imperfect extension. The submucosa was thinner in body tissue than in cardia and antrum tissues. Stretching to 3.0 cm induced a consistent decrease in submucosal thickness (30-70%). The change in thickness varied widely between individual samples. Conclusions: A resection margin of 500μm might be insufficient for the complete removal of malignancy. Moreover, the thickness of the submucosal layer differs with the gastric site and between individuals. Future studies are needed to confirm the findings in human tissue. (Gut and Liver 2008;2:199-204)
Spermatotoxic effects of α-chlorohydrin in rats
Sung-Hwan Kim,In-Chul Lee,Jeong-Hyeon Lim,Changjong Moon,Chun-Sik Bae,Sung-Ho Kim,Dong-Ho Shin,Hyoung-Chin Kim,Jong-Choon Kim 한국실험동물학회 2012 Laboratory Animal Research Vol.28 No.1
This study was conducted to investigate the potential effects of α-chlorohydrin (ACH) on epididymal function and antioxidant system in male rats. The test chemical was administered to male rats by gavage at doses of 0, 3, 10, and 30 mg/kg/day for 7 days. Twenty-four male rats were randomly assigned to four experimental groups, with six rats in each group. Spermatotoxicity was assessed by measurement of reproductive organ weight, testicular sperm head count, epididymal sperm motility and morphology, histopathologic examination, and oxidative damage analysis in rats. At 30 mg/kg/day, an increase in the incidence of clinical signs, epididymis weight, and gross necropsy findings of the epididymis, a decrease in the sperm motility, and an increased incidence of histopathological changes of the epididymis were observed in a dose-dependent manner. At 10 mg/kg/day, an increased incidence of clinical signs and histopathological changes and decreased sperm motility were observed. In the oxidative damage analysis, an increase in the malondialdehyde concentration and a decrease in the glutathione content and glutathione peroxidase and catalase activities in the epididymal tissue were detected at ≥3 mg/kg/day. The results show that graded doses of ACH elicit depletion of the antioxidant defense system and that the spermatotoxicity of ACH may be due to the induction of oxidative stress.
Role of Ca<SUP>2</SUP> in the Stimulation of Glucose Transport by Insulin in Adipocytes
Sung-Hoe Chang,Yeon Jin Jang,Kun-Koo Park,Ghi Su Kim,Hee Jeong Ryu,Chun Sik Park 대한생리학회-대한약리학회 1999 The Korean Journal of Physiology & Pharmacology Vol.3 No.3
<P> We investigated the role of Ca<SUP>2</SUP> and protein kinases/phosphatases in the stimulatory effect of insulin on glucose transport. In isolated rat adipocytes, the simple omission of CaCl<SUB>2</SUB> from the incubation medium significantly reduced, but did not abolish, insulin-stimulated 2-deoxy glucose (2-DG) uptake. Pre-loading adipocytes with intracellular Ca<SUP>2</SUP> chelator, 5,5 -dimethyl bis (<I>o</I>-aminophenoxy)ethane-N,N,N N tetraacetic acetoxymethyl ester (5,5 -dimethyl BAPTA/AM) completely blocked the stimulation. Insulin raised intracellular Ca<SUP>2</SUP> concentration ([Ca<SUP>2</SUP>]<I><SUB>i</SUB></I>) about 1.7 times the basal level of 72⁑5 nM, and 5,5 -dimethyl BAPTA/AM kept it constant at the basal level. This correlation between insulin-induced increases in 2-DG uptake and [Ca<SUP>2</SUP>]<I><SUB>i</SUB></I> indicates that the elevation of [Ca<SUP>2</SUP>]<I><SUB>i</SUB></I> may be prerequisite for the stimulation of glucose transport. Studies with inhibitors (ML-9, KN-62, cyclosporin A) of Ca<SUP>2</SUP>-calmodulin dependent protein kinases/phosphatases also indicate an involvement of intracellular Ca<SUP>2</SUP>. Additional studies with okadaic acid and calyculin A, protein phosphatase-1 (PP-1) and 2A (PP-2A) inhibitors, indicate an involvement of PP-1 in insulin action on 2-DG uptake. These results indicate an involvement of Ca<SUP>2</SUP>-dependent signaling pathway in insulin action on glucose transport.