• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.145-152
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• 2010

This study evaluated the fatigue degradation in a SUS316L specimen using the nonlinear ultrasonic method. The nonlinearity of the ultrasonic wave was estimated by a relative nonlinear parameter defined as the ratio of the amplitudes for the fundamental wave to the second harmonic wave. In the experiment, a measurement system with contact transducers was constructed; reliable measurements were assured by keeping measurement conditions consistent and reducing extra harmonics generated in the measurement system. Two types of SUS316L specimen were used in experiments; a rotating bar fatigue specimen and a tensile fatigue specimen. The fatigue condition used was high cycle fatigue. The former specimen had a cylindrical shape and was used to observe the change in the nonlinear parameter after fatigue accumulation in a specimen. The latter was a plate-shaped specimen and was used to confirm the change in the nonlinear parameter at the position where the fatigue stress was concentrated. The measured nonlinear parameter showed a strong correlation to the damage level in both fatigue tests.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.06a
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• pp.91-120
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• 1996

경제발전과 더불어 산업의 많은 분야에서 순수 및 초순순의 사용이 증가하고 있으나, 환경오염에 의한 원수의 오염에 따라 순수 및 초순순제조의 장치비와 처리비용의 증가가 야기되고 있다. 현재 국내에는 화력, 원자력발전소를 비롯하여 열병합발전소, 석유화학공장, 제약회사, 전기 전자부품회사, 반도체회사 및 철강회사 등 많은 분야에서 순수 및 초순수 제조장치의 구성과 성능이 많은 차이를 나타내고 있다. 국내의 초순수 제조장치는 90% 이상이 이온교환수지를 사용하는 이온교환법과 UF, R/O System과 같은 Membrane을 사용하는 Membrane System을 병행하여 적용하고 있다. 국내 초순수처리 Plant에서는 통상 전처리 System과 1차 순수제조 System 및 초순수 System이 상호 연결되어 Plant가 구성 운영되고 있다. 전처리 System에는 응집침전, 여과 흡착, 살균 등이 적용되고 있으며 여과 System에 Membrane을 적용할 수 있으나 국내에서는 특별한 경우를 제외하고 대부분 전처리 여과 System에 Media Filter를 사용한다. 전처리 System도 순수처리 장치의 전처리로는 없어서는 안되는 System이지만 여기에는 전처리 System을 제외하고 국내에서 적용하고 있는 초순수처리 System의 공정현황과 각 System별 특징을 설명하고 있다. 초순순 System에는 요구 수질에 따라 다소 차이가 있지만 반도체 공업에서 사용되는 초순수 System이 이중 최고의 Grade로 반도체공업에서 적용되고 있는 System을 기준하였다. 특히 Membrane을 적용한 초순수제조 System이 증가하고 있어 R/O, ED, EDR, CDI, (EDI)와 같은 Membrane System의 특성과 원리를 검토하였다.대적으로 높은 산소확산계수와 물에 대해서는 낮은 투과도를 가져야 한다. 높은 산소확산계수는 반응을 빠르게 하는 잇점이 있으며 물에 대한 낮은 투과도는 센서내의 전해질 물질을 유지보호하는 역할을 한다. 분리막이 산소전극에 이용될 경우 높은 산소 확산계수 이외에도 적절한 기계적 강도, 열적 안정성 등이 요구된다. 몰입이 가능하여 임계치가 저하된 것으로 여겨진다. 또한 광학적 이득의 존재는 이 구조에 의한 극단파장 반도체 레이저다이오드의 실현 가능성을 나타내는 것이다.548 mL에 비해 통계학적으로 의의 있게 적었다(p<0.05). 결론: 관상동맥우회로 조성수술에서 전방온혈심정지액을 사용할 때 희석되지 많은 고농도 포타슘은 fliud overload와 수혈을 피하고 delivery kit를 사용하지 않음으로써 효과적이고 만족할 만한 심근보호 효과를 보였다.를 보였다.4주까지에서는 비교적 폐포는 정상적 구조를 유지하면서 부분적으로 소폐동맥 중막의 비후와 간질에 호산구 침윤의 소견이 특징적으로 관찰되었다. 결론: 분리 폐 관류는 정맥주입 방법에 비해 고농도의 cisplatin 투여로 인한 다른 장기에서의 농도 증가 없이 폐 조직에 약 50배 정도의 고농도 cisplatin을 투여할 수 있었으며, 또한 분리 폐 관류 시 cisplatin에 의한 직접적 폐 독성은 발견되지 않았다이 낮았으나 통계학적 의의는 없었다[10.0%(4/40) : 8.2%(20/244), p>0.05]. 결론: 비디오흉강경술에서 재발을 낮추기 위해 수술시 폐야 전체를 관찰하여 존재하는 폐기포를 놓치지 않는 것이 중요하며, 폐기포를 확인하지 못한 경우와 이차성 자연기흉에 대해서는 흉막유착술에 더 세심한 주의가 필요하다는 것을 확인하였다. 비디오흉강경수술은 통증이 적고, 입원기간이 짧고, 사회

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.3
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• pp.351-355
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• 2005

This study was performed to investigate the influences of resistant starch (HM: HI-MAIZE) and HM-D (HI-MAIZE DIET) fortified with D-factor (consisted of Psyliium husk, polydextrose and hydrocitric acid) on the glucose and bile acid absorption and production of short chain fatty acids (SCFA). HM-D absorbed more glucose and bile acid than did HM. The glucose transport of HM and HM-D against dialysis membrane showed 77% and 68% for 4h, respectively. After 24h, bile acid transport of HM and HM -D showed 65% and 62.3%, respectively. The HM and HM-D produced 217.8 mM and 264.0mM of SCFA, respectively. The production of butyric acid in HM-D (32.7mM) showed higher than that of HM (26.9mM). The addition of D-factor to HM increased the physiological function of dietary fiber through the glucose and bile acid absorption and production of SCFA.

• Korean Journal of Cognitive Science
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• v.17 no.2
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• pp.75-102
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• 2006

Three experiments were conducted using a verification task to examine good and poor readers' generation of causal inferences(with because sentences) and contrastive inferences(with although sentences). The unfamiliar, critical verification statement was either explicitly mentioned or was implied. In Experiment 1, both good and poor readers responded accurately to the critical statement, suggesting that both groups had the linguistic knowledge necessary to the required inferences. Differences were found, however, in the groups' verification latencies. Poor, but not good, readers responded faster to explicit than to implicit verification statements for both because and although sentences. In Experiment 2, poor readers were induced to generate causal inferences for the because experimental sentences by including fillers that were apparently counterfactual unless a causal inference was made. In Experiment 3, poor readers were induced to generate contrastive inferences for the although sentences by including fillers that could only be resolved by making a contrastive inference. Verification latencies for the critical statements showed that poor readers made causal inferences in Experiment 2 and contrastive inferences in Experiment 3 doting comprehension. These results were discussed in terms of context effect: Specific encoding operations performed on anomaly backgrounded in another passage would form part of the context that guides the ongoing activity in processing potentially relevant subsequent text.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.1
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• pp.27-35
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• 2013

Purpose: The present study was conducted to investigate the changes in the physical properties of RGP lenses induced by the polishing during the process of RGP lens manufacturing, and further evaluate the differences in the actual wearer's comfort and the tear film break-up time caused by these changes. Methods: RGP lenses (fluorosilicone acrylate material) were divided into 4 groups by the different lens-polishing time like 0, 25, 50 and 100 seconds and the thickness, the surface roughness and the wetting angle of those lenses were compared. Furthermore, the comfortability of the lens wear was surveyed after applying these lenses on the subject's eyes with normal tear volume and the non-invasive tear break-up time of the wearers was measured. Results: The central thickness of 4 RGP lenses made of different lens-polishing time was not significantly different however, the lens surface was changed smoother after polishing to be confirmed by scanning electron microscopy. The wetting angle of the RGP lens significantly decreased in accordance with the increase of polishing time. Thus, the difference of approximately $16^{\circ}$ between 0 second and 100 seconds-polishing was statistically significant. The actual wearing feeling of RGP lens was tended to improve in accordance with the increase of the lens wettability however, it was not proportional improvement. The non-invasive tear break-up time of the lens wearers showed different aspect compared with the changes in lens wettability and the actual feeling of RGP lens wear. Conclusions: In this study, better lens wettability, thinner lens thickness, and/or improved lens surface induced by physical stimuli in the process of RGP lens manufacturing was not well-correlated with the increase of actual subjective/objective satisfaction in RGP lens wear. Thus, the consideration of physical properties of the lens as well as the lens wearers' physiological factors in the process of RGP lens manufacturing may be suggested.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.215-224
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• 2013

We clarified the background for establishment of vegetation by comparing the spatial distribution maps of vegetation and substrate on a gravel bar in the Bangtae stream located on Inje-gun of Gangwon-do, the central eastern Korea. The total vegetation coverage was higher in the interior and lower in the marginal parts of the gravel bar. Spatial distribution of vegetation on the longitudinal section of the gravel bar tended to be arranged in the order of shrub, subtree, and tree dominated vegetation types from the front (upstream) toward the rear (downstream) parts. Coverage of the herbaceous plants was higher in the central and rear parts and lower in the front and right parts of the gravel bar. Vegetation height was higher in the rear part and became lowered as move toward the front part. Substrate was distributed in the order of boulder, gravel, sand, and boulder from the front toward the rear parts. Ordination of stands based on vegetation data was arranged in the order of annual plant, perennial herb, shrub, and tree dominated vegetation as move from the right to the left parts on the axis I. Species richness was higher in the order of Pinus densiflora community, Phragmites japonica community, Salix gracilistyla community, Fraxinus rhynchophylla community, annual plant dominated vegetation, and Prunus padus for. padus community based on the species rank-abundance curve. The order based on the Shannon's index was some different; diversity of Phragmites japonica community and Salix gracilistyla community, which showed higher dominance degree, were low differently from species richness. In conclusion, it was evaluated that the gravel bar newly established toward the upstream and vegetation dynamics of the gravel bar seemed to follow ecosystem mechanisms of succession. As were shown in the above results, the Bangtae stream corresponded to the upstream and thereby particle size of substrate was big. Therefore, they move by rolling and are accumulated for the upstream. Vegetation types were arranged in the order of woodland, shrub-land and grassland from the rear toward the front parts of the gravel bar and thereby reflected the formation process of the bar. However, the gravel bar is disturbed frequently by not only the running water but also the suspended sand as the dynamic space. Such disturbances cause habitat diversity and consequently led to high biodiversity.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.73-82
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• 1997

Regional myocardial blood flow (rMBF) can be noninvasively quantified using N-13 ammonia and dynamic positron emission tomography (PET). The quantitative accuracy of the rMBF values, however, is affected by the distortion of myocardial PET images caused by finite PET image resolution and cardiac motion. Although different methods have been developed to correct the distortion typically classified as partial volume effect and spillover, the methods are too complex to employ in a routine clinical environment. We have developed a refined method incorporating a geometric model of the volume representation of a region-of-interest (ROI) into the two-compartment N-13 ammonia model. In the refined model, partial volume effect and spillover are conveniently corrected by an additional parameter in the mathematical model. To examine the accuracy of this approach, studies were performed in 9 coronary artery disease patients. Dynamic transaxial images (16 frames) were acquired with a GE $Advance^{TM}$ PET scanner simultaneous with intravenous injection of 20 mCi N-13 ammonia. rMBF was examined at rest and during pharmacologically (dipyridamole) induced coronary hyperemia. Three sectorial myocardium (septum, anterior wall and lateral wall) and blood pool time-activity curves were generated using dynamic images from manually drawn ROIs. The accuracy of rMBF values estimated by the refined method was examined by comparing to the values estimated using the conventional two-compartment model without partial volume effect correction rMBF values obtained by the refined method linearly correlated with rMBF values obtained by the conventional method (108 myocardial segments, correlation coefficient (r)=0.88). Additionally, underestimated rMBF values by the conventional method due to partial volume effect were corrected by theoretically predicted amount in the refined method (slope(m)=1.57). Spillover fraction estimated by the two methods agreed well (r=1.00, m=0.98). In conclusion, accurate rMBF values can be efficiently quantified by the refined method incorporating myocardium geometric information into the two-compartment model using N-13 ammonia and PET.