• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.1
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• pp.9-23
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• 1997

A numerical study of a two-layer, stratified flow is investigated, using the implicit finite difference method in one dimension. The results of computational method have been tested and, in case of lock exchange flow, compared with the results of experimental data. The results of model experiments with various interfacial, bottom friction coefficients along with various time weighting factor of numerical scheme and dissipative interface are shown and discussed. Two-layer model experiment has been also carried out to investigate the generation and propagation characteristics of internal tidal wave over the steep bottom topography under stratified condition. The internal wave seems to well radiate through the downstream boundary under the experiments adopting radiation conditions both at two layers and only at upper layer, confirming the applicability of radiational boundary condition in stratified flows. It is also shown that the internal wave through the downstream boundary propagates more actively with increasing thickness of lower layer in the downstream. This implies that the potential tidal energy in the interface will depend upon the thickness of lower layer for the constant thickness of upper layer.

• Korean Journal of Environmental Biology
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• v.17 no.2
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• pp.191-198
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• 1999

Enzyme-aided bleaching of softwood and hardwood kraft pulps by a xylanase preparation from an alkalophilic fungus Cephalospotium sp. RYM-202 was studied. Maximal solubilization of Pulp xylan was obtained at 5$0^{\circ}C$ in both kraft pulps. The optimum pH of the enzyme for the hydrolysis of pulp xylan was 8.0 and more than 90% of the maximal activity was detected at 9.0. The positive effects of xylanase pretreatment on bleachability of softwood and hardwood kraft pulps were observed. The kappa number of softwood and hardwood kraft pulps was decreased by 3.7 and 2.0 units, respectively. The pulp fibre integrity was not significantly affected by xylanase pretreatment when the physical properties of handsheets made from xylanase-treated pulps were compared with those of handsheets from untreated pulps. These results indicate that the alkaline xylanase of Cephalospotium sp. RYM-202 is well suitable for application in enzymatic prebleaching of softwood and hardwood kraft pulps under the alkaline conditions.

• The Journal of Engineering Geology
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• v.17 no.3
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• pp.419-424
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• 2007

The contents were investigated by the monitoring survey from the soils and tailings caused by numerous abandoned mines in Korea. Cause heavy metals due to abandoned metal mines are raising significant environmental problems. But it is an important key such as a leaching and a transfer mechanism to evaluate contamination levels caused by abandoned mines. In this study the column test was carried in order to calculate a leaching level from soils and tailings. It was demonstrated that the leaching of Pb, Cd and Mn was expressed with similar behaviors and that of As and Cu was expressed with similar behaviors. For Zn, the leaching behavior was shown a serious leaching level with 40 mg/kg during the 45days. This was explained by Zn high contents of soils Zn in a natural world and ORP conditions where the leaching of Zn was occurred easily. Hence it was necessary that the survey of ORP was a key as well as total contents for the management of abandoned metal mines. We could estimate the chemical forms of heavy metals using the physical index such as ORP and pH and reduce the risk from heavy metals caused by abandoned metal mines.

• Science of Emotion and Sensibility
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• v.14 no.1
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• pp.1-6
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• 2011

A perceptual reaction to human being's gaits has "regularity" that possibly obtains sympathy among people. This thesis is in the vein of the study that performs the research on the quantificational extraction of the regularity, reconstitute the result, and apply it to controlling behavior. The purpose of this thesis lies in assuring the validity of the future research by demonstrating the following hypothesis: when the physical numerical values of the gait "A" whose perceptual reaction is "a" and those of the gait "B" whose perceptual reaction is "b" are arbitrarily blended, the perceptual reaction to this blended gait also corresponds to the blend of "a" and "b", "a/b". I blended the samples of two types of gaits in the form of Bipeds using the EAM made by 3D Studio Max Script. Blending outcomes were obtained successfully for four times out of the six tries in total. It implies that without utilizing other methods such as Motion Capturing, the basic Bipeds data itself has an enough capability to generate various gaits of Bipeds. Although the present research targets only the Bipeds samples equipped with the 1Cycle moving condition of arms and legs, I acknowledge that a tool that makes blending possible under various moving conditions is necessary for a completed system.

• Science of Emotion and Sensibility
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• v.21 no.1
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• pp.83-90
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• 2018

The purpose of this study is for fundamental research of meditation smart wear for physical and mental healing, and researching method for monitoring phase of meditation through textile by measuring the number of abdominal respiration when meditating. For this purpose, the research implemented Single Wall Carbon Nano-Tube (SWCNT) based strain gauges type textile sensor, considered reliability and validity of respiratory sensing, and analyzed efficiency of respiratory sensing based on body parts comparatively. The first preliminary experiment was to evaluate the performance of textile sensor through abdominal model dummy which open and shut of 5 cm repeatedly for 2 minutes at the rate of 0.1Hz in order to simulate abdominal respiration. It concluded signal efficiency between reference sensor(BIOPAC) and textile respiratory sensor appears statistically significant (p<0.001). The second experiment were conducted with 4 subjects doing abdominal respiration under same conditions, and after comparing the signal values between two sensors from 4 attached locations(around center and sides of omphali and phren), center of omphali and sides of phren were selected as suitable location for measuring meditational breathing as they showed large and stable signals. In result, this research aimed for implementing of the textile sensor for sensing meditational breathing of long respiration cycle, review of reliability and validity for sensing number of meditational respiration with the sensor and consideration of sensing efficiency by sensing location on body parts.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.1-7
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• 2017

Polydimethylsiloxane (PDMS) can be deposited on various substrates using chemical vapor deposition process, which results in the formation of PDMS thin films with thickness below 5 nm. PDMS layers can be evenly deposited on surfaces of nanoparticles composed of various chemical compositions such as $SiO_2$, $TiO_2$, ZnO, C, Ni, and NiO, and the PDMS-coated surface becomes completely hydrophobic. These hydrophobic layers are highly resistant towards degradation under acidic and basic environments and UV-exposures. Nanoparticles coated with PDMS can be used in various environmental applications: hydrophobic silica nanoparticles can selectively interact with oil from oil/water mixture, suppressing fast diffusion of spill-oil on water and allowing more facile physical separation of spill-oil from the water. Upon heat-treatments of PDMS-coated $TiO_2$ under vacuum conditions, $TiO_2$ surface becomes completely hydrophilic, accompanying formation oxygen vacancies responsible for visible-light absorption. The post-annealed $PDMS-TiO_2$ shows enhanced photocatalytic activity with respect to the bare $TiO_2$ for decomposition of organic dyes in water under visible light illumination. We show that the simple PDMS-coating process presented here can be useful in a variety of field of environmental science and technology.

• Journal of Life Science
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• v.27 no.5
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• pp.591-599
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• 2017

It is well established that endurance performance is negatively affected by environmental heat stress. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling and per-cooling for endurance athletes. Some cooling strategies are more logistically challenging than others, and thus are often impractical for use in training or competition. The purpose of this study was to review the literature on the use of cooling interventions in the improvement of performance and recovery from exercise-induced heat stress. We undertook an examination that focused on the effects of pre-cooling and per-cooling on the improvement in endurance performance and the effects of post-exercise cooling on recovery. The benefits for pre-cooling and per-cooling strategies undertaken in the laboratory setting could be employed by athletes who compete in hot environmental conditions to improve performance. Most laboratory studies have shown improvements in endurance performance following pre-cooling and per-cooling, and in recovery following post-cooling. Cooling strategies such as cooling vest, neck cooling collar, menthol and ice slurry are practically relevant to sports field. Cooling interventions that can be applied frequently to reduce thermal strain prior to, during and directly after training appear to be the best effective strategy to improve performance and recovery. Future research is warranted to investigate the effectiveness of practical pre-cooling and per-cooling strategies in competition or field settings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.150-159
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• 2011

The need of securing the stability and extending service lives by efficient maintenance of deteriorated tunnels for several decades has been increased. The stability and the usability of conventional tunnels can be decreased by change of physical properties of the surrounding ground, geometrical properties of the tunnel, an underground water level, environmental conditions, oxidation of lining and the breakdown of constituent materials. In respect of a long-term view, it is need to check all sorts of degradation, the degree of damage and durability to improve the serviceability and to come up with measures to maintain effectively. This paper is about study to analyze the stability of conventional tunnels(American Steel Support Method. ASSM). Three tunnels are chosen in those built in the 1930s and 1960s and the locations of tunnels are selected variously(ChungCheong, GyungBuk, GangWon, Jeolla, etc.) to secure reliability of this study. The state of repair and reinforcement of linings, cracks, and thickness and strength of lining of conventional tunnels in service are researched, compared and analyzed. The crack gauge, the GPR, the schmitt hammer was used for the crack investigation, cavitation, the strength respectively. By using these, the comparative analysis for conventional tunnels was conducted. As a result, there are more cracks in tunnels built in the 1930s than those of tunnels built in the 1960s, and lining strength of the 1930s is higher than those of the 1960s. The thickness of lining in tunnels built in the 1960s is higher than those in tunnels built in the 1930s. In proportion to thickness, cavitation occurred more frequently in tunnels built in the 1960s compared to those in tunnels built in the 1930s.

• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.333-342
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• 2006

The cdma2000 lxEV - DO mobile communication system provides broadcast and multicast services (BCMCS) to meet an increasing demand from multimedia data services. The servicing of video streams over a BCMCS network must, however, face a challenge from the unreliable and error-prone nature of the radio channel. The BCMCS network uses Reed-Solomon coding integrated with the MAC protocol for error recovery. We analyze this coding technique and show that it is not effective in the case of slowly moving mobiles. To improve the playback quality of an MPEG-4 FGS video stream, we propose the Hybrid error recovery scheme, which combines Reed-Solomon with ARQ, using slots which are saved by reducing the Reed-Solomon coding overhead. The target packets to be retransmitted are prioritized by a utility function to reduce the packet error rate in the application layer within a fixed retransmission budget. This is achieved by considering of the map of the error control block at each mobile node. The proposed Hybrid error recovery scheme also uses the characteristics of MPEG-4 FGS (fine granularity scalability) to improve the video quality even when conditions are adverse: slow-moving nodes and a high error rate in the physical channel.

• Journal of The Korean Association For Science Education
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• v.25 no.2
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• pp.184-196
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• 2005

The purpose of this study is to identify various issues contributing to the current issues of students not wanting to major in science and engineering. and further explore various strategies to encourage their higher education in the science and engineering area. The study administered survey on students' perception towards the science related profession including respondents' gender, grade, their attitude towards woman scientists, perception on the woman scientists, scientists as profession, their level of knowledge on the scientists, and if there is any they respect. The results indicated that overall perceptions on the scientists as career for high school students was positive, but there was more negative acceptance for the juniors since they are more concerned with their majors at the university: higher for students who are in the natural science area than the ones in the social science school since they are more directly related than others. The perception on the woman scientists and girls in the science and engineering majors was positive. However, there were some differences in the response level among the items. Among these, considering the job availability and conditions, the perception was more negative than the others. Also the result indicated that both boys and girls disagree that the science-related profession may be gender-inappropriate for girls due to physical and cognitive characteristics. Results also indicated the level of awareness among scientists, they had higher awareness for male scientists than that of the female, and also international ones than the national ones. And many girls did not have positive image of a successful woman scientists.