• Journal of ILASS-Korea
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• v.11 no.1
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• pp.39-47
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• 2006

In-cylinder flows in a motored 3.5L four-valve SI engine were investigated quantitatively using three-component LDV system, to determine how engine configuration affects the flow field. The purpose of this work was to develop quantitative methods which correlate in-cylinder flows to engine performance. For this study, two distinct intake/piston arrangements were used to examine the flow characteristics. Quantification of the flow field was done by calculating two major parameters which are believed to characterize adequately in-cylinder motion. These quantities were turbulent kinetic energy(TKE) and tumble ratio in each plane at each crank angle. The results showed that in-cylinder flow pattern is dominated by the intake effects and two counter rotating vortices, developed during the intake stroke, produced relatively low tumble ratio. Therefore, the applicability of these quantities should be carefully considered when evaluating characteristics resulting from the complex in-cylinder flow motions.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 1995.03a
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• pp.46-46
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• 1995

We investigated the reliablity of the ultrasonography for diagnosis of rotatar cuff taers. We prepared histological sections of forty shoulder joints In match the ultrasound planes, and conducted a comparative study of tke two sets of images. hi cases of rotator cuff tear, hyperechogenic and cartilaginfication of the tear site were detected as hyperechogenic foci. On the countrary, the regions in which tendon fibers were decreased or absent showed sonolucent areas. We caluculated the echo level of rotator cuff objectively. The area of abnormal echo level and the other regions located in the same depth of the rotator cuff were defined by ultrasonic equipment. The mein difference in these two echo levels was calculated. The mean difference in patients with rotator cuff tears was larger than that in normal cases. These results indicate that ultrasonography is a useful procedure in many patients with rotator cuff lesions.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.23-60
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• 2016

The major objective of this study was to develop further understanding of 3D nearshore hydrodynamics under a variety of wave and tidal forcing conditions. The main tool used was a comprehensive 3D numerical model - combining the flow module of Delft3D with the WAVE solver of XBeach - of nearshore hydro- and morphodynamics that can simulate flow, sediment transport, and morphological evolution. Surf-swash zone hydrodynamics were modeled using the 3D Navier-Stokes equations, combined with various turbulence models (${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES). Sediment transport and resulting foreshore profile changes were approximated using different sediment transport relations that consider both bed- and suspended-load transport of non-cohesive sediments. The numerical set-up was tested against field data, with good agreement found. Different numerical experiments under a range of bed characteristics and incident wave and tidal conditions were run to test the model's capability to reproduce 3D flow, wave propagation, sediment transport and morphodynamics in the nearshore at the field scale. The results were interpreted according to existing understanding of surf and swash zone processes. Our numerical experiments confirm that the angle between the crest line of the approaching wave and the shoreline defines the direction and strength of the longshore current, while the longshore current velocity varies across the nearshore zone. The model simulates the undertow, hydraulic cell and rip-current patterns generated by radiation stresses and longshore variability in wave heights. Numerical results show that a non-uniform seabed is crucial for generation of rip currents in the nearshore (when bed slope is uniform, rips are not generated). Increasing the wave height increases the peaks of eddy viscosity and TKE (turbulent kinetic energy), while increasing the tidal amplitude reduces these peaks. Wave and tide interaction has most striking effects on the foreshore profile with the formation of the intertidal bar. High values of eddy viscosity, TKE and wave set-up are spread offshore for coarser grain sizes. Beach profile steepness modifies the nearshore circulation pattern, significantly enhancing the vertical component of the flow. The local recirculation within the longshore current in the inshore region causes a transient offshore shift and strengthening of the longshore current. Overall, the analysis shows that, with reasonable hypotheses, it is possible to simulate the nearshore hydrodynamics subjected to oceanic forcing, consistent with existing understanding of this area. Part II of this work presents 3D nearshore morphodynamics induced by the tides and waves.

• Korean Journal of Microbiology
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• v.17 no.2
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• pp.81-93
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• 1979

The mycelium of Rhizopus nigricans was harvested at intervals during the sporulation periods, fractioned into various cell components and analyzed the con!eiits of various cell materials in order to clarify the optimum conditions of sporulation and some characteristics of the metabolism during tke sporulation periods. The changes in enzyme activities, such as amylase and protease, were also measured during the sporulation period,. 1. Mycelium in distilled water culture, as control, did not sporulate but mycelial mat cultured in Petridish without mutrient spourulated. Optimum temperature range for sporulation was $20{\sim}25^{\circ}C$. 2. During the sporulation and maturation periods, proteins, especially alkali-labile protein were decreased remarkably but free amino acid and ninhydrin reactive substances in acid soluble fraction were increased, compared with control. 3. Acid solable polyphosphate was decreased but acid insoluble polyphosphate was increased, during the sporulation. 4. Carbohydrate and hexosamine in acid soluble fraction were increased, while carbohydrate in alkali insoluble residual fraction was decreased during the sporulation periods. 5. Amounts of UV-absorbing material in deoxyribonucleic acid fraction was increased a little but those in ribonucleic acid fraction was decreased, compared with control. 6. Intracellular amylases and proteases activities insporulating mycelial mat were increased continuously during the sporulation and maturation periods.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1343-1350
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• 2000

The evolutionary structure of tip vortices has been investigated with a two-dimensional LDV system for a plain and a slotted blade, respectively. To analyze the effect of slots which bypasses a part of main stream into the tip face, velocity profiles, vortex sizes, their displacements and turbulence intensities during one revolution of the rotor were measured by the phase averaging process. For the comparison of circumferential velocity components of the plain blade and the slotted blade, the peak values of the slotted blade were lower than those of the plain blade, and axial velocity components of the slotted blade were considerably larger than those of the plain blade. The slotted rotor blade enlarged the core size and made the vortex delayed compared with those of the plain blade at the same wake ages. Turbulence profiles had peaks inside the core radii and decayed gradually in the radial direction of vortex coordinate. Also, using a quasi 3-D LDV measurement technique the budget of turbulence kinetic energy was analyzed in radial direction of the vortex core.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.531-538
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• 2002

Flow characteristics of a round jet with swirl number of 0.17 have been investigated using a hot -wire anemometry in the initial region within 10D(exit diameter). Swirl effects were observed by comparing centerline flow characteristics, similarities and turbulent budgets of a swirl jet and a free jet, respectively. To obtain similarity of the radial profiles mean velocity and higher moments were measured at the vertical pl anes, located at 2.5, 5.0, 7.5D, 10D, respectively. The centerline velocity characteristics were also measured. It is turned out that similarities of mean and Reynolds stress are established. The jet boundary has wider width than that of a free jet and the shear stress also becomes stronger. In addition the centerline decay becomes faster than that of the free jet, indicating that the swirl induces more entrainment in the initial region of the swirl Jet by transferring the axial mean kinetic energy into the swirl energy and, therefore, has wider boundary, compared with that of free jet.

• Journal of the Korean Society of Clothing and Textiles
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• v.13 no.4
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• pp.330-338
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• 1989

The Korean apparel manufacturing industry started to meet domestic demands which had depended on importation in 1950s, growing into one of the export-oriented industries with several Five-Year Economic Development Plans. In spite of the development, inefficient organization of distribution of apparel manufacturing industry which connects production with consumption impedes further development of the industry. This study aims at suggesting desirable distribution system of ladies' apparel, the core of the fashion industry. This researcher interviewed those who are concerned in twenty-eight ladies' apparel manufacturing compaines, analyzing the current state of distribution in the industry and the problems. The results are as follows; 1. Forty-five percent of ladies' apparel is distributed through department stores. Therefore, the department stores need to assume their roles in sales and try to improve the condition and to train professional buyers. 2. The sales network is concentrated on the five biggest cities such as Seoul, Pusan, Taegu, Taechon, and Kwangju, prompting the need to be diversified. 3, Tke existing distribution forms distribution systems have many irrational factors which are aggravnting the rate of goods in stock. 4. The manufacturing companies do not implement studies on distribution. The companies should try to establish clear concepts on production and distribution on their own for better planning skills. 5. Computerized systems need to manage the procedures ranging from ordering, distribution, sales to inventory.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.147-156
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• 2006

Metropolitan Subway, tke volume of station, distance between station is short. when the demand is concentrated during moving peak periods, the Headway that than Line Headway in which Station Headway is applied to Station Capacity computation be. The factors to determine the Station Headway have a fixing Price of the machine and the Dwell time. Other factors aye decided already or fixing price but the Dwell time that change according to demand cause the biggest effect at Station Headway. After analyze constituents that influence to Station Headway in this study calculated correct Station Capacity drawing estimating dwell time model that change according to demand.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.35-43
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• 1992

Handling the emergency problems such as Chemobyl accident require real time prediction of pollutants dispersion. One-point real time sounding at pollutant source and simple model including turbulent-radiation process are very important to predict dispersion at real time. The stability categories obtained by one-dimensional numerical model (including PBL dynamics and radiative process) are good agreement with observational data (Golder, 1972). Therefore, the meteorological parameters (thermal, moisture and momentum fluxes; sensible and latent heat; Monin-Obukhov length and bulk Richardson number; vertical diffusion coefficient and TKE; mixing height) calculated by this model will be useful to understand the structure of stable boundary layer and to handling the emergency problems such as dangerous gasses accident. Especially, this simple model has strong merit for practical dispersion models which require turbulence process but does not takes long time to real predictions. According to the results of this model, the urban area has stronger vertical dispersion and weaker horizontal dispersion than rural area during daytime in summer season. The maximum stability class of urban area and rural area are "A" and "B" at 14 LST, respectively. After 20 LST, both urban and rural area have weak vertical dispersion, but they have strong horizontal dispersion. Generally, the urban area have larger radius of horizontal dispersion than rural area. Considering the resolution and time consuming problems of three dimensional grid model, one-dimensional model with one-point real sounding have strong merit for practical dispersion model.al dispersion model.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.20-29
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• 2010

The complicated flow characteristics of upper propeller wake influenced by hull wake are investigated in detail in the present study. A two-frame PIV (particle image velocimetry) technique was employed to visualize the upper propeller wake region. As the upper hull wake affects strongly propeller inflow, upper propeller wake shows much unstable vortical behavior, especially in the tip vortices. Velocity field measurements were conducted in a cavitation tunnel with a simulated hull wake. Generally, the hull wake generated by the hull of a marine ship may cause different loading distributions on the propeller blade in both upper and lower propeller planes. The unstable upper propeller wake caused by the ship's hull is expressed in terms of turbulent kinetic energy (TKE) and is identified by using the proper orthogonal decomposition (POD) method to characterize the coherent flow structure in it. Instabilities appeared in the eigen functions higher than the second one, giving unsteadiness to the downstream flow characteristics. The first eigen mode would be useful to find out the tip vortex positions immersed in the unstable downstream region.