• Journal of Wind Energy
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• v.15 no.1
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• pp.82-90
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• 2024

Bio-fouling has positive aspects that are used as a fish resource, but there are also negative aspects such as corrosion of the surface of the support structure, aesthetics and work safety problems. A specimen was produced using a polyurea material with excellent anti-fouling and methodology, and contact angle, high water pressure, adhesion, and real sea area tests were performed. As a result of measuring the contact angle of the specimen with a 10 cm x 10 cm area of polyurea, There was found to be an average of 124.4 ° at nine points. No surface damage was found even above 5 Mpa when high water pressure was sprayed, and adhesive strength of 300LSE adhesives was confirmed between 22.84 and 23.04 Mpa with an adhesion test. During the 6-month real sea area test, it was confirmed that about 17.24 % of the polyurea film was less generated than the comparison group.

• Journal of Chest Surgery
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• v.15 no.2
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• pp.259-265
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• 1982

We have designed a new type of bubble oxygenator (KOREA-KIM VENOTHERM OXYGENATOR) made of PVC sheet and deforming mesh incorporated in the heat exchanger, and evaluated in experimental animal for the analysis of it`s efficiency. The Oxygenator has low priming volume with high flow rate up to 6 L/rain, and efficiency of heat exchanger was excellent as 1-$1.5^{\circ}C.$ using total cardiopulmonary bypass method under moderate to deep hypothermia. Average priming volume of 1317 ml with 30% hemodilution method was perfused with an average of 1.1-3.0 L/min.$M^2$of arterial blood and pure oxygen at a rate of 2-3.4 L/min for 49.6 minutes continuously in average. During total cardiopulmonary bypass, average $PaO_2$ was $159.8{\pm}60$mmHg, $PaCO_2$ $41.0{\pm}3$mmHg respectively under $SaO_2$ over 96% with systolic arterial pressure of 70 mmHg and CVP of 5-10 cm$H_2O$. Plasma free Hemoglobin was $7.0{\pm}4$ mg/dl with 25% drop of hemoglobin and hematocrit at the end of cardiopulmonary bypass. This KKV Oxygenator was observed to have excellent capabillty of oxygen and carbon dioxide gas transfer with small amount of blood trauma, and the efficiency of heat exchanger was satisfactory during cooling and rewarming of the bubbled blood. Disadvantages have included the somewhat poor deforming effect due to loose PVC fiber mesh, the extracompact character of Teflon filters, and the rough inner surface of the heat exchanger copper pipes.

• The Korean Journal of Community Living Science
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• v.25 no.3
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• pp.383-388
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• 2014

This study was examined the physical characteristics (geometry, yield strength, thousand-seeds weight, true density, and moisture content) required for mechanization-related technologies such as (harvesting, washing, transport, and drying). Large differences in the size and shape of boxthorn berries(Jangmyeong, Bullo, Chungmyeong, and Hokwang) are used to analyze these physical properties. The average diameter, volume, surface area, and sphericity rate are calculated using long and short diameters of the boxthorn berry according to its variety. Hokwang has the largest measured surface area, and Bullo, the smallest. Average yield strength is 1.78 kPa and the mechanical pressure of soft boxthorn berries is not more than 1 kPa. Bullo has the highest true density. The optimum drying time for the measurement of moisture content is 4 hours at the drying temperature of $100^{\circ}C$.

• Tribology and Lubricants
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• v.17 no.3
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• pp.236-243
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• 2001

In this study, flow factors are evaluated in terms of kurtosis using random rough surface generated numerically. As h/$\sigma$become large ø$\sub$x/, ø$\sub$y/, ø$\sub$fp/, approach to 1 and ø$\sub$s/, ø$\sub$fs/ to 0 asymptotically regardless of kurtosis. ø$\sub$x/, ø$\sub$y/, ø$\sub$fp/ increase with increasing kurtosis in the mixed lubrication regime. ø$\sub$s/, ø$\sub$fs/ is associated with an additional flow transport due to the combined effect of sliding and roughness. As h/$\sigma$ decreases ø$\sub$s/, ø$\sub$fs/ increase up to a certain point, and then decrease toward zero. This behavior can be attributed to the increasing number of contacts in the mixed lubrication regime. ø$\sub$x/ in the presence of elastic deformation on the surface is larger than ø$\sub$x/ in the absence of it because local film thickness(h$\sub$T/) increases by elastic deformation.

• Wind and Structures
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• v.19 no.4
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• pp.443-465
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• 2014

Hyperbolic thin-shell cooling towers have complicated vibration modes, and are very sensitive to the effects of group towers and wind-induced vibrations. Traditional aero-elastic models of cooling towers are usually designed based on the method of stiffness simulation by continuous medium thin shell materials. However, the method has some shortages in actual engineering applications, so the so-called "equivalent beam-net design method" of aero-elastic models of cooling towers is proposed in the paper and an aero-elastic model with a proportion of 1: 200 based on the method above with integrated pressure measurements and vibration measurements has been designed and carried out in TJ-3 wind tunnel of Tongji university. According to the wind tunnel test, this paper discusses the impacts of self-excited force effect on the surface wind pressure of a large-scale cooling tower and the results show that the impact of self-excited force on the distribution characteristics of average surface wind pressure is very small, but the impact on the form of distribution and numerical value of fluctuating wind pressure is relatively large. Combing with the Complete Quadratic Combination method (hereafter referred to as CQC method), the paper further studies the numerical sizes and distribution characteristics of background components, resonant components, cross-term components and total fluctuating wind-induced vibration responses of some typical nodes which indicate that the resonance response is dominant in the fluctuating wind-induced vibration response and cross-term components are not negligible for wind-induced vibration responses of super-large cooling towers.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.1
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• pp.85-93
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• 1995

Measurements of ground level ozone concentrations were made in a rural area of Chongwon (Choongbook Province) from June 1993 to July 1994. High values frequently exceeding 100 ppb (ambient air qualyty standard of Korea) were recorded. High ozone concentrations in the boundary layer were primarily correlated with the several meteorological parameters in warm seasons: pressure, radiation, temperature, precipitation and wind velocity. The annual average concentration of ozone at Chongwon was 17ppb, and this value was relatively higher than those for other cities in Korea. O$\_$3/ concentrations were observed to increase when the ridge of a surface anticyclone was passing over the region, and maximum values(.geq.100 ppb) were observed on the rear sides of high pressure centers and in the warm sectors of cyclones(well head of cold fronts). The ozone concentrations had a negative correlation with the concentration of primary pollutants(e.g., total hydrocarbons).

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.57-62
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• 2009

Recently, with the increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lens are unable to satisfy the required performance. An aspheric glass lens is fabricated by the high temperature and pressure molding using a tungsten carbide molding core, so precision grinding technology for the molding core surface are required. This paper reports a development of feedrate control grinding method for aspherical molding core using parallel grinding method. A plane molding core was ground using conventional and feedrate control grinding method. The performance of the feedrate control method was evaluated by measurement of surface roughness. The result indicated that the average surface roughness was reduced to 1.5 nm, which is more efficient than the conventional grinding method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.462-468
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• 2010

Fatigue crack growth caused by surface defects is one of the most important subjects for the evaluation and the assurance of safety in pressure vessels, piping systems, LPG/LNG fuel tank and other various structures. So, this paper aims to investigate the relationship between the surface roughness of fracture CT specimens and the moments on the specimen when doing fatigue test for the evaluation and the assurance of safety of structures from fatigue crack deconstruction. In this experiment, the CT specimens were loaded by a fatigue testing machine with changing loads until they are broken. The surface roughness of the fracture CT specimens was measured using 3D precise shape measuring equipment and digital holography. As a result of this study, It was identified that the average roughnesses are similar at the positions that has a same moments by comparing the results with the moments on the specimen according to the position.

• Journal of Korean Academy of Dental Administration
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• v.11 no.1
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• pp.38-46
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• 2023

Composite resins, commonly used in clinical practice, have been developed to improve aesthetics to obtain smooth surfaces. Although the restored composite resin has a smooth surface, it gradually becomes rough over time. Therefore, this study measured glossiness to evaluate the surface of various composite resins and attempted to evaluate the maintenance of glossiness of composite resins by observing surfaces that change to roughness. Specimens were produced using resin used in clinical practice: Gradia direct anterior (GA), Tetric N-Ceram (TN), Ceram.X Sphere TEC one (CX), Filtek Z350XT (FT), Estelite sigma quick (ES). After creating a smooth surface with slide glass, five locations were randomly selected to measure surface gloss, and the average was the representative value of the specimen. Roughness was applied to the specimen under water pouring at the same speed and pressure using SiC paper #2400, 1200, and 400. The gloss unit of different SiC papers was measured. To evaluate the gloss unit and gloss retention between composite resins, one-way analysis of variance and Tukey multiple comparisons test were used. As a result of the study, there was a difference in gloss unit of specimens produced under the same conditions. Although the degree differed depending on the composite resin, there was also a difference in gloss retention. Based on the findings, composite resins show differences in gloss due to their different characteristics. Ceram.X Sphere TEC one (CX) showing the lowest gloss retention and Estelite sigma quick (ES) showing the highest.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.49-55
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• 2006

The purpose of the present study is to analyse characteristics of the background noise for the broadband seismic stations in KMA. It is well known that the background noise arises continuously from long period microseism, sea waves, minute changes of atmospheric pressure, seasonal temperature change of the ground surface, culture activities, and etc. The background noise shows spatial and temporal changes and it has various characteristics such as its spectral amplitudes in frequency domain are not constant Such the background noise gives considerable influences on the quality of seismic record. To investigate annual variations, the background noise was separated into high frequency components of above 1Hz More larger average amplitude is found in winter than other seasons. The average amplitude for 12 seismic stations are compared. It is known that the background noise is considerably larger in stations located in island region such as Jeju, Ulleungdo, and Bagryeongdo seismic stations. However the noise is relatively small in inland stations such as Chuncheon, Chungju and Uljin seismic stations.