• Korean Chemical Engineering Research
• /
• v.60 no.1
• /
• pp.132-138
• /
• 2022

In this study, a basic study was performed to systematically compare the changes in surface properties according to the post-processing method of the stereolithography (SLA) printing method, which is a photocuring 3D printing method, and to provide information on the post-processing method suitable for the application. Although it was possible to improve some of the transparency of the SLA-type output by regularly changing the irregular microstructure of the surface through polishing, it was difficult to secure sufficient transparency like glass. The change in contact angle characteristics due to grinding showed a tendency to slightly increase as the grinding time increased and the particle size of the sandpaper used was small, but the variation between samples was large and the average contact angle was 77~90°, showing no statistically significant difference. Surface treatment methods other than polishing were tried, and it was confirmed that it was possible to easily and simply improve the transparency by applying a commercially available vehicle scratch remover or silicone oil. In addition, a method for securing high transparency such as glass by using a scratch remover after sequential grinding while reducing the particle size of the sandpaper was proposed. Finally, even after surface treatment through polishing and various methods, it was difficult to secure a contact angle of 90° or more.

• Journal of Microbiology and Biotechnology
• /
• v.6 no.2
• /
• pp.103-109
• /
• 1996

Mn(II)+succinate decreased the carotenoid formation of the yeast Phaffia rhodozyma, probably by scavenging $O_2$. When duroquinone (DQ), an internal and external $O_2$ generator, was added to medium, P. rhodozyma produced more amount of carotenoids. The increased carotenoid production was destroyed by oxygen radical (OR) scavengers, ascorbate+Cu(II) and dimethylsulfoxide. When sub-lethal concentrations of $H_2O_2$ , an external OR source, and antimycin, an internal OR inducer, were used, the effect of $H_2O_2$ on carotenoid formation and composition was less significant than that of antimycin. Addition of superoxide dismutase, an external OR remover, rescued cells from death caused by the high concentration of DO. In this condition, the yeast culture showed an increase in carotenoid content. Addition of DQ into P. rhodozyma culture in the stationary phase did not increase carotenoid production. Therefore, carotenoid formation was stimulated by internal ORs in the growing yeast. It was probably due to release of catabolite repression on carotenogenesis in the yeast. Aeration was important for carotenoid production but was not as effective as the internal OR producer, DQ.

• Environmental Engineering Research
• /
• v.12 no.5
• /
• pp.203-210
• /
• 2007

Since the emissions composition from the household products have potentially been associated with health risks for building occupants, the chemical composition emitted from the products should be surveyed. The current study identified the emission composition for 42 liquid household products, using a purge-and-trap method. This evaluation was done by classifying the household products into five product classes (deodorizers, household cleaners, color removers, pesticides, and polishes). Nineteen compounds were chosen on the basis of selection criteria. The quality control program for purge-and-trap and analytical systems included tests of laboratory blank Tenax traps and blank water samples, and the determination of calibration equation, measurement precision, method detection limit (MDL), and recovery. The number of chemicals varied according to the product categories, ranging from 4 for the product category of bleaches to 12 for the product categories of air fresheners and nail color removers. For all product categories, the emission composition and concentrations varied broadly according to product. It is noteworthy that most household products emit limonene: 19 of 25 cleaning products; 5 of 6 deodorizers; 1 of 3 pesticides; 3 of 3 color removers; and 4 of 5 polishes. It was suggested that the use of household products sold in Korea could elevate the formation of secondary toxic pollutants in indoor environments, by the reaction of limonene with ozone, which entered indoor environments or might be generated by indoor sources such as electronic air cleaning devices and copying machines.

• Journal of IKEEE
• /
• v.22 no.1
• /
• pp.93-97
• /
• 2018

In this paper, it proposes a method that uses an air pump to inject oxygen to water directly to prevent the growth of algae and cyanobacterium using MCU(Micro Controller Unit). MCU can control itself with modules of GPS, a sonic sensor, camera, conveyer belt and water pump to remove and prevent growths of algae. It can also be connected to the smart phone application software to track the system where it is and it can be controlled by the user interfaced with the smart phone application.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.1
• /
• pp.1-6
• /
• 2015

Recently, According to increasing interest to original sound Karaoke instrument, MIDI type karaoke manufacturer attempt to make more cheap method instead of original recoding method. The specific method is to make the original sound accompaniment to remove only the voice of the singer in the singer music album. In this paper, a system to separate vocal components from music accompaniment for stereo recordings were proposed. Proposed system consists of two stages. The first stage is a vocal detection. This stage classifies an input into vocal and non vocal portions by using SVM with MFCC. In the second stage, selective frequency subtractions were performed at each frequency bin in vocal portions. Listening test with removed vocal music from proposed system show relatively high satisfactory level.

• The Journal of the Korea Contents Association
• /
• v.2 no.2
• /
• pp.73-84
• /
• 2002

In this paper, we propose a enhanced ERICA switch algorithm using the buffer management scheme which can reduce the queue length, support the efficiency link utilization and the fair share. It has three different buffer thresholds which are low threshold, congestion notification threshold and high threshold. According to the each buffer threshold status, switch announced congestion notification to the source differently. So, sources could know the congestion more quickly and fast remover from network congestion. As a experimental results, it is proved that proposed algorithm is the more efficient than ERICA. Especially, proposed switch algorithm provides congestion control mechanism to make the best use of with keeping fairness and reduce queue length.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.699-702
• /
• 2008

This paper describes the numerical simulations in the cooling of the radiator in a distribution transformer. The aim of this work is the cooling optimization of the transformer by CFD simulations. A clear understanding of the cooling pattern in a radiator which is a main heat remover in the power transformer is essential for optimizing the radiator design increasing the thermal efficiency. In this paper we study the heat transfer and fluid flow in a 3-phase 400kVA transformer. The plate radiators of this transformer become wrinkled (corrugated radiator) and there are filled with transformer oil. The oil is circulated due to the natural convection driven by buoyancy effects through radiators so that the ultimate cooling medium is the surrounding air. In the design of transformers, it is of interest to minimize the cost and size of radiators. The obtained results show the temperature and flow distributions and the possibility to optimize the transformer with 3-dimensional CFD models using FLUENT.

• 보존과학연구
• /
• s.30
• /
• pp.171-187
• /
• 2009

The Seated iron Vairocana Buddha statue of Dopiansa Temple, Cheolwon was designated National treasure No. 63, it is very important to rearch about Korean Buddha statue because it has an inscription on the back indicates that it was made in 865 A.D., the fifth year of the reign of King Gyeongmun(861-875) of Unified Silla(668-935), through the devoted faith of some 1,500 Buddhist followers of the Cheorwon-gun area. In this conservation treatment, for the Seated iron Vairocana Buddha statue of Dopiansa Temple, Cheolwon plating layer and cashew paint layer of the iron pedestal were removed and for the paint the Body of the Buddha, fake metal layer and plaster layer were removed, stabilizing treatment and coating treatment were done, and removal and restoration of earlobe which had been damaged and later was restored with plaster in the regilding in 1988, and the white hair on forehead was replaced with material of rock crystal, and conch-shaped hair damaged was restored on 35 spots.

• International Journal of Fluid Machinery and Systems
• /
• v.7 no.3
• /
• pp.125-129
• /
• 2014

The paint removal and recoating are the very important process in airplane maintenance. The traditional technology is to use the chemical way corroding the paint with paint remover. For changing the defects, corrosion & pollution & manual working, of the traditional technology, the physical process which removes the paint of airplane with 250MPa/250kW ultra-high pressure rotary water jetting though the surface cleaner installed on the six axes robot is studied. The paint layer of airplane is very thin and close. The contradiction of water jetting paint removal is to remove the paint layer wholly and not damage the surface of airplane. In order to solve the contradiction, the best working condition must be reached through tests. The paint removal efficiency with ultra-high pressure and move speed of not damaged to the surface. The move speed of this test is about 2m/min, and the paint removal efficiency is about $30{\sim}40m^2/h$, and the paint removal active area is 85-90%. No-repeat and no-omit are the base requests of the robot program. The physical paint removal technology will be applied in airplane maintenance, and will face the safety detection of application permission.

• Journal of Biosystems Engineering
• /
• v.19 no.4
• /
• pp.311-317
• /
• 1994

Warts and barks of apple trees were vector of White rot. Two devices removing warts and barks for the use of pest control on apple trees were developed and evaluated in this study, and their results are as follows ; 1. A total of 148 warts were examined to determine the average size. About 35 percent of the examined warts were 6~8mm long, 4~8mm wide and 4~6mm thick in size. About 30 percent of the examined warts were 4~6mm long, 2~4mm wide and 6~8mm thick in size. 2. Seventy-one percent of the examined barks removed were 4~8mm in thickness. 3. A blade with 30 degree of cutting angle required 3 to 22 percent less cutting energy than those with 15 and 45 degrees of cutting angles. 4. The cutting torque decreased from 31 N-cm to 12 N-cm with an increase of cutting speed from 26cm/s to 104cm/s for a feeding speed of 0.31 mm/s with the blade angle of 30 degrees. 5. The cutting torque increased from 6N-cm to 32N-cm with an increase of branch diameter from 6mm to 14mm for a feeding speed of 0.31 mm/s with the blade angle of 30 degrees. 6. Two devices mounted on a mower for removing warts and barks were evaluated and proved effective.