• Journal of the Korean Society of Marine Environment & Safety
• /
• v.16 no.3
• /
• pp.301-306
• /
• 2010

DME(Di-Methyl Ehter, $CH_3OCH$) is currently attracting worldwide attention due to its environmentally friendly characteristics. Until now it was researched as a major alternative fuel of diesel automobile because it is a clean fuel producing low soot. Therefore, in this study, in order to investigate the effect of DME mixing on number density and size of soot particle, DME has been mixed in opposed-flow ethylene diffusion flame with the mixture ratios 5%, 14% and 30%. A laser extinction/scattering technique has been adopted to measure the volume fraction, number density, and size of soot particles. The experimental results showed that the soot concentration of mixture flames with the mixture ratios 5% and 14% produces soot more, even though that of 30% was decreased. This means that even though DME has been known to be a clean fuel for soot formation, the mixing of DME in diffusion flame of ethylene, where acetylene maintains high concentration in soot formation regions, could produce enhanced production of soot.

• Clean Technology
• /
• v.23 no.1
• /
• pp.1-14
• /
• 2017

At high nitrate concentrations, water must be treated to meet regulated concentrations because it results in threat to human health and eutrophication of natural water. However, it is almost impossible to remove nitrate by conventional water treatment methods such as coagulation, filtration and precipitation, due to its high water solubility. Therefore, other technologies including adsorption, ion exchange, reverse osmosis, denitrification, and electrodialysis are required to effectively remove nitrate. Each of these technologies has their own strengths and drawbacks and their feasibility is weighted against factors such as cost, water quality improvement, residuals handling, and pre-treatment requirements. An adsorption technique is the most popular and common process because of its cost effectiveness, ease of operation, and simplicity of design. Surface modifications of adsorbents have been enhanced their adsorption of nitrate. The nitrate-selective membrane process of electrodialysis reversal and reverse osmosis have proven over time and at many locations to be highly effective in removing nitrate contaminating problems in aqueous solutions. Both electrodiaysis and reverse osmosis methods generate highly concentrated wastes and need careful consideration with respect to disposal.

• Journal of Korean Academy of Nursing
• /
• v.8 no.2
• /
• pp.79-88
• /
• 1978

Utilizing Foley catheter in therapy of inpatient cause bacteriuria and urinary tract infection that leads to first ranked factor's in hospital infection (nosocomial infection). To protect the patient from such infections, emphasis should be placed on catheterization technique and management of the closed drainage system, this reducing the chances of introducing organisms. This study has been done at Intensive Care Unit of A and B hospitals from May-Oct. 1978 on 20 male and 18 female adult patients. Each patient was screened and found to have nonbacteriuria in clean catch specimen before catheterization. Clean catch specimen via foley catheter were obtained after 48 hours and 96 hours from catheterization. The findings are as follows: A. The occurrence of bacteriuria in patients according to duration of indwelling catheter. 1 213.9% of the patient showed evidence of bacteriuria 48h post catheterization specimen, while 57.9% of the patient showed evidence of bacteriuria 96h post catheterization specimen. 2 25% of male patients had infection 48h post catheterization and 45% displayed bacteriuria post catheterization. 33％ of female patients displayed infection 48h post catheterization and 72.2% having infection 96h post catheterization. Statistically there were significant differences between female patients and the duration of insertion. (P < 0.025) B. The occurrence of bacteriuria with the administration of bacteriuria with the ad-ministration of antibiotic in 24 patients was in 41,7%. The occurrence of bacteriuria without the administration of antibiotic in 14 patients was in 92.3%. Statistically there were very significant difference between the administration of the antibiotis and bacteriuria. (P < 0.005) C. Studies were done according to the consciousness level of the patients, 71.4% of those patient who displayed mental disorder developed bacteriuria, while 30.0% of those patient who displayed non mental disorder developed bacteriuria.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.1
• /
• pp.81-89
• /
• 2018

Fuel blend technique is one of the most effective way of using biomass to replace the coal. Many studies on combustion characteristics with coal and biomass blends have been conducted. In this study, char reactivity and emission characteristics of coal (Suek) and biomass (EFB) blends has been investigated by TGA and DTF to evaluate the applicability of the pre-treated (torrefaction, ash removal technology) EFB to pulverized coal boiler. In all blending cases, char reactivity improved as the blending ratio increases (10, 20, and 30%), especially torrefied EFB blended at 30%. Also, unburned carbon decreased as the blending ratio increases in all types of EFB. NOx emission showed the increase and decrease characteristics according to the content of fuel-N of raw EFB and torrefied EFB. But the amount of NOx emission at ashless EFB blends is greater than that of Suek despite of lower fuel-N. It indicated that co-firing effect of using the pretreatment biomass fuel is relatively better than those of the untreated biomass fuel about char reactivity and emission characteristics.

• Proceedings of KOSOMES biannual meeting
• /
• 2007.11a
• /
• pp.43-49
• /
• 2007

The metals we are familiar with(Al, Ag, Au, Cu, Cd, Co, Fe, Ni, Pb, Zn, etc) are common elements and conservative pollutants. Although metals are often vital constituents of the metabolism of living organisms(trace elements}, a number of them are toxic if their concentration exceeds a certain threshold. It has long been recognized that measurements of trace metals in natural waters are often subject to large errors in terms of precision and accuracy. Since 1975 in US and European countries, seawater concentration of many trace metals have been shown to be factors of 10-1,000 lower than those previously accepted. Vertical profiles have been found to be consistent with known biological, physical and/or geochemical processes. These are resulted from major advances in analytical instrumentation and methodology for trace elements, and greater attention has been given to assuring the elimination of contamination during sampling, storage, and analysis.

• The Journal of the Acoustical Society of Korea
• /
• v.16 no.6
• /
• pp.94-99
• /
• 1997

This paper describes a technique of probabilistic spectral subtraction which uses the knowledge of both noise and speech so as to reduce automatic speech recognition errors in noisy environments. Spectral subtraction method estimates a noise prototype in non-speech intervals and the spectrum of clean speech is obtained from the spectrum of noisy speech by subtracting this noise prototype. Thus noise can not be suppressed effectively using a single noise prototype in case the characteristics of the noise prototype are different from those of the noise contained in input noisy speech. To modify such a drawback, multiple noise prototypes are used in probabilistic subtraction method. In this paper, the probabilistic characteristics of noise and the knowledge of speech which is embedded in hidden Markov models trained in clean environments are used to suppress noise. Futhermore, dynamic feature parameters are considered as well as static feature parameters for effective noise suppression. The proposed method reduced error rates in the recognition of 50 Korean words. The recognition rate was 86.25% with the probabilistic subtraction, 72.75% without any noise suppression method and 80.25% with spectral subtraction at SNR(Signal-to-Noise Ratio) 10 dB.

• Clean Technology
• /
• v.11 no.3
• /
• pp.147-152
• /
• 2005

For estblishing the best technique for the micronization of Ibuprofen using supercritical fluids, the solubility should be known. The solubility of Ibuprofen in supercritical carbon dioxide was measured by observing the cloud point. The cloud point was observed using high pressure equipment equipped a variable volume view cell between temperature of 35, 40 and $45^{\circ}C$. The solubility data was correlated by the Peng-Robinson equation of state Solute physical properties, such as critical temperature (Tc), critical pressure (Pc) and acentric factor (${\omega}$) were estimated by the some group contribution method. As pressure was increased, the solubility increased at constant temperature. The retrograde phenomenon by a solute vapor pressure and a density of solvent was observed at the pressure of around 150bar. It was found that $CO_2$ can be used as a supercritical solvent in micronization of ibuprofen by RESS.

• Clean Technology
• /
• v.20 no.3
• /
• pp.314-320
• /
• 2014

The purpose of this work is to optimize composition of mixture refrigerants used in the C3MR (Propane & Mixed Refrigerants) process by a statistical optimization technique. C3MR studied in this work is one of widely used commercial natural gas liquefaction processes with high efficiency. Process simulation was performed in a commercial process simulator and methane ($C_1$), ethane ($C_2$), propane ($C_3$), and nitrogen ($N_2$) were selected as mixed refrigerants. Using the process model, optimum composition of refrigerants mixture was determined via mixture design and central composite design to produce minimum energy consumption. As a result, it was confirmed that energy consumption is reduced down to 11.3% comparing to existing design. It was also compared with heat effectiveness through temperature profile of MCHE (main cryogenic heat exchanger).

• Journal of the Korean Society of Clothing and Textiles
• /
• v.37 no.3
• /
• pp.270-279
• /
• 2013

This study presents a T-shirt design process that utilizes modernized traditional patterns; in addition, it also includes various modernization techniques for Korean traditional patterns. T-shirts are a representative casual wear item worn in everyday life, especially among young people. The association of traditional elements and public goods such as T-shirts effects the diffusion of the Korean image into global society. Through the whole design process, target groups and design concepts were determined first: collegiate students as well as clean, natural, refined, simple and sporty image, respectively. Subsequently, Dokkaebi, lotus, Dangcho, dragon and Taegeuk patterns were selected as traditional pattern sources. Along with the technique of the division, transformation, and configuration of original patterns, the combining method of geometrical figures, stripe patterns, and check patterns with traditional patterns was helped create modernized traditional motives. Finally, T-shirt designs with a Korean image were developed with the harmonized deployment of modernized motives and color planning. The survey showed that designs had a clean, natural, refined, simple and sporty image that was preferred by collegiate students. This study is relevant in three aspects. First, the design process of modernization was very creative to combine traditional patterns and basic figures. Second, this study expanded the scope of traditional image design to casual wear to promote the Korean image to young people all over the world. Third, the whole design process, from planning to final product development, presented in this study is applicable to other design processes.

• Clean Technology
• /
• v.10 no.2
• /
• pp.111-120
• /
• 2004

Manufacturing with a chemical for eco-friendly leather for nitrogen decrease of leather falling hair process waste water and the falling hair process that a number to decrease with sulfuration water decrease, a pollution load of COD, BOD. In this study manufactured lining agent and the unhairing assist product which did urea, mercaptan by basic matter. As a result of having dealt in hair saving process, compared, and was recalled by the existing hair burning process recovered hair, increased approximately 2times. Grain state to influence the yield that was quality of leather and an index of productivity evaluation, an improvement of contraction phenomenon (drawing) were possible. Is increased going seal, tear strength property of matter and softness and touch leather native nature in wet blue. Also, it is possible confirmation with decrease being more possible than about 50% COD, T-N density in a hair saving waste water.