• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.145-152
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• 2001

The purpose of this study was to determine nitrogen dioxide(NO$_2$) decay rate by reaction between NO$_2$ and interior materials in Korean residence. The results of this research could be helpful to choose the interior construction materials and to study on reduction of indoor air pollutants. The results of this research are as follows; For 30 residences in Seoul and Incheon from October 2000 to march 2001, the mean of infiltration rate was 0.70$\pm$0.44 ACH, and single-detached houses (7 houses) and apartments (19 houses) were 0.97$\pm$0.55 ACH and 0.61$\pm$0.34 ACH, respectively. The $CO_2$ decay followed approximately first-order process ($R^2$=0.97$\pm$0.02). There existed a statistic significance in filtration rate between houses built in 1980’s and built in 1990’s by t-test (p<0.02). Mean of NO$_2$ decay rates in 26 residence3s except 4 residences was 0.94$\pm$0.49hr$^{-1}$ , and also 0.86$\pm$0.49hr$^{-1}$ , 0.97$\pm$0.50hr$^{-1}$ in single-detached houses and apartments, respectively. Mean NO$_2$ decay rates in houses built in 1980’s were 0.78$\pm$0.37hr$^{-1}$ , 1.33$\pm$1.03hr$^{-1}$ , respectively. Nothing were showed statistical significance among indoor temperature, indoor humidity, and NO$_2$ decay rate. However, NO$_2$ decay rates had a tendency to increase by increase of temperature and humidity. Average volume/surface of participated houses was 0.55$\pm$0.07m and mean NO$_2$ deposition velocity was calculated as 1.46$\pm$0.59msec$^{-1}$ .

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4019-4023
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• 2014

This study examined the effectiveness of ultrasound on enhancing the dewaterability and volume reduction of bio solids from a waste treatment plant. The test specimen was obtained from a storage tank immediately before the dewatering process at a local treatment plant. The test conditions included the energy levels of ultrasonic waves and treatment time. The tests were undertaken using three types of different treatment processors (7 liter, 1 ton, 7 ton container). The capillary suction time (CST) and the viscosity of sludge, which is one of the influencing factors for dewaterbility, were obtained under various test conditions. The results showed that ultrasound increases the CST of the raw specimens, whereas a significant reduction (20 % of the maximum value) of CST occurred in the sample with ultrasound and flocculent. The decrease in viscosity reached 40 % of the maximum value. A centrifugal test was performed to examine the characteristics of the sludge settlement. The settling rate and time required to reach the final values were both enhanced by the ultrasonic energy. An ultrasonic treatment is potentially useful tool for reducing the amount of released sludge. To examine the possible use of field application, the real scale sonic processor was designed and operated. The results were similar (50 % of the maximum value) to those of laboratory experiments.

• Journal of the Korean Institute of Gas
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• v.26 no.6
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• pp.16-23
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• 2022

In this study, characteristics of effect on hydrogen gas was investigated to hydrogen embrittlement by disk and tensile tests. The developed and commercial alloy was fabricated to a plate material made from an alloy ingot. The prepared materials were processed in the form of a disk to measure rupture pressure by hydrogen and helium gas at a rate of 0.1 to 1,000 bar/min. In the hydrogen pre-charged tensile test, a specimen was hydrogenated using an anode charging method, and the yield strength, ultimate tensile strength, elongation, and reduction in area rate were carried by a strain rate test. Also, the microstructure was observed to the fracture surface of the tensile test specimen. As a result, the developed materials satisfied endurable hydrogen embrittlement, and the fractured surface showed a brittleness fracture surface with a depth of several ㎛, but dimple due to ductile fracture could be observed.

• Quality Improvement in Health Care
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• v.19 no.1
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• pp.64-72
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• 2013

Objective: To improve customer satisfaction through accurate information using computerized automation of the test reservation system and by performing all fasting tests on the same day with one fasting. Methods: Quality improvement activities of the test reservation system of Seoul National University Bundang Hospital improves internal and external customer satisfaction at the time of test scheduling by having the reservation system reflect test order and test time automatically and making the system to increase the same day test reservation rate. Results: Test process was smooth due to accurate test reservation and information based on test priority due to the introduction of the computerized test reservation system. Internal and external customer satisfaction improved due to the marked reduction in time required for making a reservation thanks to the improvement of work process. Conclusion: Building a computerized test reservation system was an effective measure to improve external and internal customer satisfaction.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.4
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• pp.580-597
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• 2013

Three materials SUS304, 9% Ni steel and Al 5083-O alloy, which are considered possible candidate for International Maritime Organization (IMO) type B Cargo Containment System, were studied. Monotonic tensile, fatigue, fatigue crack growth rate and Crack Tip Opening Displacement tests were carried out at room, intermediate low ($-100^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures. The initial yield and tensile strengths of all materials tended to increase with decreasing temperature, whereas the change in elastic modulus was not as remarkable. The largest and smallest improvement ratio of the initial yield strengths due to a temperature reduction were observed in the SUS304 and Al 5083-O alloy, respectively. The fatigue strengths of the three materials increased with decreasing temperature. The largest increase in fatigue strength was observed in the Al 5083-O alloy, whereas the 9% Ni steel sample showed the smallest increase. In the fatigue crack growth rate test, SUS304 and Al 5083-O alloy showed a decrease in the crack propagation rate, due to decrease in temperature, but no visible improvement in da/dN was observed in the case of 9% Ni steel. In the Crack Tip Opening Displacement (CTOD) test, CTOD values were converted to critical crack length for the comparison with different thickness specimens. The critical crack length tended to decrease in the case of SUS304 and increase for the Al 5083-O alloy with decreasing temperature. In case of 9% Ni steel, change of critical crack length was not observed due to temperature decrease. In addition, the changing material properties according to the temperature of the LNG tank were analyzed according to the international code for the construction and equipment of ships carrying liquefied gases in bulk (IGC code) and the rules of classifications.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.338-345
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• 2020

Versatile Video Coding (VVC), which has been developing as a next generation video coding standard, has adopted various techniques to achieve more than twice the compression performance of HEVC (High Efficiency Video Coding). The recently released VVC Test Model (VTM) shows 38% Bjontegaard Delta bitrate (BD-rate) improvement and 9x/1.6x encoding/decoding complexity over HEVC. In order to reduce such increased complexity, various fast algorithms have been proposed. In this paper, gradient-based methods of fast intra mode decision and block splitting are presented. Experimental results show that, compared to VTM6.0, the proposed method gives up to 65% encoding time reduction with 3.54% BD-rate loss in All-Intra (AI) configuration.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.369-377
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• 2014

This study was carried out to evaluate the effect of rice husk (RHB) and food waste biochar (FWB) on upland soil with sandy loam texture, in terms of physico-chemical analysis, lettuce seed germination test, and orgainc carbon leaching experiment. RHB and FWB had different physico-chemical properties each other. Carbon to nitrogen ratio (C/N ratio) of RHB was 32, showing two times higher than that of FWB. FWB had high salt and heavy metal content, compared to RHB. This is probably due to different ingredients and production processing between two biochars each other. Results of germination test with Lettuce showed lower germination rate when FWB was applied because of higher salt concentration compared to control and RHB. Organic carbon leaching test using saturated soil column (${\Phi}75{\times}h75mm$) with $10MT\;ha^{-1}$ biochar application rate, showed higher saturated hydraulic conductivity in rice husk biochar treatment column, compared to control and food waste biochar treatment. The highest total organic carbon concentration in column effluent was lower than those in both of rice husk biochar and food waste biochar, whereas the differences was negligible after 9 pore volumes of effluent. Consequently, biochars from byproducts such as rice husk and food waste in sandy loam textured upland soil could enhance a buffer function such as reduction of leaching from soil, but the harmful ingredient to crops such as high salt and heavy metals could limit the agricultural use of biochars.

• Korean Journal of Adult Nursing
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• v.14 no.1
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• pp.34-43
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• 2002

More and more non-injured operations are being implemented these days, thanks to the development of medical technology. Still, however, most operations leave direct scars on patient' bodies, as well as accompanying pain. The massage as an independent nursing intervention can stimulate the circulation of the blood of tissue and muscle and increase the relationship between a patient and a nurse. The purpose of this study is to investigate the effect of foot massage on pain in post abdominal operative patients. The nonequivalent control group, pre-post test design is used for this study. From July 7, 2000 to February 20, 2001, the 40 patients who were operated under general anesthesia in a university hospital in Seoul were studied. They were divided into two groups ; 20 patients were part of the experimental group, and the others, in the control group. In order to evaluate the effect of foot massage, severity of pain was checked with the VAS (Visual Analog Scale) and also each patients' vital signs were measured with pulse rate, systolic blood pressure and diastolic blood pressure. The collected datas were processed by SAS version 6.12 program and analyzed by the Chi-square, Fisher's exact test, t-test and repeated measures ANOVA. The results of this study were as follows. 1. The severity of pain decreased significantly in the experimental group as compared to the control group following foot massage (t=-3.317, p= .002). 2. Measured vital signs in the experimental group had more reduction of that than in the control group following foot massage. - The pulse rate in the experimental group was lower than that in the control group following foot massage (F=7.73, p=.008). - The systolic blood pressure in the experimental group was lower than that in the control group following foot massage (F=25.75, p=.000). - The diastolic blood pressure in the experimental group was lower than that in the control group following foot massage (F=15.27, p=.000). In conclusion, foot massage is an effective dependent nursing intervention for pain control of post abdominal operative patients.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.1
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• pp.38-49
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• 2016

This paper proposes a mathematical model-based solution for sourcing decisions with an objective of minimizing the manufacturer's total cost in the two-echelon supply chain with supply capacity risk. The risk impact is represented by uniform, beta, and triangular distributions. For the mathematical model, the probability vector of normal, risk, and recovery statuses are developed by using the status transition probability matrix and the equations for estimating the supply capacity under risk and recovery statuses are derived for each of the three probability distributions. Those formulas derived are validated using the sampling method. The results of the simulation study on the test problem show that the sourcing decisions using the proposed solution reduce the total cost by 1.6~3.7%, compared with the ones without a consideration of supply capacity risk. The total cost reduction increases approximately in a linear fashion as the probability of risk occurrence or reduction rate of supply capacity due to risk events is increased.

• ETRI Journal
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• v.36 no.3
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• pp.407-417
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• 2014

A new-generation video coding standard, named High Efficiency Video Coding (HEVC), has recently been developed by JCT-VC. This new standard provides a significant improvement in picture quality, especially for high-resolution videos. However, one the most important challenges in HEVC is time complexity. A quadtree-based structure is created for the encoding and decoding processes and the rate-distortion (RD) cost is calculated for all possible dimensions of coding units in the quadtree. This provides a high encoding quality, but also causes computational complexity. We focus on a reduction scheme of the computational complexity and propose a new approach that can terminate the quadtree-based structure early, based on the RD costs of the parent and current levels. Our proposed algorithm is compared with HEVC Test Model version 10.0 software and a previously proposed algorithm. Experimental results show that our algorithm provides a significant time reduction for encoding, with only a small loss in video quality.