• KSCE Journal of Civil and Environmental Engineering Research
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• 제34권3호
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• pp.919-930
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• 2014

In this study, the load capacities and behaviors of a shotcrete member with steel supports, as composite member, are investigated numerically by using a fiber section element. The cross section of a shotcrete lining with steel support is divided into a bundle of fibers, which are allocated nonlinear stress-strain relations and used for determining internal forces. To verify the used approach of the finite element method for shotcrete with steel supports, the load-displacement relations of shotcrete lining obtained by numerical analysis are compared with existing experimental results and are analyzed with the stress distribution of the shotcrete and steel support obtained numerically. As a result, it is shown that the proposed approach can predict the load capacities of each material and the overall nonlinear behavior of shotcrete lining with steel supports. The change of location of the neutral axis and the flexural resistance ratio of each material are also derived from the stress distribution of the cross section of the shotcrete lining with steel supports. From the results, it is concluded that the flexural resistance performance of steel support should be considered in shotcrete lining design.

• Journal of Biomedical Engineering Research
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• 제23권3호
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• pp.217-225
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• 2002

The implantable middle ear(IME) system, which has good sound quality. superior sound intelligibility and wide frequency characteristics. can resolve the sound distortion and ringing effect by sound feedback at high gain operation those are the major problems of conventional hearing aid. In this paper, we have manufactured the IME system using differential electromagnetic transducer(DET) and verified the performance of the system by carrying out vibration and animal implanting experiment. The DET was manufactured using micro-machining technology and vibration experiment of the transducer was performed to inspect whether the transducer could vibrate in accordance with the applied sound signal or not. And the result of the loaded experiment using temporal bone sampled from cadaver showed that the transducer can drive the middle ear bone and transmit the signal to inner ear After the internal unit of IME system was implanted in a dog. the auditory brainstem response (ABR) test was carried out. The result of the test indicated the Proper behavior of the IME system in the living body From the results of the experiments, it is verified that the manufactured system ewll work well when it is applied to human and a basis of clinical experiment of IME system to real human hearing impaired was be arranged.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.210-218
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• 2000

Since the SSC(soluble solid contents) and titratable acidity of fruit are highly concerned to the taste, the need for measuring them by non-destructive technology such as NIR(Visual and Near-infrared) spectroscopy is increasing. Specially, in order to grade the quality of each fruit with a sorter at sorting and packing facilities, technologies for online measurement satisfying the tolerance in terms of accuracy and speed should be developed. Many researches have been done to develop devices to measure the internal qualities of fruit such as SSC, titratable acidity, firmness, etc. with the VIS(Visual)/NIR(Near Infrared) reflectance spectra. The distributions of the SSC, titratable acidity, firmness, etc. are different with respect to the position and depth of fruit, and generally the VIS/NIR light can interact with fruit in a few millimeters of pathlength, and it is very difficult to measure the qualities of inner flesh of fruit. Therefore, to measure the average concentrations of each quality factor such as SSC and titratable acidity with the reflectance-type NIR devices, the spectra of fruit at several positions should be measured. Recently, the interest about the transmittance-type VIS/NIR devices is increasing. NIR light can penetrate through the fruit about 1/10-1/1,000,000 %. Therefore, very intensive light source and very sensitive sensor should be adopted to measure the transmitted light spectra of intact fruit. The ultimate purpose of this study was to develop a device to measure the transmitted light spectra of intact fruit such as apple, pear, peach, etc. With the transmittance-type VIS/NIR device, the feasibility of measurement of the SSC and titratable acidity in intact fruit cultivated in Korea was tested. The results are summarized as follows; A simple measurement device which can measure the transmitted light spectra of intact fruit was constructed with sample holder, two 500W-tungsten halogen lamps, a real-time spectrometer having a very sensitive CCD array sensor and optical fiber probe. With the device, it was possible to measure the transmitted light spectra of intact fruit such as apple, pear and peach. Main factors affecting the intensity of transmitted light spectra were the size of sample, the radiation intensity of light source and the integration time of the detector. Sample holder should be designed so that direct light leakage to the probe could be protected. Preprocessing method to the raw spectrum data significantly influenced the performance of the nondestructive measurement of SSC and titratable acidity of intact fruit. Representative results of PLS models in predicting the SSC of peach were SEP of 0.558 Brix% and R2 of 0.819, and those in predicting titratable acidity were SEP of 0.056% and R2 of 0.655.

• Journal of Preventive Medicine and Public Health
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• 제29권1호
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• pp.51-65
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• 1996

The purpose of this study was to examine the trends of length of hospital stay (LOS), which is most likely to be a major attribute to hospital performance. From 1984 to 1994, an average LOS of each hospital was analyzed by factors such as medical departments, bed size, occupancy rate, region and ownership. This study was analyzed changing rate of LOS during 11 years. This rate was calculated by simple regression, which was used only with hospital without missing data during 11 years. This study findings are as follows. 1. The results indicated that the average LOS was steadily increased until 1990 but it was slightly decreased after 1990. 2. This trend could be found in all hospital scale and all group of occupancy rate. Specifically this trends of LOS were found in internal medicine, corporate owned hospitals, and hospitals in major city. But LOS of individual owned hospital was continuously increased until 1994. 3. Means of changing rates of LOS were calculated from 1984 to 1994. If we devided it into two parts, before 1990 and after 1990, most changing rates of LOS before 1990 except individual owned hospital were found positive sign. The changing rates after 1990 were negative sign but small hospital(lesser then 200 bed), individual owned hospital, national & public hospital and hospital in small urban have little change of LOS after 1990. Finally from this results we thought that most hospitals in Korea began to be concerned with LOS. Nevertheless LOS of several hospital such as small hospital or individual owned hospital was increased. And this trend may be caused by a few patients, low occupancy rate, or low profit. This trend of LOS is different from that of other countries. Perhaps this phenomenon is resulted from the reimbursement method. Because of fee for service reimbursement system in Korea the hospitals didn't need to shorten LOS in order to save the cost and increase the profit. Therefore reform of hospital cost reimbursement method will be needed to reduce hospital cost in Korea. We thought that the Korean health authority should consider the reimbursement method by unit of bundle of services, for example DRG and prepayment in the United States. This study presents some limitations such as no insight of severity of disease, case-mix measurement of hospital, and other clinical characteristics that can. possibly affect LOS. However, this study reports an important trend in LOS from 1984 to 1994.

• The Korean Journal of Nuclear Medicine
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• 제31권1호
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• pp.50-56
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• 1997

Gated SPECT can evaluate the regional wall motion of the heart. We evaluated the regional wall motion of the perfusion abnormality in conventional perfusion SPECT with gated SPECT. In case of suspicious perfusion abnormalities, we tried to differentiate the artifact from true abnormality in coronary vascular disease using gated SPECT. We thought that artifacts would have normal wall motion, whereas fixed defects with decreased wall motion would probably represent coronary artery disease. A total of 275 patients who were performed coronary angiography and T1-201 rest/Tc-99m MIBI dipyridamole stress gated SPECT within 2 months were enrolled. In coronary angiography, stenosis more than 50% was considered as coronary artery disease. After injection of 111MBq T1-201 rest image was obtained on triple head SPECT system. 370MBg Tc-99m MIBI was used for the stress image. Eight-frame per-cardiac-cycle gated Tc-99m SPECT studies were done. All the images were analyzed visually. Using perfusion SPECT, the overall sensitivity and specificity were 87% and 55% respectively. Regarding artery territory, sensitivity and specificity were 68% and 73% for left anterior descending artery(LAD), 62% and 78% for right coronary artery(RCA), 42% and 90% for left ciramflex artery(LCX). Using gated SPECT, the overall sensitivity and specificity were 87% and 66% respectively. Sensitivity and specificity were 68% and 78% for LAD, 62% and 79% for RCA, 42% and 90% for LCX. Among 21 false positive cases in perfusion SPECT, 5 cases were interpreted as true negative with gated SPECT. We conclude that gated SPECT provides a valuable adjunct to perfusion SPECT in characterizing perfusion abnormalities and to improve specificity.

• International Journal of Highway Engineering
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• 제10권4호
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• pp.9-18
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• 2008

Curling is caused by the difference in the temperature and humidity by the depth of the slab in Jointed Plain Concrete Pavement. Slab curvature shape and size change due to curling exert a profound influence on the internal stress and roughness of the pavement, affecting structural and functional performance of the pavement. Direct measurement of the slab curvature entails many problems. Many measuring instruments have to be installed at the early-stage of the pavement construction, and the behavior of the slab curvature needs to be measured accurately from the early-stage. Moreover, the cost and technical difficulty are very formidable to measure the slab curvature. This study develops a measurement method for slab curvature in jointed concrete pavement at any given time by applying Power Spectrum Density Analysis and Inverse Fast Fourier Transformation to the profile data, that can be easily obtained at the construction field site. The effectiveness of this developed method is verified by measuring the profile data of the test road of jointed concrete pavement at an inland central expressway by the hour and by examining the result of extracting the slab curvature shape from this profile data. Additionally, the profile data of CRCP(Continuously Reinforced Concrete Pavement) sections on the same expressway were obtained and analyzed at the same time. The validity of the method developed for the slab curvature shape extraction is verified by comparing the result from the analysis of the profile data of CRCP sections with that from the analysis of the prof1Ie data of jointed concrete pavement sections.

• Journal of Korea Soil Environment Society
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• 제4권2호
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• pp.137-147
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• 1999

Fluidized-bed thermal desorber coupled with a heat pipe was investigated for the remediation of soil contaminated with diesel oils. Thermal gravimetric analysis by Cahn-balance indicated that the desorption of diesel oils from the soil particles was mainly governed by the internal diffusion at low concentration of less than 0.5 wt. % of oils in the soil particles. In fluidized-bed experiments. increase of fluidizing gas velocity reduced the residual oils of the contaminated soils, the increase of soil feed rate decreased efficiency of fluidized-bed desorber. A mathematical model was developed by incorporating Fickian diffusion kinetics into the Kunii-Levenspiel model Simulation results showed reasonable agreement for the performance of fluidized-bed thermal desorber.

• Journal of the Society of Disaster Information
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• 제8권3호
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• pp.310-318
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• 2012

Actual condition by items based on the level of execution of Construction Company certified by Construction Safety and Health Management Systems (KOSHA 18001) was investigated, analyzed and evaluated reflecting various opinions fincluding safety experts, top management, audit experts, and construction engineers. Currently, the maintenance is being managed through internal audit after the safety and health management system has been certified, but it is difficult to identify the degree of continuous improvement. In order to present the standards to see the level of quantified system, this study was conducted. The purpose of this study is to present the system maturity evaluation tool to be used to reduce occupational accidents through proper establishment and continuous improvement of national health and safety management system. Results of this study are summarized through identification of current condition of implementation of KOSHA 18001 system, development of maturity measurement tool and verification as follows: First, priority of implementation for activities of headquarters and on-site was determined by importance of activities such as the risk assessment, safety and health accident prevention activities, performance assessment and monitoring, resource management and support, and management review and improvement in order. In addition, the expert group presented that association with continuous improvement activities could establish the system by presenting strengths, weaknesses and improvement subjects of system.

• Journal of Energy Engineering
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• 제28권4호
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• pp.35-41
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• 2019

In order to overcome these disadvantages, the halogen light source, which was previously used as a vehicle fog light, has increased power consumption and a short lifetime, and thus, an automobile light source is gradually being replaced with an LED. However, when the vehicle LED fog light is turned on, there is a disadvantage in reducing the life of the fog lamp due to the high heat generated from the LED. The heat generated by the LED inside the fog lamp is mainly emitted by the heatsink, but most of the remaining heat is released to the outside through convection. When cooling efficiency decreases due to convection, thermal energy generates heat to lenses, reflectors, and bezels, which are the main parts of lamps, or generates high temperatures in LED, thereby shortening the life of LED fog lights. In this study, we tried to improve the heat dissipation performance by convection in addition to the heat dissipation method by heat sink, and to determine the installation location of vents that can discharge the internal air or intake the external air of LED fog lamp for vehicle. Thermal fluid analysis was performed to ensure that the optimal data were reflected in the design. The average velocity of air increased in the order of Case3 and Case2 compared to Case1, which is the existing prototype, and the increase rate of Case3 was relatively higher than that of other cases. This is because the vents installed above and below the fog lamps induce the convective phenomena generated according to the temperature difference, and the heat is efficiently discharged with the increase of the air speed.

• Applied Chemistry for Engineering
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• 제18권5호
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.