• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.21-31
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• 2017

Geobag method is an eco-friendly method to minimize the impact on the environment in the construction of retaining wall structure as a kind of geosynthetic reinforced retaining walls. In this study, evaluated behavior of full scaled geobag retaining wall about four different types of geobag retaining walls, that is, non-compacted geobags wall, compacted geobag wall, combination of longitudinal and transversal laied geobags wall, gabion and geobag wall were constructed in the field with instrumentation. Based on the results of field measurement, transversal layered geobag wall for non-compacted case was displaced 30% more than that of mixed gabion wall. Also, the more than 2m geobag walls without reinforcement at the backfill area are turned out to be unstable in terms of wall displacement. On the one hand, the distribution of the earth pressure for all geobag retaining walls sites show within the range of Rankine's and Coulomb's earth pressure after construction. But after intensity rainfall, the transversal laied geobag walls significantly increment of soil pressure. The geobag walls which constructed in the way of mixed wall systems such as gabion and geobag, longitudinal and transversal laied geobags are much stable with comparison of transversal laied geobag wall.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.141-154
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• 2015

In general, conventional criticality analysis for spent fuel transport/storage systems have been performed based on the assumption of fresh fuel concerning the potential uncertainties from number density calculations of actinide nuclides and fission products in spent fuel. However, these evaluation methods cause financial losses due to an excessive criticality margin. In order to overcome this disadvantage, many studies have recently been conducted to design and commercialize a transportation and storage cask applied to the Burnup Credit (BUC). This study conducted an assessment to ensure criticality safety for reactor operating parameters, axial burn-up profiles and misload accident conditions, which are the factors that are likely to affect criticality safety when the BUC is applied to the dual-purpose cask under development at the KOrea RADioactive waste agency (KORAD). As a result, it was found that criticality resulting from specific power, changed substantially and relied on conditions of low enrichment and high burn-up. Considering the end effect in the case of high burn-up produced a positive-definite result. In particular, the increment of maximum effective multiplication factors due to misloading was 0.18467, confirming that misload is a factor that must be taken into account when applying the BUC. The results of this study may therefore be utilized as references in developing technologies to apply the BUC to domestic models and operational procedures or preventing any misload accidents during the process of spent fuel loading.

• Journal of Periodontal and Implant Science
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• v.40 no.3
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• pp.105-110
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• 2010

Purpose: It has been reported that low-level semiconductor diode lasers could enhance the wound healing process. The periodontal ligament is crucial for maintaining the tooth and surrounding tissues in periodontal wound healing. While low-level semiconductor diode lasers have been used in low-level laser therapy, there have been few reports on their effects on periodontal ligament fibroblasts (PDLFs). We performed this study to investigate the biological effects of semiconductor diode lasers on human PDLFs. Methods: Human PDLFs were cultured and irradiated with a gallium-aluminum-arsenate (GaAlAs) semiconductor diode laser of which the wavelength was 810 nm. The power output was fixed at 500 mW in the continuous wave mode with various energy fluencies, which were 1.97, 3.94, and 5.91 $J/cm^2$. A culture of PDLFs without laser irradiation was regarded as a control. Then, cells were additionally incubated in 72 hours for MTS assay and an alkaline phosphatase (ALPase) activity test. At 48 hours post-laser irradiation, western blot analysis was performed to determine extracellular signal-regulated kinase (ERK) activity. ANOVA was used to assess the significance level of the differences among groups (P<0.05). Results: At all energy fluencies of laser irradiation, PDLFs proliferation gradually increased for 72 hours without any significant differences compared with the control over the entire period taken together. However, an increment of cell proliferation significantly greater than in the control occurred between 24 and 48 hours at laser irradiation settings of 1.97 and 3.94 $J/cm^2$ (P<0.05). The highest ALPase activity was found at 48 and 72 hours post-laser irradiation with 3.94 $J/cm^2$ energy fluency (P<0.05). The phosphorylated ERK level was more prominent at 3.94 $J/cm^2$ energy fluency than in the control. Conclusions: The present study demonstrated that the GaAlAs semiconductor diode laser promoted proliferation and differentiation of human PDLFs.

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.52-59
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• 2006

This paper examined the conversion of methane to hydrogen and other higher hydrocarbons using dielectric barrier discharge with AC pulse power. Two metal electrodes of a coaxial-type plasma reactor were separated by gas gap and an alumina tube. The inner electrode was located inside the alumina tube. The alumina tube was located inside the stainless steel tube, which was used as the outer electrode. Effect of feed gas composition (methane, oxygen, argon, water and helium), flow rate, applied frequency, input volt-age on methane conversion and product distribution were studied. The major products of plasma chemical reactions were ethylene, ethane, propane, buthane, hydrogen, carbon monoxide and carbon dioxide. The increment of applied voltage and the usage of inert gas as the background (helium and argon) enhanced the selectivity of hydrocarbons and methane conversion. The addition of water in the feed stream enhanced the conversion of methane and yield of hydrogen. Higher voltage leads to higher yield of $C_2H_6,\;C_3H_8,\;C_4H_{10}$ and yield or $C_2H_2\;and\;C_2H_4$ appeared highly in lower voltage.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.3
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• pp.25-34
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• 2018

This paper presents a heating source of carbon nanofibers for the efficiency and the drying performance of laundry dryer, and focuses on the applicability-evaluation of its source. To design the proposed heating module, experiments were conducted in terms of surface temperature and surface temperature distribution characteristics of carbon nanofiber lamps. The surface temperature of the lamps increased linearly with increment of a current to flow a lamp and revealing the increasing pattern as the length of the ramps is shorter. The proposed heating source was evaluated based on drying efficiency, moisture evaporation rate at laundry, and internal temperature of a drum during drying process. The drying efficiency satisfied a 45% which is specified in KS C 9319. The moisture evaporation rate and the internal temperature of the drum were respectively 98.88% and $61.1^{\circ}C$, which are similar to that of S's company dryer. From the evaluation and actual drying test results, the proposed carbon nanofiber lamp heating module is considered to be applicable as a heat source for laundry dryer in terms of drying efficiency and drying performance. it is possible to obtain a heat source at a high temperature, an excellent calorific value, an improvement in drying performance, and an effect of sterilizing laundry due to the emission of far-infrared rays. In addition to the applicability, the difference of the drying efficiency between the dryers was analyzed in detail based on the power consumption of the heat sources.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.286-296
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• 2016

Offshore CCS technology is to transport and inject $CO_2$ which is captured from the power plant into the saline aquifer or depleted oil-gas fields. The more accumulated injected $CO_2$, the higher reservoir pressure increases. The increment of reservoir pressure make a dramatic change of the operating conditions of transport and injection systems. Therefore, it is necessary to carefully analyze the effect of operating condition variations over the injection period in early design phase. The objective of this study is to simulate and analyze the $CO_2$ behavior in the transport and injection systems over the injection period. The storage reservoir is assumed to be gas field in the East Sea continental shelf. The whole systems were consisted of subsea pipeline, riser, topside and wellbore. Modeling and numerical analysis were carried out using OLGA 2014.1. During the 10 years injection period, the change of temperature, pressure and phase of $CO_2$ in subsea pipelines, riser, topside and wellbore were carefully analyzed. Finally, some design guidelines about compressor at inlet of subsea pipeline, heat exchanger on topside and wellhead control were proposed.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.49-57
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• 2020

Due to the sewage sludge's characteristics of high water content and low calorific value, it is hard to use sewage sludge as an energy source. In this study, we investigated production of bio-solid fuel which is mixed both sewage sludge and woody biomass in order to improve the sewage sludge's characteristics and replace fossil fuels. A thermogravimetric analysis was used to investigate the co-combustion characteristics of the mixed coal and bio-solid fuel of 5%, 10%, 15%, respectively. The analysis was carried out under non-isothermal conditions by raising the internal temperature of 25℃ to 900℃ with an increment of 10℃/min. In the case of comparing single coal sample and mixture sample of coal and bio-solid fuel, the initiation combustion temperature has slightly changed. However, both the maximum combustion temperature and the termination start combustion temperature were hardly noticeable. The initiation combustion was occurred between 200~315℃ and the thermal decomposition causing a significant weight change occurred between 350~700℃. As a result of the kinetic analysis of the co-combustion, the activation energy was decreased as the mixing rate was higher. Therefore, it is able to co-combust the mixed coal and bio-solid fuel in power plants.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3448-3454
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• 2014

Generally existing structure analysis was applied to elastic analysis basically in practice. Considering the nonlinear material and the nonlinear geometric to be a more precise analysis, for this reason, The necessity for a structual analysis have been constantly required. Therefore, after optimization is performed, designed a simple model which is applied the principle of nonlinear in this study, a structural analysis of existing experienced users, have a aims at presenting theory and a method in order to perform anyone the analysis easily. In this study, the proposed model applied to die ribs, Regarding the shear load, less strain and stress was generated but strength was sufficient. The initial strain and stress was reconfigured to fit the size and shape, A hyperstudy in conjunction with Abaqus with nonlinear structural analysis, revealed an acceptable maximum and minimum range of stress and under the conditions of minimum strain, the plate made with a constant increment. In the experimental models, the plate thickness was given a power of 40 Newton, according to the thickness of the press die through an iterative process. When the stress and strain was applied to the die thickness, 7-8mm thickness could be obtained by optimizing.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.766-771
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• 1989

physicochemical properties of rice starch isolated from eight varieties were examined to evaluate the rice processing suitability The amylose contents of rice starch were varied with 16.7-29.7%, and IR 30, Godael, Aguja and Lengkwang varieties showed higher amylose content than the other varieties. The water binding capacity and blue value were in the range of 87.0 103.0 and 0.178-0.305, respectively. As the amylose content increased, the amylogram pasting temperature and the break down ratio increased, while the peak viscosity did not show any significant difference. The transmittance of 0.1% starch suspension slowly increased at $50^{\circ}C$ in the low-amylose content rice group, and rapidly increased at $65^{\circ}C$ in the high-amylose content rice group, but there were no differences above $75^{\circ}C$ among varieties. Also the low-amylose rice starch showed higher values in the swelling power and solubility. The hardness of the 30% rice starch gels was low in low-amylose one. During storage at $20^{\circ}C$ for 14 days, the increment of hardness was more slow in high-amylose one. The retrogradation velocity constant of rice starch gel by Avrami equation was the highest as 0.219 in Aguja variety.

• Journal of the Korean Chemical Society
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• v.38 no.8
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• pp.547-551
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• 1994

A series of samples in the $Nd_{1-x}Ba_xFeO_{3-y}$ system has been prepared by heating the reactants to$1200^{\circ}C$ under an ambient atmosphere, and the solid solutions were identified by X-ray power diffraction analysis. The crystal systems of samples with x = 0.00 and 0.25 were found to be orthorhombic whose local symmetry is similiar to the distorted octahedral with orthoferrite type one, whereas those with x = 0.50 and 0.75 to be the cubic system. Since Fe ions in the solid solutions are a mixed valence state between $Fe^{3+}\;and\;Fe^{4+}$ ions, the nonstoichiometric chemical formulas could be determined from the mole ratio of $Fe^{4+}$ ion and oxygen vacacies. According to the Mossbauer spectroscopic analysis, the presence of 5-coordinated $FeO_5$ was evidenced only in the barium compounds along with $FeO_6,\;and\;FeO_4$, but not in the strontium and calcium compounds. The samples with x = 0.25 and 0.50 show a spectrum of superparamagnetism, which might be due to the formation of a domain of the ferromagnetic interaction between the $Fe^{3+}\;and\;Fe^{4+}$ ions. The electrical conductivities of all samples are within semiconducting range. Since the $Fe^{4+}$ ion acts as an electron acceptor level during the electron transfer between the Fe through intermediate $O^{2-}$ ions, the activation energy of the compounds decreases with the increment of $Fe^{4+}$ content.