• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.389-396
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• 2002

In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.

• Nuclear Engineering and Technology
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• v.12 no.3
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• pp.163-170
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• 1980

A Mather type plasms gun is operated at below 1 torr with a energy storage system (4KJ, 16.5KV, 35nH) to study the conditions of the efficient plasma focus. When the $D_2$ gas filling pressure is 0.18 torr and the stored energy is 3.8KJ, the discharge current of max. 180KA is obtained and the average axial velocity of the plasma is about $7cm/\mu\textrm{s}$. This is lower than the calculated velocity with above conditions by the snow-plow model. The discrepancy is due to the currents flowing over the insulator surface. The plasma focus occurs at low pressure compared with the results obtained by Bruzzone. The reasons are such that the plasma gun employed in this experiment is large for tile stored energy and the concentration of the residual gas is comparatively high. It is confirmed by a Long counter that the neutrons are generated from the dense plasma focus.

• Carbon letters
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• v.9 no.4
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• pp.303-307
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• 2008

The studies on integrated operation of fuel cell with fuel processor are very essential prior to its commercialization. In this study, Polymer Electrolyte Membrane Fuel Cell (PEMFC) was operated with a fuel processor, which is mainly composed of two parts, methanol steam reforming reaction and preferential oxidation (PROX). In fuel processor, ICI 33-5 (CuO 50%, ZnO 33%, $Al_2O_3$ 8%, BET surface area: $66\;m^2g^{-1}$) catalyst and CuO-$CeO_2$ catalyst were used for methanol steam reforming, preferential oxidation (PROX) respectively. PEMFC was operated by hydrogen fuel generated from fuel processor. The resulting gas from PROX reactor is used to operate PEMFC equipped with our prepared anode and cathode catalyst. PtRu/C catalyst gives more tolerance to CO.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.413-416
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• 2006

The power source of an AC-PDP fur sustainer circuit is operated in high-voltage and high frequency switching during the process required to achieve the gas discharge current to generate light in a PDP panel. Since PDP has the characteristics of a pure capacitive load, the displacement current that occurs during charge and discharge generates considerable reactive power. An auxiliary circuitry called Energy Recovery Circuit (ERC) reduces the capacitive displacement current. However, this auxiliary topology also bears high stress in its components. In this paper, a multilevel voltage wave shaping sustainer circuit with auxiliary ERC characteristics for an AC-PDP driver is proposed. A comparative analysis and experimental results are presented.

• Journal of Microbiology and Biotechnology
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• v.6 no.1
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• pp.30-35
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• 1996

Distillery wastewater was used in a thermophilic laboratory-scale two stage anaerobic digester to test the effects of the redox potential of the first acidogenic reactor on the performance of the system. The digester consisted of first a acidogenic reactor and the an upflow anaerobic sludge blanket (UASB) reactor. The digestor was operated at a hydraulic retention time (HRT) of 48 h. Under these conditions, about 90% of the chemical oxygen demand as measured by the chromate method ($COD_{cr}$) was removed with a gas production yield of 0.4 l/g-COD removed. The redox potential of the acidogenic reactor was increased when the reactor was purged with nitrogen gas or agitation speed was increased. The increase in reduction potential was accompanied by an increase in acetate production and a decrease in butyrate formation. A similar trend was observed when a small amount of air was introduced into the acidogenic reactor. It is believed that the hydrogen partial pressure in the acidogenic reactor was decreased by the above mentioned treatments. The possible failure of anaerobic digestion processes due to over-loading could be avoided by the above mentioned treatments.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.96-102
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• 2008

As LNG tank is operated around $-162^{\circ}C$, an experimental approach on the cryogenic temperature tensile and fatigue strengths of SUS304L lap joint weld is very important at the design stage of membrane type LNG tank. In this study, in order to estimate the tensile and fatigue strengths of SUS304L lap joint weld at cryogenic temperature condition, tensile and fatigue tests were conducted. Also, S-N curves are presented with statistical testing method recommended by JSME. As a result of the experimental approach, the d￡sign guide of fatigue strength is proposed and that is expected to be useful for membrane type LNG tank design.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.236-241
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• 2013

It requires long time and high cost for an apprentice engineer to reach the level of getting various experiences of engine space machinery and preparing for emergency situations. Therefore reducing the time and cost, several types of simulator that give the very similar surroundings to the ship engine room, relevant to STCW-95 are used for systematic education and training to get many experiences and good judgement in emergency. Since most simulators that are operated in Korea were imported from foreign countries, it is difficult to directly implant the amendments of STCW Convention and reflect International Maritime Organization (IMO) model courses. This study describe a development of marine auxiliary boiler simulator that makes the apprentice engineer easier to understand the relationship between equipments in steam system such as auxiliary boiler, exhaust gas boiler, and steam turbine.

• Journal of Ocean Engineering and Technology
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• v.32 no.4
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• pp.279-286
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• 2018

The use of eco-friendly energy in the offshore plant system is expanding because conventional generators are operated by fossil fuel or natural gas. Eco-friendly energy, which replaces existing power generation methods, should be capable of generating the power for lighting protection equipment, airborne fault indication, parameter measurement, and others. Most of the eco-friendly energy used in offshore plant facilities is solar and wind power. In the case of using photovoltaic power, because the structure must be constructed based as flat solar panels, it can be damaged easily by the wind. Therefore, there is a need for a new generation system composed of a spherical structure that does not require a separate structure and is less influenced by the wind. Considering these characteristics, in this study we designed, fabricated, and tested a unit that could provide the most efficient spherical photovoltaic power generation considering wind direction and wind pressure. Our test results indicated that the proposed system reduced costs because it did not require any separate structure, used eco-friendly energy, reduced carbon dioxide emissions, and expanded the proportion of eco-friendly energy use by offshore plant facilities.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.73-79
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• 2017

BACKGROUND: Carbonized biomass is a carbon-rich solid product obtained by the pyrolysis of biomass. It has been suggested to mitigate climate change through increased carbon storage and reduction of greenhouse gas emission. The objective of this study was to evaluate carbon dioxide ($CO_2$) and nitrous oxide ($N_2O$) emissions from soil after carbonized biomass addition. METHODS AND RESULTS: The carbonized biomass was made from a pyrolyzer, which a reactor was operated about $400{\sim}500^{\circ}C$ for 5 hours. The treatments were consisted of a control without input of carbonized biomass and two levels of carbonized biomass inputs as 6.06 Mg/ha for CB-1 and 12.12 Mg/ha for CB-2. Emissions of $CO_2$ and $N_2O$ from orchard soil were determined using closed chamber for 13 weeks at $25^{\circ}C$ of incubation temperature. It was shown that the cumulative $CO_2$ were $209.4g\;CO_2/m^2$ for CB-1, $206.4g\;CO_2/m^2$ for CB-2 and $214.5g\;CO_2/m^2$ for the control after experimental periods. The cumulative $CO_2$ emission was similar in carbonized biomass input treatment compared to the control. It was appeared that cumulative $N_2O$ emissions were $4,478mg\;N_2O/m^2$ for control, $3,227mg\;N_2O/m^2$ for CB-1 and$ 2,324mg\;N_2O/m^2$ for CB-2 at the end of experiment. Cumulative $N_2O$ emission contents significantly decreased with increasing the carbonized biomass input. CONCLUSION: Consequently the carbonized biomass from byproducts such as pear branch residue could suppress the soil $N_2O$ emission. The results fromthe study imply that carbonized biomass can be utilized to reduce greenhouse gas emission from the orchard field.

• Journal of Gastric Cancer
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• v.8 no.1
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• pp.27-34
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• 2008

Purpose: Many recent studies have reported on the feasibility and usefulness of laparoscopy assisted distal gastrectomy (LADG) for treating early gastric cancer. On the other hand, there has been few reports about laparoscopy assisted total gastrectomy (LATG) because upper located gastric cancer is relatively rare and the surgical technique is more difficult than that for LADG, We now present our procedure and results of performing LATG for the gastric cancer located in the upper or middle portion of the stomach. Materials and Methods: From Jan 2005 to Sep 2007, 96 patients underwent LATG by four surgeons at the Asan Medical Center, Seoul, Korea. Among them, 48 consecutive patients who were operated on by asingle surgeon were analyzed with respect to the clinicopathological features, the surgical results and the postoperative courses with using the prospectively collected laparoscopy surgery data. Results: There was no conversion to open surgery during LATG. For all the reconstructions, Roux-en Y esophago-jejunostomy and D1+beta lymphadenectomy were the standard procedures. The mean operation time was $212{\pm}67$ minutes. The mean total number of retrieved lymph nodes was $28.9{\pm}10.54$ (range: $12{\sim}64$) and all the patients had a clear proximal resection margin in their final pathologic reports. The mean time to passing gas, first oral feeding and discharge from the hospital was 2.98, 3.67 and 7.08 days, respectively. There were 5 surgical complications and 2 non-surgical complications for 5 (10.4%) patients, and there was no mortality. None of the patients needed operation because of complications and they recovered with conservative treatments. The mean operation time remained constant after 20 cases and so a learning curve was present. The morbidity rate was not different between the two periods, but the postoperative course was significantly better after the learning curve. Analysis of the factors contributing to the postoperative morbidity, with using logistic regression analysis, showed that the 8MI is the only contributing factor forpostoperative complications (P=0.029, HR=2.513, 95% CI=1.097-5.755). Conclusions: LATG with regional lymph node dissection for upper and middle early gastric cancer is considered to be a safe, feasible method that showed an excellent postoperative course and acceptable morbidity. BMI should be considered in the patient selection at the beginning period because of the impact of the BMI on the postoperative morbidity.