• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.63-64
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• 1993

레독스-흐름 2차전지는 발전소의 잉여전력, 태양전지 및 전기자동차 등 응용 분야가 넓은 유망한 에너지 저장 방법의 하나이다[1,2]. Fe-Cr계 2차전지와 비교하여 수소 가스의 발생이 없고 양쪽 액의 확산에의한 혼합으로 전지의 용량이 떨어지지 않고 rebalance의 필요가 없는 등 많은 장점을 가지고 있으며 조작이 간단하며 기전력 (1,4 V)과 에너지 밀도가 높기 때문에 compact화가 가능하다[1].

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.105-107
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• 2000

지금까지 국내외적으로 도심지역의 대기질 평가에 관한 연구로서 알데하이드의 분석은 상당히 많은 관심의 대상이 되어왔다. 광화학스모그의 전조물질로 널리 알려진 알데하이드는 대기중의 탄화수소가 광화학적으로 산화반응을 일으킬 때 형성되고 대기중의 라디칼의 주요 원천이며 유기 에어로졸 형성에도 크게 관여한다 대도시 지역에서는 공장굴뚝에서 방출되는 매연, 자동차의 배기가스가 알데하이드의 주요 인위적인 배출원으로 알려져 있다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.20-20
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• 1999

질산 암모늄(ammonium nitrate, AN)은 고체 추진제의 산화제로 사용하기에는 산소 함유량이나 밀도가 과산화염화 암모늄(ammonium perchlorate, AP)보다 불리하여 로켓 추진기관용으로는 널리 사용되지 않았지만 가스발생기용 추진제의 원료로 소량 사용되어 왔었다. 그러나 근래에 와서 군사 무기에 대한 안전 규정이 강화되면서 화재나 폭발에 대한 위험도를 낮추고, 특히 연소 기체에서 유독성 염화수소의 발생량을 줄이기 위해서는 AP나 RDX, HMX와 같은 산화제를 AN으로 대체 사용하는 연구를 많이 수행하고 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.829-835
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• 2010

This paper presents a disposable power generator for microfluidic devices; the power generator has a tubular PEMFC and a $H_2$ generator. The tubular PEMFC has a tubular MEA (diameter: 1.52 mm) that is supported by a spiral wire electrode. The $H_2$ generator supplied $H_2$ to the tubular PEMFC; $H_2$ was generated via the reaction of Al foil (27 mg) and 5 M NaOH (0.12 ml). The open circuit voltage and power density of a unit cell of the tubular PEMFC were 0.81 V and $16.4\;mW/cm^2$ (0.35 V), respectively. The $H_2$ generator generated 11.6 ml $H_2$ for 15min. The power generator was continuously operated for 15 min at 0.64 mW (0.71 V) and for 10 min at 1.06 mW (0.46 V). We experimentally verified that it is feasible to use the proposed power generator as a power source for microfluidic devices; in the experiment, an LED (2.5 mW; 1.8 V) was lit for 10 min by using three serially connected TPEMFCs and one $H_2$ generator.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.704-710
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• 2017

Although the desalination technique using gas hydrate formation is at a development stage compared to the commercially well-established reverse osmosis (RO), it still draws attention because of its simplicity and moderate operational conditions especially when using refrigerants for guest gases. In this study, DFT (density functional theory)-based molecular modeling was employed to explain the energetics of the gas hydrate formation using HFC (hydrofluorocarbon) and HCFC (hydrochlorofluorocarbon) refrigerants. For guest gases, R-134a, R-227ea, R-236fa, and R-141b were selected and three cavity structures ($5^{12}$, $5^{12}6^2$, and $5^{12}6^4$) composed of water molecules were constructed. The geometries of guest gas, cavity, and cavity encapsulating guest gas were optimized by molecular modeling respectively and their located energies were then used for the calculation of binding energy between the guest gas and cavity. Finally, the comparison of binding energies was used to propose which refrigerant is more favorable for the gas hydrate formation energetically. In conclusion, R-236fa was the best choice in terms of thermodynamic spontaneity, less toxicity, and low solubility in water.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.507-514
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• 2023

The selective catalytic reduction (SCR) of nitrogen oxides (NO_x) was investigated in a catalyst (Ag/γ-Al₂O₃) packed dielectric barrier discharge plasma reactor. The intermittent generation of plasma in the catalyst bed partially oxidized the hydrocarbon reductant for NO_x removal to several aldehydes. Compared to using the catalyst alone, higher NO_x conversion was observed with the intermittent generation of plasma due to the formation of highly reductive aldehydes. Under the same operating conditions (temperature: 250 ℃; C/N: 8), the NO_x reduction efficiencies were 47.5%, 92%, and 96% for n-heptane, propionaldehyde, and butyraldehyde, respectively, demonstrating the high NO_x reduction capability of aldehydes. To determine the optimal condition for intermittent plasma generation, the high voltage on/off cycle was adjusted from 0.5 to 3 min. The NO_x reduction performance was compared between continuous and intermittent plasma generation on the same energy density basis. The highest NO_x reduction efficiency was achieved at 2-min high voltage on/off intervals. The reason that the intermittent plasma discharge exhibited higher NO_x reduction efficiency even at the same energy density, compared to the continuous plasma generation case, is that the intermediate products, such as aldehydes generated from hydrocarbon, were more efficiently utilized for the reduction of nitrogen oxides.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.85-91
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• 2023

In this study, an experimental study was conducted on the flame behavior, combustion dynamics, and NOx emission characteristics for hydrogen co-firing with the EV burner which is the first stage combustor of GT24. It was confirmed that as the hydrogen co-firing rate increases, the NOx emission increases. This change was elucidate to be the result of a combination of changes in penetration depth due to changes in fuel density, reduction in fuel mixing due to changes in flame position due to increased flame propagation speed, and oscillation of fuel mixedness due to combustion instability. Through pressurization tests in the range of 1.3 to 3.1 bar, NOx emission characteristics under high-pressure operating conditions were predicted, and based on this, the hydrogen co-firing limits of the EV burner was evaluated.

• Journal of Wetlands Research
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• v.10 no.3
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• pp.9-26
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• 2008

To clarify the reed (Phragmites australis) stand's effects on the sediment properties and its increasing pattern, breaths of reed stands in 1999 and 2000, and sediment properties - water, salt, organic matter, sulphur, nitrogen, carbon and hydrogen contents - along th depth at the three stands in 2007 were surveyed at Suncheon Bay. Regardless of reed stand, the more distance from the land was long, the more water and salt contents of sediment were high. Organic matter content of sediment was high and increased with the reed biomass at the upper layer but low regardless of biomass at the lower layer. Sulphur content of sediment was higher at old reed stand (0.33%) than at new stand (0.21%) or non-vegetated stand (0.23%). Carbon, nitrogen and hydrogen contents of sediment were similar at three stands in mean values. However, their contents were high at upper layer and low at lower layer in a stand. Therefore, the changing pattern of organic matter content with the depth was similar to but not coincided to the inorganic nutrients' ones. The mean breadth of reed stands increased $2.33{\pm}0.73m$ in 1999 and $3.65{\pm}1.64m$ in 2000. However, the increase of reed stands' breadth a year varied along the direction, year or stands, so that there was not a trend in increasing pattern. It was thought that this increasing pattern made the reed's patch round. The height and density of reed shoot in newly formed stand decreased with the distance from the center of stand. In the newly formed peripheral area of a reed stand, the shoot density was not related with the land (north) or sea (south) direction, however, the shoot height was higher in the sea (south) than in the land (north) direction.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.438-445
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• 1997

${\beta}-PbO_2$ electrode, which was electrodeposited on Ti madras, was prepared and for the decomposition of cyanide in electroplating wastewater. After the investigation of temperature and pH conditions for no hydrogen cyanide evolution during the decomposition of cyanide, the optimum current densities of ${\beta}-PbO_2$ electrodeposition and cyanide decomposition were determined in 500ppm NaCN solution, and durability of ${\beta}-PbO_2$ electrode was also investigated. Hydrogen cyanide was actively generated above $40^{\circ}C$ and was not evolved above pH 13. ${\beta}-PbO_2$ electrode electodeposited at $5A/dm^2$ showed the best cyanide decomposition efficiency The decompostion efficiency was about 70% at low decomposition current density ($0.08A/dm^2$), and it decreased gradually to about 10% as the decomposition current density increased up to $4A/dm^2$. The film of ${\beta}-PbO_2$ electrodeposited was corrosive at $20A/dm^2$ and was broken at $50A/dm^2$.

• Journal of Energy Engineering
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• v.18 no.1
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• pp.56-62
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• 2009

With weld metal of X65 steel, hydrogen was charged by electro-chemical method and mechanical behavior such as strength was measured by the small punch test. The weld metal was more sensitive to hydrogen charging than the case of base metal. The small punch (SP) strength was decreased as the hydrogen contents increased. Magnitude of strength decrease was dependent on current density, temperature, charging time. Current density and charging time have significant effect on the mechanical properties but temperature of electrolyte has limited effect. Fractured surfaces of the tested specimens were observed by SEM (scanning electron microscope). In the hydrogen charged specimens cleavage fracture were observed, which is consistent with the SP test results. Since the testing procedure for studying hydrogen embrittlement proposed in this study has shown good reproducibility of test results, the proposed method can be assumed to be a reliable test procedure. Using the electrochemical charging and the small punch test, the change of SP strength for X65 weld metal due to hydrogen embritlement could be evaluated sensitively.