• Journal of the Society of Naval Architects of Korea
• /
• v.46 no.4
• /
• pp.444-451
• /
• 2009

The price increase of natural resources and the worldwide growth of LNG demand led to save the waste of Boil-Off Gas evaporating from cargo tanks of LNG carriers during navigation. As one of the efforts, a BOG reliquefaction system with BOG-to-BOG heat exchanging method was newly devised. This study was also discussed on the process details such as some features and advantages including comparisons with conventional BOG reliquefaction system, non BOG-BOG heat exchange type. The thermodynamic analysis for the system were also performed. Through the cycle simulation, the process efficiency of the BOG reliquefaction system BOG-BOG heat exchange was estimated to be increased up to 21%.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.1
• /
• pp.599-608
• /
• 2021

The oil and gas industry is widely known as a vital engine of Vietnam development, stimulating researchers to examine the association of various factors with this industry. The aim of this study is to identify the relationship between different variables affecting profitability of the firms in the oil and gas sector in Vietnam. The total of 203 samples were collected from 29 companies listed on Vietnam Stock Market during a 6-year period from 2012 to 2018. Informed by prior research, this investigation employs financial leverage (FL), government ownership (GOV), dividend payout (DIV), fixed assets to total assets (FA) and exchange rate (EXR) as independent variables, while the profit is described by return-on-assets (ROA). The study results show that there are four factors that have an impact on ROA, namely, leverage, government ownership, dividend, and exchange rate. Whereas leverage and exchange rate have negative influence on ROA, government ownership and dividend payment have a positive effect. The findings of this study suggest that high debt ratio in capital structure and the negative effect of exchange rate on their companies' efficiency can adversely affect the profit of enterprises. Also, plausible extent of government ownership and dividend payment could also be considered to optimize corporate performance.

• The Korean Journal of Physiology
• /
• v.1 no.1
• /
• pp.73-76
• /
• 1967

A nomogram of gas exchange ratio (R) in air breathing subjects ,was porposed which enables a simple and rapid determination of R value using the fractional concentrations of nitrogen and carbon dioxide in the expired or alveolar gas. The readable limit of R value seems less than 1/100 of R unit and the average difference between the values from the nomogram and the actually calculated values is less than 0.005 of R unit. The usefulness of this nomogram for rapid and frequent determinations of the oxygen uptake is also suggested.

• Journal of the Korean Magnetics Society
• /
• v.11 no.4
• /
• pp.146-150
• /
• 2001

The effect of H$_2$ content in Ar sputtering gas on exchange coupling field(H$_{ex}$) for NiFe/FeMn interface was studied. When NiFe layer of Si(100)/Ta(50 $\AA$)/NiFe(60 $\AA$)/FeMn(250 $\AA$)Ta(50 $\AA$) was deposited at 8% H$_2$ in sputtering gas, the maximum exchange coupling field(H$_{ex}$) and minimum coercivity(H$_{c}$) were obtained. When Si(100)/Ta(50 $\AA$)/NiFe(60 $\AA$)/FeMn(250 $\AA$)/NiFe(70 $\AA$)/Ta(50 $\AA$) was deposited at 5% H$_2$ in sputtering gas, the maximum exchange coupling field(H$_{ex}$) of 148 Oe was obtained. The (111) preferred orientation and grain size of underlayer NiFe were increased and the internal stress was reduced by H$_2$ in sputtering gas. And the (111) preferred orientation and grain size of FeMn layer were also increased.d.ased.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.60-60
• /
• 2017

It is important to measure the gas exchange activity of the crops in canopy scale to understand the process of biomass production and yield formation. Thermal imaging of the canopy surface temperature is a powerful tool to detect the gas exchange activity of the crop canopy. The simultaneous measurement of the canopy temperature and the meteorological data enables us to calculate the canopy diffusive conductance ($g_c$) based on the heat flux model (Monteith et al. 1973, Horie et al. 2006). It is, however, difficult to realize the long-term and continuous monitoring of $g_c$ due to the occurrence of the calculation error caused by the fluctuation of the environmental condition. This is partly because the model assumption is too simple to describe the meteorological and aerodynamic conditions of the crop canopy in the field condition. Here we report the novel method of the direct measurement of the aerodynamic resistance ($r_a$) of the crop canopy, which enables us the stable and continuous measurement of the gas exchange capacity of the crop plants. The modified heat balance model shows the improved performance to quantify $g_c$ under the fluctuating meteorological condition in the field. The relationship between $g_c$ and biomass production of rice and soybean varieties is also discussed in the presentation.

• Journal of the Korean Institute of Gas
• /
• v.3 no.2 s.7
• /
• pp.11-16
• /
• 1999

Oil and LNG products are characterized by the facts that the raw materials are all imported and financing is dependent heavily upon foreign countries. This makes the oil and LNG products sensitive to changes in foreign exchange rates. However, the extent to which they respond to changes in foreign exchange rates, particularly the extent of price changes, vary considerably, due to the differences in the structures of price determination. The purposes of this paper are twofolds. The first one is to analyze the structures of price determination of diesel, heavy oil, and LNG. The second one is to analyze the effects of changes in foreign exchange rates on the prices of and price competitiveness of the fuels in question through the sensitivity analysis. The results of the sensitivity analysis indicate that diesel price is most sensitive and heavy oil price is least sensitive to changes in foreign exchange rates.

• Journal of the Korean Institute of Gas
• /
• v.11 no.1 s.34
• /
• pp.51-54
• /
• 2007

78-cell proton exchange membrane fuel cell(PEMFC) stack with an effective electrode area of $295cm^{2}$ were investigated its operational characteristics and effects of CO poisoning. When power output, 5.4 kW, was released at current density of $325mA/cm^{2}$ for 6 hours, stablility of each cell was showed the small deviation of 2.3%. Carbon monoxide is a conventional contaminant in the fuel obtained from reforming processes with an important influence on the performance of the PEMFC. The studies of continuous injection of CO presented (5-20 ppm) with the time gave information about poisoning and recovery processes of the stack.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.99-104
• /
• 2007

Tracer gas technique is widely used to measure the ventilation rates and/or ventilation effectiveness of building spaces. However, the conventional method using a single tracer gas can measure only outdoor air change rates in a single zone. This paper deals with the multi-gas tracer technique to measure air exchange rates between rooms. Interzonal air movements are important to characterize overall ventilation performance of complicated multi-zone buildings. Experiments are conducted in a simple two-room model with known airflow rates using tracer gases of SF6 and R134a. The concentration decays of two tracer gases are measured after simultaneous injections in each room. The governing equations are derived from the continuity and the mass balance of each room. The data reduction procedure are developed to obtain the inter-room airflow rates using the governing matrix inversion, and various data manipulation methods are tested, such as data shift, interpolation, smoothing, and etc, to improve the estimate and interpretation of the results.

• The Korean Journal of Ecology
• /
• v.22 no.2
• /
• pp.79-83
• /
• 1999

Phytotoxic effects of ozone and ethylenediurea (EDU) on soybean (Glycine max) and spinach (Spinacia oleracea) were observed by using open-top field chamber system (OTC). Gas exchange rates (photosynthesis. stomatal conductance and transpiration rates) of soybean plants were decreased by 20% to 30% by ambient ozone and resulted in 30% reduction of seed yields. In OTC. ambient ozone and 0.12 $\mu$l/l $O_3$ decreased gas exchange rates of spinach by 25% to 40% and by 50%. respectively. The protective effect of EDU against ozone induced injury was obtained at 100 mg/l on soybean. and at 250 mg/l on spinach, respectively. The excessive application of EDU. however. inhibited photosynthesis. transpiration. and stomatal conductance without any specific visible damage.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.2 no.4
• /
• pp.112-119
• /
• 1994

This study is investigated into the dynamic effect of the manifold configuration during the gas exchange processes using both simulation and experiment, In theoretical study on the flow analysis, the characteristic method is applied to solve the compressible unsteady flow equation, involving the several steady flow boundary conditions. In order to excute the engine experiment efficiently, a data acquisition system is configured by using A/D converter and PC. Good results which coincided experimental data with simulation output were obtained, and it shows that this simulation method can be applied to obtain the optimal design parameters in the intake and exhaust systems.