The purpose of this study is to investigate experimentally the heat transfer characteristics of combustion gas or a mixture fuel of LFG and LNG as compared LFG, LNG A Pilot combustion system is constructed. Tube bundle type heat exchangers with vertical and horizontal baffles are used, and the experiment is carried out for different operating conditions, the heating value, the concentration of methane (44.5%, 54.5%). The results show that the Nusselt number of LNG is higher than that of LFG at the same Reynolds number, and in case LFG, the Nusselt number of the mixture of LFG and LNG is larger than that of LFG alone. Therefore, heat transfer is improved by using LFG that is added to LNG pertinently, if and instability of LFG supply will be relaxed.
Journal of the Korea Institute of Information and Communication Engineering
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v.19
no.5
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pp.1031-1039
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2015
This study examines the economic ripple effect on the domestic information security manufacturing and service sectors through input-output analysis. The production inducement coefficient of the manufacturing sector is bigger than the average of whole industry, but that of the service sector is smaller than the average. On the other hand, the service sector is superior to the manufacturing sector in the value added and employment inducement coefficients. Forward and backward linkage effects of manufacturing and service sectors are generally lower than those of the average of whole industry. The information security industry has insignificant contribution to national economy and employment growth overall. In particular, the manufacturing sector records minus contribution to employment growth, which means that a lot of effort for increasing employment must be given further on in the sector.
The effect of $Al_{2}O_{3}$ additives on the microstructure, mechanical and electrical properties of ${\beta}$-SiC+39vol.%$ZrB_2$ electroconductive ceramic composites by pressureless sintering were investigated. The ${\beta}$-SiC+39vol.%$ZrB_2$ ceramic composites were pressureless sintered by adding 4, 8, 12wt.% $Al_{2}O_{3}$ powder as a liquid forming additives at $1950^{\circ}C$ for 1h. Phase analysis of composites by XRD revealed mostly of $\alpha$-SiC(6H), $ZrB_2$ and weakly $\alpha$-SiC(4H), $\beta$-SiC(15R) phase. The relative density of composites was lowered by gaseous products of the result of reaction between $\beta$-SiC and $Al_{2}O_{3}$ therefore, porosity was increased with increased $Al_{2}O_{3}$ contents. The fracture toughness of composites was decreased with increased $Al_{2}O_{3}$ contents, and showed the maximum value of $1.4197MPa{\cdot}m^{1/2}$ for composite added with 4wt.% $Al_{2}O_{3}$ additives. The electrical resistivity of ${\beta}$-SiC+39vol.%$ZrB_2$ electroconductive ceramic composite was increased with increased $Al_{2}O_{3}$ contents, and showed positive temperature coefficient resistance (PTCR) in the temperature from $25^{\circ}C$ to $700^{\circ}C$.
Lee, Sang Hack;Park, Hyung Soo;Kim, Young-Jin;Kim, Won Ho;Sung, Jung Jong
Journal of The Korean Society of Grassland and Forage Science
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v.35
no.3
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pp.251-256
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2015
The study was conducted to determine greenhouse gas (GHG) inventories in grasslands. After 'Low Carbon Green Growth' was declared a national vision on 2008, Medium-term greenhouse gas reduction was anticipated for 30% reduction compared to Business As Usual (BAU) by 2020. To achieve the reduction targets and prepare to enforce emissions trading (2015), national GHG inventories were measured based on the 1996 Intergovernmental Panel on Climate Change Guidelines (IPCC GL). The national Inventory Report (NIR) of Korea is published every year. Grassland sector measurement was officially added in 2014. GHG removal of grassland soil was measured from 1990 to 2012. Grassland area data of Korea was used for farmland area data in the "Cadastral Statistical Annual Report (1976~2012)". Annual grassland area corresponding to the soil classification was used "Soil classification and commentary in Korea (2011)". Grassland area was divided into 'Grassland remaining Grassland' and 'Land converted to Grassland'. The accumulated variation coefficient was assumed to be the same without time series changes in grassland remaining grassland. Therefore, GHG removal of soil carbon was calculated as zero (0) in grassland remaining grassland. Since the grassland area increases constantly, the grassland soil sinks constantly . However, the land converted to grassland area continued to decrease and GHG removal of soil carbon was reduced. In 2012 (127.35Gg $CO_2$), this removal decreased by 76% compared to 1990 (535.71 Gg $CO_2$). GHG sinks are only grasslands and woodlands. The GHG removaled in grasslands was very small, accounting for 0.2% of the total. However, the study provides value by identifying grasslands as GHG sinks along with forests.
In batch bioreactor fermentations for cyclosporin A (CyA) production, good potential for bioprocess improvement was demonstrated in the immobilized cell system, providing appreciably better utilization of the catalytic activity of the biomass than the freely suspended cells, especially during the exponential phase. When concentrated nutrient medium was added pulsely during the exponential phase of cell growth(at hour 139 of fermentation), reactivation and regermination in both immobilized and suspended cell cultures were observed to contribute to the longevity of CyA production, maintaining maximum CyA titre until 250 hours of fermentation. Contrarily, simple batch fermentations without any supplement of medium in both systems showed repid decrease in CyA concentrations during the late stationary phase. Notably, the CyA yield coefficient $(Y_p/x)$ for the immobilized cell system was maintained quite high even after the pulse addition of the concentrated full medium, reaching almost 80% of the level attained during the exponential phase. This is in sharp contrast when compared with the corresponding value of 58% in the case of parallel-suspended cells. This pattern of CyA production resulted in considerably enhanced CyA production in the immobilized cell system, reaching almost 2 time higher maximum CyA production in comparison with the free cell system.
Kang Dong Shik;Jeon Jin Woo;Song Pung Keun;Kim Kwang Ho
Journal of the Korean institute of surface engineering
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v.38
no.3
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pp.95-99
/
2005
Quaternary Ti-Cr-Si-N coatings were synthesized onto steel substrates (SKD 11) using a hybrid method of arc ion plating (AIP) and sputtering techniques. For the Syntheses of Ti-Cr-Si-N coatings, the Ti-Cr-N coating process was performed substantially by a multi-cathodic AIP technique rising Cr and Ti targets, and Si was added by sputtering Si target during Ti-Cr-N deposition. In this work, comparative studies on microstructure and evaluation of mechanical properties between Ti-Cr-N and Ti-Cr-Si-N coatings were conducted. As the Si was incorporated into Ti-Cr-N coatings, the Ti-Cr-Si-N coatings showed largely increased hardness value of approximately 42 GPa than one of 28 GPa for Ti-Cr-N coatings. The average friction coefficient of Ti-Cr-N coatings largely decreased from 0.7 to 0.35 with increasing Si content up to 20 at. $\%$. In addition, wear behavior of Ti-Cr-N coatings against steel ball was much improved with Si addition due to the surface smoothening effect and tribe-chemical reaction.
International conference on construction engineering and project management
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2005.10a
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pp.968-973
/
2005
The purpose of this study is to clarify the reality of labor and capital productivity in the construction industry through an industry-level approach and to analyze the relationship between labor and capital productivity using a Cobb-Douglas production function. According to the research results, the construction industry has shown a very high capital productivity, while labor productivity has kept up a low level during the 1980s and 1990s. The reason was because of the lack of skillful construction workers and the decrease of capital. Meanwhile, the construction productivity has greatly increased since 2000 when there was no change in wages. This was because of a large inflow of low-wage foreign workers while the amount of value added has dramatically increased due to the liberalized sale price of apartment buildings. According to the analysis by the Cobb-Douglas production function, the elasticity coefficient of V/L to K/L in the construction industry had decreased from 1.1663 in the 1st period(1971-1988) to 0.4465 in the 2nd period(1989-1997), and to 0.1664 in the 3rd period(1998-2003). Such a result means that the allocation of labor has gradually increased while the allocation of capital has decreased. Moreover there was a big increase in allocation of labor after 1998 due to the excessive deterioration of capital. In conclusion, in order to raise the construction productivity and to avoid labor-intensive production methods, investment for capital should be more increased. In particular, new machinery and equipment that can actually substitute human labor in construction sites should be more developed and applied to construction sites.
The purpose of this paper is to analyze the effects of exports on Korea's employment and to decompose driving factors of change in Korea's employment embodied in exports (EEX). This study uses a multi-regional input-output (MRIO) and structural decomposition analysis (SDA) for empirical analysis, and uses a dataset of World Input-Output Tables (WIOTs) and Socio-Economic Accounts (SEAs) from the World Input-Output Database (WIOD). The main findings of the empirical results are summarized as follows. First, Korea's EEX continues to increase and Korea's share of EEX compared to total employment shows an upward trend. However, Korea's employment inducement coefficient of value-added exports showed a downward trend during the 2000-2014 period. Second, final demand from three countries (China, the United States, and the Rest of the World (RoW)) has affected a significant portion of Korea's EEX. Finally, from the results of the SDA, the effect of changes in final demand was the most important driving factor for the increase in Korea's EEX. Based on the results of this empirical analysis, this study discusses useful policy implications that could increase domestic employment in Korea.
Shin, Myung-Soo;Ki, Min Suk;Park, Beom Jin;Lee, Gyeong Joong;Lee, Yeong Yeon;Kim, Yeongseon;Lee, Sang Bong
Journal of Ocean Engineering and Technology
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v.34
no.5
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pp.294-303
/
2020
This study discusses data collection, calculation of wind and wave-induced resistance, and speed-power analysis of an 8,600 TEU container ship. Data acquisition system of the ship operator was improved to obtain the data necessary for the analysis, which was accomplished using SPA (Ship Performance Analysis, Park et al., 2019) in conformation with ISO15016:2015. From a previous operation profile of the container, the standard operating conditions of mean draft were 12.5 m and 13.6 m, which were defined with the mean stowage configuration of each condition. Model tests, including the load-variation test, were conducted to validate new ship performance and for the speed-power analysis. The major part of the added resistance of container ship is due to the wind. To check the reliability of wind-resistance calculation results, the resistance coefficients, added resistance, and speed-power analysis results using the Fujiwara regression formula (ISO15016:2015) and Computational fluid dynamics (Ryu et al., 2016; Jeon et al., 2017) analysis were compared. Wind speed and direction measured using an anemometer were used for wind-resistance calculation and the wave resistance was calculated using the wave-height and direction-data from weather information. Also, measured water temperature was used to calculate the increase in resistance owing to the deviation in water density. As a result, the SPA analysis using measured data and weather information was proved to be valid and able to identify the ship's resistance propulsion performance. Even with little difference in the air-resistance coefficient value, both methods provide sufficient accuracy for speed-power analysis. The differences were unnoticeable when the speed-power analysis results using each method were compared. Also, speed-power analysis results of the 8,600 TEU container ship in two draft conditions show acceptable trends when compared with the model test results and are also able to show power increase owing to hull fouling and aging. Thus, results of speed-power analysis of the existing 8,600 TEU container ship using the SPA program appropriately exhibit the characteristics of speed-power performance in deal conditions.
Journal of Korean Academy of Nursing Administration
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v.5
no.2
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pp.237-251
/
1999
The purpose of this study is to suggest successful strategies through which the effect of the information system of a hospital can be forecasted at the nursing department. In order to set up successful strategies, in the first place, both the methods of CSF(Critical Success Factor: Rockart, 1979) and ULD(User-Led Development) method and the method suggested by the Korea Productivity Center were applied. In order to measure the improvement of nursing productivity, the Dissonance theory was used. The data were collected from 100 employees serving at the clinic department of Kwangju Patriots' and Veterans' Hospital from July 4 to July 25, 1998 with reference to all 222 cases, for sampling work; then the part of the efficiency of the treatment or management of hospital business - simplification of the process of the treatment of hospital business and reduction of the time of the treatment of hospital business were measured; and in order to forecast organizational behavior, 100 cases of organization behavior were analysed, based on the well structured, questionnaires. In order to forecast the user's organizational behavior, a tool(Ronald. 1988; Stephen, 1982: Senn, 1992: Olsen, 1980: Anderson, 1988: Kim. 1992: Cho. 1994) to measure the extent or degree of the user's recognition or understanding whose reliability coefficient is 0.63 was used: and regarding the items expected by the users concerning the convenience of the system, a tool created by Bernadett, Szajna and Richard W. Scamell(1993) whose reliability coefficient is 0.88 was used. And finally, those data were analysed, utilizing the statistical package of SPSS/PC 6.0. successful strategies are suggested as follows: 1. In order that the Kwangju Patriots' and Veterans' Hospital's purpose can be successful through its strategic, information system, the quality of its services should be elevated. and for elevating the quality of medical services, elevation of the quality of medical expertism or specialty is an important factor in determining such quality. 2. In order to make the hospital information system to be successful, the hospital's top manager should participate in the effort making it successful with helping hands of the members or personnel of the hospital. 3. In order to make users participate in the hospital information system, it is prerequisite that all nurses in a hospital should voluntarily participate in the system 4. In order to reduce the expense, the time in coping with business per duty should be reduced by 10${\sim}$33.23%. The time of the direct nursing care which added value is relatively high should be elongated in order to elevate the quality of hospital services. 5. Since the introduction and spread of the hospital information system are influenced by the duration in the experience of computer use, the user of the hospital information system should have a plan to receive well-planned computer education. Finally it is suggested that the forecast of long-term productivity through a review of the user's expectation of the system should be inspected and tested through continuous studies of its effectiveness.
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