• Title/Summary/Keyword: Growth Deals

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Grain growth behavior of porous Al2O3 with addition of La2O3 prepared via freeze-casting (동결주조로 성형한 La2O3가 첨가된 Al2O3 다공체의 소결 중 입자성장 거동)

  • Kim, Sung-Hyun;Woo, Jong-Won;Jeon, Sang-Chae
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.32 no.6
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    • pp.231-238
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    • 2022
  • To secure the mechanical strength of porous Al2O3 ceramics, which can be utilized for filters and catalyst supports is essential for their functionality and durability. Superior mechanical strength would be obtained by tailoring the densification and grain growth during sintering. This study deals with grain growth behavior of a freeze-casted Al2O3 with addition of La2O3. In a temperature range between 1400 and 1600℃, variations of average grain size with sintering time and temperature were observed and analyzed with Gtn-G0n = kt and with k = k0exp(-Ea/RT). As a result, n value and activation energy (Ea) for grain growth were calculated as 3 and 489.09 kJ/mol, respectively. These commonly confirms retardation effect of the La addition during sintering of Al2O3 porous structure. More accurate analysis on the La effect can be followed to provide useful guidance for the selection of additives for better mechanical strength in Al2O3 porous structures.

Effect of Water Absorption on Fatigue Crack Growth Behavior of E-Glass/Polyerter Composite (E-Glass/Polyester 복합재료의 피로균열성장거동에 미치는 흡습의 영향)

  • Kim, Yon-Jig;Kweon, Il-Hyun;Lim, Jae-Kyoo;Jeong, Se-Hui
    • Korean Journal of Materials Research
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    • v.3 no.1
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    • pp.84-94
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    • 1993
  • This paper deals with the fatigue properties of chopped strand glass mat/polyester composite to understand the effect of water absorption on fatigue behavior of GFRP. The fatigue crack in the both no water and a water absorption materials initiated at the initial of cycle. Thereafter, it was divided with two regions that one decreased with the crack extension and the other increased with the crack extension. The absorption of distilled water degrades the bond strength between fiber and matrix, there, by the tendency of fiber pull-out is increased in perpendicular to crack growth deirection and the debonding of fibers increased to the place which is parallel to crack growth direction. Therefore, the reduction of fatigue strength was caused by these factors.

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Estimation of Population Ecological Characteristics of Small Yellow Croaker, Pseudosciaena polyactis off Korea (한국근해 참조기의 자원생태학적 특성치 추정)

  • ZHANG Chang-Ik;KIM Yong-Mun;YOO Sin-Jae;PARK Cha-Soo;KIM Su-Am;KIM Chong-Kwan;YOON Seong-Bong
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.25 no.1
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    • pp.29-36
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    • 1992
  • This paper deals with the estimation of population ecological parameters, including growth parameters, survival rates, instantaneous coefficient of natural mortality and age at first capture, of the small yellow-croaker, Pseudosciaena Polyactis in Korean waters, which determine fluctuations in stock abundance. For describing the growth of the small yellow croaker, von Bertalanffy growth equation was recommended for the purpose of stock assessment, although the Gompertz model yielded the closest fit. The survival rate (S) of the croaker was estimated to be 0.219 (variance=0.0000262), and the instantaneous coefficient of natural mortality (M) was 0.4 $year^{-1}$. From the estimates of S and M, the instantaneous coefficient of fishing mortality (F) was calculated to be 1.11$year^{-1}$ implying an impact from fishing three times that of natural mortality. Finally, the age at first capture $(t_{c})$ was estimated to be 0.602.

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A Study on the Trend and the Cultural Phenomenon of Mukbang (먹방의 유행과 문화현상 연구)

  • Cho, Eun-Ha
    • The Journal of the Korea Contents Association
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    • v.20 no.9
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    • pp.68-85
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    • 2020
  • Mukbang, which appeared through the new media platform in the early 2000s, reflected the life of the young generation who had to eat alone in the face of deteriorating socio-economic conditions. Many young people were able to watch Mukbang together, and gain comfort by establishing a virtual community of everyday life with those who suffered similar difficulties. Since then, Mukbang has evolved into various forms, reflecting the society and also accommodating the needs of viewers, and now it has become a global phenomenon, not just in Korea. Early research focuses on the phenomenon as a bizarre side that appears in the early stages rather than the growth and change of Mukbang, and deals with it in a limited way. This article critically examines these limitations, and examines how the growth and development of Mukbang interacted with the social change process, and how the uniqueness of Mukbang could emerge in the characteristics of the new media. Through this, we will be able to look at the context of the growth of Mukbang as a global phenomenon and the impact on the legacy media.

A Study on Succeeding Together-Busan New Port & BJFEZ (부산항 신항과 부산진해경제자유구역의 연계 발전 방안)

  • Song, Gye-Eui
    • Journal of Korea Port Economic Association
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    • v.28 no.1
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    • pp.123-142
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    • 2012
  • The purpose of this paper is to suggest a plan on succeeding together-Busan New Port & BJFEZ(that is, port hinterland development). This study deals with the terms of three connection growth factors which are a firm's subjective factors, a industrial environment factors, and a governmental policy factors. According to analysis results of the factors, a firm's subjective factors(4.11 score) are scored the most ones of connection growth factors of Busan New Port & BJFEZ, to be compared with a governmental policy factors(4.01 score). with a industrial environment factors(3.92 score). Therefore, first of all, Busan New Port & BJFEZ have to promote connection growth through as follows, a firm's subjective factors : (1) to procure competitiveness through establishment of connection growth model, (2) to promote concentrated marketing strategy & market response ability, (3) speedy meeting to customer's needs, (4) to procure reliability of Busan New Port & BJFEZ. And, the next, Busan New Port & BJFEZ have to promote connection growth through considering a governmental policy factors, a industrial environment factors.

On the Statistical Properties of the Parameters B and q in Creep Crack Growth Law, da/dt=B(C*)q, in the Case of Mod. 9Cr-1Mo Steel (Mod. 9Cr-1Mo강의 크리프 균열 성장 법칙의 파라메터 B와 q의 통계적 성질에 관한 연구)

  • Kim, Seon-Jin;Park, Jae-Young;Kim, Woo-Gon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.3
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    • pp.251-257
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    • 2011
  • This paper deals with the statistical properties of parameters B and q in the creep crack growth rate (CCGR) law, da/dt=B$(C^*)^q$, in Mod. 9Cr-1Mo (ASME Gr.91) steel which is considered a candidate materials for fabricating next generation nuclear reactors. The CCGR data were obtained by creep crack growth (CCG) tests performed on 1/2-inch compact tension (CT) specimens under an applied load of 5000N at a temperature of $600^{\circ}C$. The CCG behavior was analyzed statistically using the empirical equation between CCGR, da/dt and the creep fracture mechanics parameter, $C^*$. The B and q values were determined for each specimen by the least-squares fitting method. The probability distribution functions for B and q were investigated using normal, log-normal, and Weibull distributions. As far as this study is considered, it can be appeared that B and q followed the log-normal and Weibull distributions. Moreover, a strong positive linear correlation was found between B and q.

Changes in the Business Cycle of the Korean Economy: Evidence and Explanations (한국 경기변동의 특징 및 안정성에 대한 연구)

  • Lee, Jaejoon
    • KDI Journal of Economic Policy
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    • v.31 no.2
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    • pp.47-85
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    • 2009
  • With a relatively simple quantitative method, this study comprehensively analyzes the characteristics related to business cycles represented by macroeconomic variables of Korea since 1970. This empirical analysis deals with roughly following three topics: How to identify cyclical component with respect to trend; with what characteristics and how the economic variables of each sector move with in the phases of business cycle, and; whether there are signs of a structural change in the phases of business cycle. Section 2 discusses how to identify trends and cycle components, the basis assumption for the analysis of business cycle. Like the Korean economy, where a relatively high growth rate has been maintained, it is appropriate to determine its economic recession based on the fall in the growth trend, not in the absolute level of real output. And, it is necessary to apply the concept of growth cycle against a traditional concept of business cycle. Accordingly the setting of growth trend is of preliminary importance in identifying cyclical fluctuations. The analysis of Korea's GDP data since 1970, the decomposition of trends and cycles through the Band-pass filter is found to appropriately identify the actual phases of busyness cycle. Section 3 analyzes what particular relationship various economic variables have with output fluctuations during the phases of economic cycle, using the corss-correlation coefficients and prediction contribution. Section 4 monitors the stability of the phases of Korea's business cycle and quantitatively verifies whether there is a structural break, and then reviews the characteristics of variations in each sector. And, stylized facts observed through these studies are summarized in the conclusion. The macroeconomic stability of Korea, in particular, is found to continue to improve since 1970, except for the financial crisis period. Not only that, it is found that its volatility of economic growth rate as well as inflation have been reduced gradually. Meanwhile, until recently since 2000, the volatility in domestic demand has remained stable, while that in exports and imports has been increased slightly. But, in an over all perspective, Korea's business cycle variation is on the decline due to shorter response period to shocks and the formation of complementary relationship among economic sectors.

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A Study on Success Factors of Marine Special Economic Zone (해양경제특구의 성공 요인)

  • Song, Gye-Eui
    • Journal of Korea Port Economic Association
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    • v.31 no.1
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    • pp.51-68
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    • 2015
  • Recently, it has been emphasized that 'marine special economic zone' need to be designated and developed. Therefore, the purpose of this paper is to analyse on successful growth factors of 'marine special economic zone'. This study deals with the terms of three connection success factors which are a firm's subjective factors, a industrial environment factors, and a governmental policy factors. According to analysis results of the three successful growth factors, a firm's subjective factors(4.11 score) are scored at the most ones of the three successful growth factors, to be compared with a industrial environment factors(3.89 score). with a government policy factors(3.72 score). Therefore, first of all, it is important to enhance competitiveness of 'marine special economic zone' through as follows, a firm's subjective factors : (1) to procure concentrated market strategy and real market capacity, (2) to promote customer service, (3) to procure speedy satisfaction of customer needs and confidence, (4) to enhance competitiveness through standing in a trio of connection growth model. And, the next, we have to enhance competitiveness of 'marine special economic zone' through considering a industrial environment factors, that is, sustainable growth of marine industry, clustering of marine industry, expansion of infrastructure, etc., and a government policy factors, that is, leading law improvement and policy of leading 'marine special economic zone' designation and development, etc.,

Technological Progress and Job Creation (기술진보의 형태와 일자리창출)

  • Choi, Chang-Kon;Yi, Sun-Kyung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.1
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    • pp.181-187
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    • 2011
  • This paper deals with the job creation effect of economic growth by focusing on the types of technological progress. The hypothesis is that labor-saving technological change may create less job than capital-saving or factor-neutral ones. The hypothesis is proved theoretically using an equilibrium model of labor market. Empirically, first, a simulation experiment is performed to check the hypothesis empirically and confirms it. Secondly, we look at labor/capital ratio since it may be affected by the type of technological improvement. One important policy implication is that job creation effect of economic growth depends on the structure of labor supply as well as that of labor demand.

Crystal Growth Sensor Development of II-VI Compound Semiconductor : CdS (II-VI족 화합물 반도체의 결정성장 및 센서 개발에 관한 연구)

  • D.I. Yang;Y.J. Shin;S.Y. Lim;Y.D. Choi
    • Journal of the Korean Vacuum Society
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    • v.1 no.1
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    • pp.126-133
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    • 1992
  • This study deals with the crystal growth and the optical characteristics of CdS thin films activatedby silver. CdS:Ag thin films were deposited by using an electron beam evaporation(EBE) technique in vacuumof 1.5X 10-'torr, voltage of 4 kV, current of 2.5 mA and substrate temperature of 250$^{\circ}$C CdS:Ag photoconductivefilms prepared by EBE method show high photoconductivity after annealing at about 550"c for 0.5 h in air andAr gas.The grain size of CdS:Ag thin films annealed in Ar atmosphere (1 atm) was grown over 1 ym and the thicknessof the films is 4-5 pm. The analysis of X-ray diffraction patterns shows that the crystal structures are hexagonal.The diffraction line by (00.2) plane can only be observed, indicating that c-axis of hexagonal grows preferentiallyperpendicular to the substrate. The profiles of photoluminescence spectra of CdS:Ag films show Gaussian typecurves at room temperature, the maximum peak spectral sensitivity of CdS:Ag is located at the wavelength of520 nm.We annealed CdS:Ag thin films in air and Ar vapor in order to make the CdS photoconductors having theintensive photocurrent, the broad distribution of the photocurrent spectrum and the large value of the ratioof the photocurrent (pc) to the dark current(dc). We found that CdS:Ag thin films annealed in air atmospherewas the best one.air atmosphere was the best one.

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