• 대한기계학회논문집B
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• 제29권11호
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• pp.1277-1284
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• 2005

The combustion characteristics of methane oxygen diffusion flames have been investigated to give basic information for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since the small amount of nitrogen is included from the current low cost oxygen production process. Flame lengths decreased with increasing fuel or oxygen velocity because of the enhancement of mixing effect. Correlation equation between flame length and turbulent kinetic energy was proposed. NOx concentration was reduced with increasing fuel or oxygen velocity because of the enhanced entrainment of the product gas into flame zone as well as the reduction of residence time in combustion zone.

• 한국주조공학회지
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• 제26권1호
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• pp.27-33
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• 2006

Phase evolutions involving nucleation stages together with diffusional growth have been examined in order to provide a guideline for determining rate limiting stages during phase evolutions. In multiphase materials systems in coatings, composites or multilayered structures, diffusion treatments often result in the development of metastable/intermediate phases at the reaction interfaces. The development of metastable phases during solid state interdiffusion demonstrates that the nucleation reaction can be one controlling factor. Also, the concentration gradient and the relative magnitudes of the component diffusivities provide a basis for a phase selection and the application of a kinetic bias strategy in the phase selection. For multicomponent alloy systems, the identification of the operative diffusion pathway is central to control phase formation. Experimental access to the nucleation and growth stage is discussed in thin film multi layers and bulk samples.

• 한국경영과학회지
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• 제28권2호
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• pp.61-74
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• 2003

Many firms try to enhance the customer satisfaction, because they believe that higher customer satisfaction leads to superior returns. According to expectancy disconfirmation model, consumers judge the satisfaction in comparison with their expectations about the product performance. If the performance is above the expectations, increase in satisfaction is expected. If the performance is below the expectations, decrease in satisfaction is expected. This explanation contradicts our beliefs that higher expectation leads to consumer's choices. To address the contradiction, this paper present a unified model which combines the expectancy disconfirmation model with the well-known diffusion model. The unified model shows that the expectation can increase the choices even if the expectation decreases the satisfaction.

• 한국연소학회지
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• 제16권2호
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• pp.40-46
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• 2011

The diesel pre-heater has being used in cabin heating and coolant heating of engine to reduce the engine warm up time for commercial vehicle. The pre-heaters are classified as diesel spray combustor and it forms diffusion flame. By using swirler, a recirculation flow of hot product gases is established near the fuel nozzle and it helps the maintaining of diffusion flame. The design difference of swirler can affect on reaction characteristics and temperature distribution inside pre-heater. The purpose of this study is the investigation of the effect of swirler configuration on combustion characteristics. To solve spray combustion problem, the Euler-Lagrange approach discrete model is used to track droplet trajectory and evaporation history. The PDF equilibrium model is used for chemical reaction model. These models are implemented into the FLUENT code.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.849-853
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• 2018

Mechanistic calculations for wet scrubbing of aerosol/vapor from gas bubble rising in liquid pool are essential to safety of sodium-cooled fast reactor. Hence, scrubbing of volatile fission product from mixed gas bubble rising in sodium pool is presented in this study. To understand this phenomenon, a theoretical model has been setup based on classical theories of aerosol/vapor removal from bubble rising through liquid pools. The model simulates pool scrubbing of sodium iodide aerosol and cesium vapor from a rising mixed gas bubble containing xenon as the inert species. The scrubbing of aerosol and vapor are modeled based on deposition mechanisms and Fick's law of diffusion, respectively. Studies were performed to determine the effect of various key parameters on wet scrubbing. It is observed that for higher vapor diffusion coefficient in gas bubble, the scrubbing efficiency is higher. For aerosols, the cut-off size above which the scrubbing efficiency becomes significant was also determined. The study evaluates the retention capability of liquid sodium used in sodium-cooled fast reactor for its safe operation.

• International Journal of Internet, Broadcasting and Communication
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• 제15권4호
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• pp.279-293
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• 2023

This study investigates network effects to measure how strongly the early adopters affect the brand choice of the potential consumer. By using the Gumbel-Hougaard (GH) copula, this study checks the magnitude of network effects varied from country to country. To consider consumer heterogeneity and network effects in the growth market, this study proposes the multi-brand Gamma/Shifted-Gompertz (m-G/SG) model based on the GH copula. Out of eighteen Western European cellular phone market data and South Korea smartphone data sets, the m-G/SG model provides an improvement in the estimation accuracy over the Libai, Muller, and Peres model. The results show that network effects enhance (i) the polarization of brand choice probabilities as time elapses; (ii) the dominance of the more preferred and the earlier entered brand; and (iii) the deceleration of category-level diffusion. Potential followers can analyze their relationship with earlier entrants through the m-G/SG model and also establish an optimal market entry strategy.

• Journal of Korea Trade
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• 제23권2호
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• pp.14-33
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• 2019

Purpose - This paper aims to articulate determinants of inter-organizational cooperation based on to the extent to which inter-organizational tasks are related to product development and production processes. Design/Methodology - This research conducted OLS regression analysis based on the data acquired from questionnaire survey in Korean auto industry. Findings - Our analysis has verified that complementary and compatible resources, as well as physical and human asset specificities, positively affect inter-organizational product development cooperation. Conversely, in the production process, only complementary resources positively affect inter-organizational cooperation, whereas compatible resources and physical asset specificity have a negative influence. The changing characteristics of compatible resources (with IT innovations and AI), and physical asset specificity (influenced by a rising need to reduce production costs), cause inter-organizational cooperation in production to decrease. Originality/value - This research attempts to expound upon these determining factors of inter-organizational cooperation by considering both complementary-compatible resources and asset specificity in product development and production simultaneously. The reason why the impact of complementary-compatible resources and asset specificity on inter-organizational cooperation is critical in understanding the determinants of inter-organizational cooperation is that the attributes of complementary-compatible resources and asset specificity in production have changed drastically due to the continuing diffusion of IT innovations and AI (Artificial Intelligence).

• 한국분말재료학회지
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• 제20권3호
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• pp.197-202
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• 2013

A novel route to prepare Nd-Fe-B magnetic particles by utilizing both spray drying and reduction/diffusion processes was investigated in this study. Precursors were prepared by spray drying method using the aqueous solutions containing Nd salt, Fe salt and boric acid with stoichiometric ratios. Precursor particles could be obtained with various sizes from 2 to $10{\mu}m$ by controlling concentrations of the solutions and the average size of $2{\mu}m$ of precursors were selected for further steps. After heat treatment of precursors in air, Nd and Fe oxides were formed through desalting procedure, followed by reduction processes in Hydrogen ($H_2$) atmosphere and with Calcium (Ca) granules in Argon (Ar) successively. Moreover, diffusion between Nd and Fe occurred during Ca reduction and $Nd_2Fe_{14}B$ particles were formed. With Ca amount added to particles after $H_2$ reduction, intrinsic coercivity was changed from 1 to 10 kOe. In order to remove and leach CaO and residual Ca, de-ionized water and dilute acid were used. Acidic solutions were more effective to eliminate impurities, but Fe and Nd were dissolved out from the particles. Finally, $Nd_2Fe_{14}B$ magnetic particles were synthesized after washing in de-ionized water with a mean size of $2{\mu}m$ and their maximum energy product showed 9.23 MGOe.

• 디지털융복합연구
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• 제17권8호
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• pp.149-157
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• 2019

본 연구는 스마트 스피커의 사용-확산을 결정할 수 있는 다양한 요인을 제안하고 이러한 요인들이 소비자 사용-확산에 미치는 영향을 분석하고자 하였다. 스마트 스피커를 사용해 본 경험이 있는 중국 소비자 262명의 설문조사 데이터를 수집하여 구조방정식 모형을 이용하여 분석하였다. 연구결과 스마트 스피커의 자동성과 적응성 모두 지각된 유용성과 지각된 용이성에 유의한 영향을 미치는 것으로 나타났다. 다기능성과 호환성은 지각된 유용성에 영향을 미치는 반면 반응성은 지각된 유용성과 지각된 용이성에 영향을 미치지 않았다. 의인화는 지각된 유희성에 영향을 미치는 것으로 나타났다. 지각된 유용성과 지각된 용이성은 모두 사용 다양성과 사용량을 향상시키고 지각된 유희성은 사용 다양성에 영향을 주었다. 본 연구는 이러한 결과들을 통하여 스마트 제품의 디자인 및 마케팅 커뮤니케이션을 위하여 소비자들에 대해 고려해야 하는 요소들을 이해하는데 도움을 줄 것으로 기대한다.

• 한국건설순환자원학회논문집
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• 제10권4호
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• pp.600-608
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• 2022

이 연구는 전기영동확산시험을 이용하여 이중층수산화물(LDH)을 혼입한 균열이 있는 자기치유 시멘트 모르타르의 염화물 침투 저항성을 평가하여 LDH가 자기치유 콘크리트의 치유 효과에 미치는 영향을 고찰하였다. 실험결과에 따르면 자기치유물질만 혼입한 경우와 자기치유물질과 Ca-Al LDH를 함께 혼입한 경우 균열 발생 직후 영동확산계수는 대부분 OPC 배합에 비해 더 컸지만, 치유재령이 경과할수록 OPC 보다 더 큰 폭으로 영동확산계수가 감소하며, Ca-Al LDH를 함께 혼입한 경우가 자가치유 물질만 혼입한 경우보다 영동확산계수 감소가 더 크게 나타나 더 높은 자기치유 성능을 보였다. 이는 균열면에 자기치유 반응생성물이 증가하면서 균열 내부에서 LDH에 의한 염소이온의 구속작용이 더 커진다는 것을 시사한다.