• Journal of Korea Trade
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• 제26권1호
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• pp.33-56
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• 2022

Purpose - This paper explains how free trade agreements (FTAs) work as a building block to achieve global free trade and be better than other trade regimes. Design/methodology - This paper utilizes a trade liberalization game setup. Three countries choose a trade agreement strategy based on a given trade regime. Trade agreement is made only when all member countries agree. The paper evaluates each trade regime concerning FTAs and customs union (CU) by area size of global free trade equilibrium on the technology or demand gap between countries. Findings - FTAs make global free trade easier. In this game, there are two main reasons for failure to reach global free trade. First, a trade regime with FTAs makes non-member face difficulties in refusing trade agreements in the existence of a technology gap than a trade regime without FTAs. Also, a trade regime with FTAs causes it harder to exclude non-members in the existence of a demand gap than a trade regime with only CUs. Therefore, a trade regime with FTAs can work better in reaching global free trade. Originality/value - The concept of "implicit coordination" was used, which assumes that FTA members keep external tariffs for non-members the same as before an FTA. Without this consideration, FTA members lower their tariffs to non-members, and it makes non-member refuse free trade easier. FTA can prevent it sufficiently only with implicit coordination. This makes the trade regime with FTAs more effective to reach global free trade.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.429-439
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• 2003

Counter-current two-phase flows of air- water in narrow rectangular channels with offset strip fins have been experimentally investigated in a 760 mm long and 100 mm wide test section with 3.0 and 5.0 mm gap widths. The two-phase flow regime, channel-average void fractions and two-phase pressure gradients were studied. Flow regime transition occurred at lower superficial velocities of air than in the channels without fins. In the bubbly and slug flow regimes, elongated bubbles rose along the subchannel formed by fins without lateral movement. The critical void fraction for the bubbly-to-slug transition was about 0.14 for the 3 mm gap channel and 0.2 for the 5 mm gap channel. respectively. Channel-average void fractions in the channels with fins were almost the same as those in the channels without fins. Void fractions increased as the gap width increased, especially at high superficial velocity of air. The presence of fins enhanced the two-phase distribution parameter significantly in the slug flow, where the effect of gap width was almost negligible. Superficial velocity of air dominated the two-phase pressure gradients. Liquid superficial velocity and channel gap width has only a minor effect on the pressure gradients.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.941-950
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• 2001

A study of counter-current two-phase flow in narrow rectangular channels has been performed. Two-phase flow regimes were experimentally investigated in a 760mm long and 100mm wide test section with 2.0 and 5.0mm gap widths. The resulting flow regime maps were compared with the existing transition criteria. The experimental data and the transition criteria of the models showed relatively good agreement. However, the discrepancies between the experimental data and the model predictions of the flow regime transition become pronounced as the gap width increased. As the gap width increased the transition gas superficial velocities increased. The critical void fraction for the bubbly-to-slug transition was observed to be about 0.25. The two-phase distribution parameter for the slug flow was larger for the narrower channel. The uncertainties in the distribution parameter could lead to a disagreement in slug-to-churn transition between the experimental findings and the transition criteria. For the transition from churn to annular flow the effect of liquid superficial velocity was found to be insignificant.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.133.2-133.2
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• 2014

A gap surface plasmon resonator have received considerable attention because it can dramatically enhance the absorption of the electromagnetic field. However, whereas most of studies were just focused on the absorption within a narrow range of wavelength, few studies have been performed for the broadband absorption in the visible range. Therefore, in this study, we discuss methods that can induce broadband light absorption using gap plasmon resonance in visible regime. The gap plasmon resonator will offer great potential for appplications to solar cells and bioimaging.

• 기술혁신학회지
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• 제6권2호
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• pp.191-202
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• 2003

The objective of this study is to examine the existence of technology gap convergence between manufacturing sector and Grand Total over 1970 to 2000 under nonlinearity relationship in Korea. We use the concept of technology convergence as the stationarity test of technology gap over the relevant periods. Our empirical results provide two important implications for the future study: First, our empirical results strongly support the nonlinearity for technology convergence in our country and an empirical tests based on the assumption of linearity will be biased and wrong industry and economic policy implications. Second, we find two regimes i.e. technology convergence and technology divergence between manufacture sector and Grand Total in our country over 1970 to 2000. These study results imply that the relevant industry and economic policies for technology and R&D implementations be with a causation.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.546-553
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• 2022

Narrow rectangular channels are employed in nuclear research reactors that use plate-type nuclear fuels, high heat-flux compact heat exchangers, and high-performance micro-electronics cooling systems. Two-phase flow in narrow rectangular channels is important, and it needs to be better understood because it is considerably different than that in round tubes. In this study, mechanistic models were developed for the flow regime transition criteria for various flow regimes in co-current air-water two-phase flow for vertical downward flow inside a narrow rectangular channel. The newly developed criteria were compared to a flow regime map of downward air-water two-phase flow inside a narrow rectangular channel with a 2.35-mm gap width under ambient temperature and pressure conditions. Overall, the proposed model showed good agreement with the experimental data.

• 한국생산제조학회지
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• 제6권3호
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• pp.58-64
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• 1997

A micromechanics model to describe the elastic behavior of fiber or whisker reinforced metal matrix composites was developed and the stress concentrations between reinforcements were investigated using the modified shear lag model with the comparison of finite element analysis (FEA). The rationale is based on the replacement of the matrix between fiber ends with the fictitious fiber to maintain the compatibility of displacement and traction. It was found that the new model gives a good agreement with FEA results in the small fiber aspect ratio regime as well as that in the large fiber aspect ratio regime. By the calculation of the present model, stress concentration factor in the matrix and the composite elastic modulus were predicted accurately. Some important factors affecting stress concentrations, such as fiber volume fraction, fiber aspect ratio, end gap size, and modulus ratio, were also discussed.

• 과학기술학연구
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• 제15권2호
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• pp.263-301
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• 2015

디지털 참여(digital inclusion)는 모든 시민이 지식정보사회에 참여할 수 있는 기회 또는 역량의 확산을 가리키는 개념으로 세계 각국에서 주요한 IT 정책 목표로 설정되고 있다. 디지털 참여 담론은 단순히 새로운 과학기술의 경제적 중요성을 강조하는 것을 넘어 변화하는 과학기술 지형에서 국가, 개인, 그리고 시장의 이상적인 관계를 새로이 제시하고 있다는 면에서 주목할 만하다. 이 연구는 다양한 담론 분석을 통해, 정보화 시대에 개인이 기술적 전문성과 전문가다운 의식을 가진 주체가 됨으로써 국가 발전에 기여해야 한다는 윤리적 체제(ethical regime)가 한국의 디지털 참여 담론 주위로 형성되고 있다고 주장한다. 또한 국가 주도의 윤리적 체제가 IT 준/전문가들의 기술 시티즌십과 충돌하면서 갈등을 일으키며, 이 때 여성의 IT 산업 내 과소대표와 노동에 대한 대안적 해석이 발생함을 지적한다. 우리는 윤리적 체제와 기술 시티즌십이 충돌하는 지점에서, 젠더화, 계층화된 정체성이 발현되는 현상에 주목하는 것이 중요하며 앞으로 그 한계와 발전 가능성에 대한 더 많은 연구가 수행되어야 함을 제안한다. 나아가 이 연구는 기술 시티즌십이라는 개념을 사회의 다양한 계층의 이종적 정체성이 동적으로 구성되는 과정에 적용함으로써 일반 시민에 주로 적용되던 이 분석틀의 확장을 도모하고자 한다.

• 폴리머
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• 제35권6호
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• pp.574-579
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• 2011

자동차 선도장 강판을 위한 핵심 응용기술로서 3-롤코팅 공정을 연구하였다. 본 연구를 위한 3-롤코팅은 저장조로부터 코팅액을 끌어 올리는 pick-up롤, 적절한 코팅 두께로 계량시키기 위한 계량롤, 강판에 직접 코팅시키기 위한 applicator 롤로 구성되어 있다. 전단담화의 유변물성을 갖는 고분자 도료의 코팅 유동 특성과 코팅 운전 영역을 pickup 롤과 계량롤 사이의 속도비와 간격 등의 공정조건과의 상관관계를 통해 고찰하였다. 안정한 코팅 영역에서, 간격이 크거나 속도비가 작을수록 코팅 두께는 증가하였다. 또한, ribbing과 cascade라는 불안정성은 각각 속도비가 낮고 높을 때 관찰되었다. 특히, 속도비가 낮을때, ribbing의 파장과 심각도가 증가함을 확인하였다.

• Wind and Structures
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• 제29권1호
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• pp.1-13
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• 2019

A numerical investigation on forces and flow around three square cylinders in side-by-side arrangement is conducted at a Reynolds number Re = 150 with the cylinder center-to-center spacing ratio L/W = 1.1 ~ 9.0, where W is the cylinder side width. The flowat this Re is assumed to be two-dimensional, incompressible, and Newtonian. The flow simulation is conducted by using ANSYS-Fluent. The flow around the three side-by-side cylinders entails some novel flow physics, involving the interaction between the gap and free-stream side flows as well as that between the two gap flows. An increase in L/W from 1.1 to 9.0 leads to five distinct flow regimes, viz., base-bleed flow (L/W < 1.4), flip-flopping flow (1.4 < L/W < 2.1), symmetrically biased beat flow (2.1 < L/W < 2.6), non-biased beat flow (2.6 < L/W < 7.25) and weak interaction flow (7.25 < L/W < 9.0). The gap flow behaviors, time-averaged and fluctuating fluid forces, time-averaged pressure, recirculation bubble, formation length, and wake width in each flow regime are discussed in detail.