Equation of State in the Presence of Gravity

Hyeong-Chan Kim,Gungwon Kang 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.10

We investigate how an equation of state for matter is affected when a gravity is present. For this purpose, we consider a box of ideal gas in the presence of Newtonian gravity. In addition to the ordinary thermodynamic quantities, a characteristic variable that represents a weight per unit area relative to the average pressure is required in order to describe a macroscopic state of the gas. Although the density and the pressure are not uniform due to the presence of gravity, the ideal gas law itself is satisfied for the thermodynamic quantities when averaged over the system. Assuming that the system follows an adiabatic process further, we obtain a new relation between the averaged pressure and density, which differs from the conventional equation of state for the ideal gas in the absence of gravity. Applying our results to a small volume in a Newtonian star, however, we find that the conventional one is reliable for most astrophysical situations when the characteristic scale is small. On the other hand, gravity effects become significant near the surface of a Newtonian star.

물질의 상태방정식과 중력

김형찬 한국교통대학교 2019 한국교통대학교 논문집 Vol.54 No.-

We investigate how an equation of state for matter is affected by a self gravity. For this purpose, we consider self-gravitating  -identical particles based on the Newtonian gravity. To describe the state of the system, we use the surface values of physical parameters such as density, temperature, pressure. Assuming that the system follows an adiabatic process further, we obtain a new relation between the averaged pressure and density, which differs from the conventional equation of state for the ideal gas in the absence of gravity or in the presence of a background gravity. The problem of entropy which was present for a system in a background gravity is shown to be cured

중력방정식을 이용한 아시아-태평양 국가의 무역패턴 추정

이홍구 ( Hong Gue Lee ) 한국국제통상학회 2002 국제통상연구 Vol.7 No.2

This paper derives an empirical version of the gravity equation in accordance with the theoretical structure of the monopolistic competition model. An effects model has been adopted to estimate the trade patterns of the Asia-Pacific economies. The regression equation relates the amount of bilateral trade flows (both imports and exports) to the sum of GDPs, the product of relative country sizes, the degree of product differentiation, transport costs deflated (or inflated) by the exchange rate variability, and the relative price. Regression results are in overall compliance with theoretical predictions with the exception of the bilateral distances term, one of the pillars of the gravity equation. The gravity model well explains the volume of trade among the APEC members. Both the size of the combined market and the dispersion of country size terms have expected signs with their statistical significance satisfied. On the other hand, the degree of product differentiation or the pattern of comparative advantage is less significant than the previous two variables in explaining the bilateral trade flows.

교역국의 문화적 특성이 식품무역에 미치는 영향 분석

조규대,임태인,김윤형 한국농업경제학회 2023 농업경제연구 Vol.64 No.1

The previous studies have suggested that the cultural characteristics of a country could affect consumer preference attitude toward innovation and international trade. To examine this effect, Hofstede’s multidimensional index of national culture has been popularly used. This paper focuses on the question of how the Hofstede individual cultural indices affect the international food trade using a gravity equation. The results show that the individual cultural characteristics have different effects on the food trade. An increase in the power distance, uncertainty avoidance, and masculinity index is negatively related to food exports, while an increase in the individualism and indulgence index is positively correlated with food exports. On the other hand, the power distance, and masculinity index have been positively related to the food imports, whereas individualism, uncertainty avoidance, and indulgence index have been negatively related to the food imports. Considering the magnitude of the effects in each index, we find that high uncertainty avoidance, long term orientation, and masculinity index restrain the food trade, while the high power distance index tends to increase food imports. Finally, individualism and indulgence index have a greater effect on food exports than imports.

자기장을 이용한 중력의 시공간 변형에 대한 실험적 연구

심충건 한국기계기술학회 2019 한국기계기술학회지 Vol.21 No.4

The curvature of spacetime represented by Einstein field equation has many physical implications, including gravity. As light is deflected by the curvature of spacetime, a magnetic field will also be influenced by the curved spacetime. A permanent magnet is generally known to maintain its persistent magnetic field on the ground as long as there is no external magnetic interference. However, a series of experiments find that there are noticeable changes in the magnetic fields distribution while the permanent magnet rotates. The magnetic field lines of the permanent magnet are deflected towards Earth’s centre, implying a possibility that we can use magnetic field, a more efficient tool than a satellite, to measure the curvature of spacetime. However, comparing the experimental results of this study with theoretically obtained values of the curvature of spacetime remains a vast area of research for future studies.

2차원 진행규칙파열에서의 쇄파현상에 따른 비선형성 파의 특성에 관한 수치적 연구

박종천(Jong-Chun Park),宮田 秀明(Hideaki Miyata) 한국해양공학회 1996 한국해양공학회지 Vol.10 No.3

The breaking phenomenon of regular periodic waves generated by a numerical wave maker is simulated by finite-difference method which can cope with strong interface motions. The air and water flows are simultaneously solved in the time-marching solution procedure for the Navier-Stokes equation. A density-function technique is devised for the implementation of the interface conditions. The accuracy is examined and applied to the simulation of two-dimensional breaking phenomena of periodic gravity waves.

Does Japanese Manufacturing FDI in ASEAN5 Facilitate Trade?

금의민,이창민 한국동북아경제학회 2024 동북아경제연구 Vol.36 No.1

ASEAN countries have traditionally served as production bases for Japanese manufacturing companies, but their expansion slowed in the early 2000s due to the rise of China. However, since the 2010s, amid tensions between Japan and China, as well as between the US and China, the ASEAN region has gained attention as an alternative destination. The paper analyzes the impact of changes in Japanese FDI in the manufacturing sector on trade between Japan and target countries. The analysis focuses on FDI in all 12 sectors of manufacturing in the five major ASEAN countries from 2007 to 2019 and estimates using gravity equations. Given the importance of distance variables in gravity equations, a random effects model is used for estimation. The results indicate that Japanese FDI in the transportation equipment, electronic equipment, and chemical and pharmaceutical industries had a positive correlation with trade with ASEAN5 countries, but no significant results were found in other sectors. Moreover, in transportation equipment and chemical and pharmaceutical industries, the import effect was greater than the export effect. With the Japanese government providing subsidies to manufacturing companies relocating production hubs to ASEAN from 2020 onwards, an increase in trade volume between these countries and Japan is expected in the future.

한국 해외직접투자가 교역에 미치는 영향

이재민,김동욱,이충기 경희대학교(국제캠퍼스) 국제지역연구원 2017 아태연구 Vol.24 No.1

본 연구에서는 우리나라의 해외직접투자가 무역액 및 수출액에 미치는 영향을 중력방정식을 이용하여 분석하였다. 2000년대 이후 우리나라는 국제가치사슬 구조에 기반한 전략적 투자지역 선정에 함께 자유무역협정이 체결되면서 해외생산기지 구축을 위한 해외직접투자가 이루어지고 수출이 확대되고 있었다. 본 연구에서는 해외직접투자가 과연 무역액 및 수출액에 부정적인 영향을 미치는지 혹은 긍정적인 영향을 미치는지를 분석하고자 한다. 또한 해외직접투자와 자유무역협정이 결합되어 서로 간에 상승작용을 일으키는 최근 추세를 반영하기 위해 다양한 계량경제학적인 방법론을 이용하였다. 특히 자유무역협정을 고려한 해외직접투자의 무역액 및 수출액에 미치는 효과를 분석하고자 하였으며, 변수들의 내생성과 패널자료 특성을 감안한 방법론을 적용하였다. 분석 결과에 의하면 해외직접투자는 무역액 및 수출액을 증대시키는 효과가 있는 것으로 나타나 최근 우리나라 무역액 및 수출액의 증대가 해외직접투자에 기인하는 것으로 분석되었다. The purpose of this study is to investigate the impact of foreign direct investment on trade and exports in Korea using gravity equation. Since the 2000s, Korea has concluded free trade agreements in the strategic investment area selection based on the global value chain structure, and foreign direct investment for building overseas production bases has been made, and exports have been expanding. This study attempts to analyze whether foreign direct investment has a negative or positive effect on the amount of trade and export. Recently, foreign direct investment(FDI) and free trade agreements(FTA) have been combined to create a synergistic effect, and various econometric methodologies were used to reflect recent trends in this study. In particular, we analyze the effect of foreign direct investment on the amount of trade and exports considering FTAs and use methods to consider the endogeneity of variables and panel data characteristics. According the results of the analysis, foreign direct investment has an effect of increasing the amount of trade and exports. As a results, it is found out that the increase of the trade value and the export amount of Korea is caused by foreign direct investment.

Trade Facilitation Provisions in Regional Trade Agreements: Discriminatory or Non-discriminatory?

박인원,박순찬 대외경제정책연구원 2016 East Asian Economic Review Vol.20 No.4

trade-creating effect and complement the discriminatory feature of RTAs but have yet to be empirically proven. Recognizing the limitations of existing studies, we conducted a quantitative analysis on the effects of RTAs with and without trade facilitation provisions on both intra- and extra-bloc trade by using a modified gravity equation. We applied the Poisson Pseudo-Maximum Likelihood (PPML) estimation with time varying exporter and importer fixed effect method to panel data consisting of 45,770 country pairs covering 170 countries for 2000-2010. We found that the trade facilitation provisions in existing RTAs are non-discriminatory by generating more intra- and extra-bloc trade in general. In particular, we found that the trade effects of RTAs in the APEC region are much stronger than the general case covering all RTAs in the world. In addition, as we control the trade effect of a country’s trade facilitation, which is ranked by the World Bank’s logistic performance index, RTAs consisting of trade facilitation provisions are discriminatory for trade in final goods and non-discriminatory for trade in intermediate goods. Overall, we endeavor to “explain,” instead of “hypothesizing,” why most of the recent RTAs contain trade facilitation provisions, especially in light of the deepening regional interdependence through trade in parts and components under global value chains and support the necessity of multilateralizing RTAs by implementing non-discriminatory trade facilitation provisions.

Trade Facilitation Provisions in Regional Trade Agreements: Discriminatory or Non-discriminatory?

( Innwon Park ),( Soonchan Park ) 대외경제정책연구원 2016 East Asian Economic Review Vol.20 No.4

The RTAs with trade facilitation provisions have been expected to generate a larger net trade-creating effect and complement the discriminatory feature of RTAs but have yet to be empirically proven. Recognizing the limitations of existing studies, we conducted a quantitative analysis on the effects of RTAs with and without trade facilitation provisions on both intra- and extra-bloc trade by using a modified gravity equation. We applied the Poisson Pseudo-Maximum Likelihood (PPML) estimation with time varying exporter and importer fixed effect method to panel data consisting of 45,770 country pairs covering 170 countries for 2000-2010. We found that the trade facilitation provisions in existing RTAs are non-discriminatory by generating more intra- and extra-bloc trade in general. In particular, we found that the trade effects of RTAs in the APEC region are much stronger than the general case covering all RTAs in the world. In addition, as we control the trade effect of a country’s trade facilitation, which is ranked by the World Bank’s logistic performance index, RTAs consisting of trade facilitation provisions are discriminatory for trade in final goods and non-discriminatory for trade in intermediate goods. Overall, we endeavor to “explain,” instead of “hypothesizing,” why most of the recent RTAs contain trade facilitation provisions, especially in light of the deepening regional interdependence through trade in parts and components under global value chains and support the necessity of multilateralizing RTAs by implementing non-discriminatory trade facilitation provisions.