Essays on Testing Hypotheses When Non-stationarity Exists in Panel Data Models

This dissertation consists of two essays on testing hypotheses in panel data models when non-stationarity exists in the model. This is done under the high-dimensional framework where both n (cross-section dimension) and T (time series dimension) are large. In the first essay, I discuss the limiting distribution of the t-statistic; using different panel data estimators and propose using the t-statistic based on Feasible GLS estimator. In the second essay, I develop the bootstrap F-statistic for cross-sectional independence in a panel data model with factor structure. The first essay considers the problem of hypotheses testing in a simple panel data regression model with random individual effects and serially correlated disturbances. Following Baltagi, Kao and Liu (2008), I allow for the possibility of non-stationarity in the regressor and/or the disturbance term. While Baltagi et al. (2008) focus on the asymptotic properties and distributions of the standard panel data estimators, this essay focuses on test of hypotheses in this setting. One important finding, is that unlike the time series case, one does not necessarily need to rely on the super-efficient type AR estimator by Perron and Yabu (2009) to make inference in panel data. In fact, I show that the simple t-ratio always converges to the standard normal distribution regardless of whether the disturbances and/or the regressor are stationary. One caveat is that this may not be robust to heteroskedasticity of the error terms, but it is robust to heterogenous AR parameters across individuals. The Monte Carlo simulations in support of all the results are also provided in this essay. The second essay discusses testing hypotheses of cross-sectional dependence in a panel data model with an introduction of factor structure. Following Bai (2003, 2004, 2009) and Bai, Kao and Ng (2009), I again allow for the possibility of non-stationarity in the regressor and the factor. I give attention to test of hypotheses using F-tests in this setting. The limiting distribution of F-statistics under the high-dimensional framework has not been derived yet in the literature perhaps because of its theoretical complexity. To circumvent this difficulty, this essay suggests the use of wild bootstrap F-tests based on simulation results under various cases where both regressors and factors can be stationary or non-stationary. The Monte Carlo results show that the bootstrap F-tests perform well in testing cross-sectional independence and are recommended in practice. They have the advantage of being feasible even when we do not observe the factors and do not require for formal theoretical approximations. It is also shown that the bootstrap F-tests are robust to heteroskedasticity but sensitive to serial correlation

A Novel Structure of Rolling Piston Type Rotary Compressor

This paper presents a new design of rolling piston type rotary compressor and the analysis of the performance of the novel compressor is conducted. The concept of the novel compressor is to utilize the interior space of the roller as inner working volume. The vane is connected and fixed to the outer cylinder and the inner cylinder, and the split bush is located between the roller and the vane to help revolution of the roller. Therefore, the novel compressor has two working volumes. One is outer volume trapped within the outer cylinder, the vane, and the roller and the other is inner volume trapped within the inner cylinder, the vane, and the roller. In the same frame size, the cooling capacity of the novel compressor is increased by average 34.77% over that of the traditional rolling piston type rotary compressor. This is because the mass flow rate of the refrigerant into the compressor increases due to the increase of the total working volume. However, the input power is also increased by average 23.4% over that of the traditional rolling piston type rotary compressor. It is because the indicated work increases due to inner compression work. As a result, the energy efficiency ratio (EER) of the novel compressor is increased by 9.42% over that of the traditional rolling piston type compressor

The Korean-Japanese territorial dispute over Dokdo/Takeshima

This thesis explores the Korean-Japanese territorial dispute over the sovereignty of Dokdo/Takeshima. The Japanese government has argued that Dokdo/Takeshima is inherently Japanese territory. But this thesis demonstrates the baselessness of this argument by exploring the two countries' views of Dokdo/Takeshima's status before and after the Russo-Japanese War and focuses in particular on Japan's incorporation of Dokdo/Takeshima in 1905 during the Russo-Japanese War, an important episode in the contemporary dispute over the island's status. Before the Russo-Japanese War, both Korea and Japan recognized Dokdo/Takeshima as Korean territory. In the course of the war, Japan attempted to offset Russian threats to Japan's sea lanes by constructing observation posts along the Korean coastline. In doing so, Japanese officials incited a Japanese fisherman to petition to incorporate Dokdo/Takeshima into Japanese territory. In the end, Japan surreptitiously incorporated Dokdo/Takeshima into its territory and constructed an observation post on the island that was dismantled after the war. Nevertheless, Tokyo continued to recognize Dokdo/Takeshima as part of Korean territory even after its incorporation in 1905 and its formal annexation of Korea in 1910.http://archive.org/details/thekoreanjapanes109453091Republic of Korea Air Force author.Approved for public release; distribution is unlimited

Effects of C and Al on hydrogen embrittlement mechanism in medium Mn-Ni steels

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