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This thesis sets out to solve a paradox: maintaining a high level of employees' affective commitment to the organisation is assumed to be a critical factor for successful downsizing, but downsizing tends to reduce employees' affective commitment to the organisation. In seeking to resolve this paradox, the thesis aims to provide insights into how employees' affective commitment to the organisation under downsizing can be managed. The thesis first explores the mechanism through which downsizing exerts its influence on employees' affective commitment to the organisation, i.e. it examines whether downsizing affects employees' affective commitment to the organisation directly and/or indirectly through employees' daily work experiences, and seeks to determine which impact is stronger. Then, it examines whether employees' affective commitment to the organisation is really important in terms of organisational citizenship behaviour. Finally, the thesis identifies the determinants of employees' affective commitment to the organisation and investigates how and why these determinants have such effects. The results of the research show that the indirect impact of downsizing on employees' affective commitment to the organisation is much stronger than its direct impact. That is, employees' affective commitment to the organisation is slightly reduced by downsizing, but it can be maintained or enhanced if the change of employees' daily work experiences caused by downsizing is favourable to them. Moreover, employees' affective commitment to the organisation appears to be very important in terms of organisational citizenship behaviour. Finally, employees' daily work experiences affect employees' affective commitment to the organisation through their impacts on the three mediating variables (organisation-based self-esteem, perceived organisational support, and self efficacy). The results also show that organisation-based self-esteem is the key mediating variable.

Natural killer (NK) cells are cytotoxic innate lymphoid cells that protect the host from pathogens. NK cells were classically considered part of the innate immune system, participating as a first-line defense against tumor and virus infected cells. However, recent studies have discovered a subset of NK cells with adaptive immune features. This novel subset of NK cells, characterized by downregulation of signaling molecules FcR and expression of NKG2C receptor on cell surface, demonstrated adaptive immune features such as clonal expansion, long-term persistence, and altered effector functions. While recent research has highlighted the significance of adaptive NK cells, there is still limited understanding about how this adaptive NK cell pool is generated. Epidemiological analyses have indicated an association between the presence of adaptive NK cells in humans and seropositivity for human cytomegalovirus (HCMV). However, it has been demonstrated that not all HCMV seropositive individuals have adaptive NK cells, and the co-infection of humans with other viruses makes it difficult to discern the precise contribution of HCMV infection to the development and expansion of the adaptive NK cell pool. In Chapter 2, I investigated the impact of primary CMV infection on the generation of adaptive NK cell pool using rhesus macaque as an animal model. I found that a subgroup of rhesus macaques with naturally acquired rhesus cytomegalovirus (RhCMV) infection possessed FcR-deficient NK cells that resemble phenotypic and functional characteristics of human adaptive NK cells. These cells were not detected in specific pathogen free (SPF) animals, however, experimental RhCMV infection of the SPF animals led to the induction of FcR-deficient NK cells in a strain-specific manner. Serological analysis of non-SPF animals indicated that subclinical infections by other common viruses can contribute to the expansion of this adaptive NK cell pool. NK cells have been shown to be a potential mediator during viral infections, including HIV. While their exact role during the course of HIV infection requires further investigation, recent research has provided insights regarding the impact of HIV infection on NK cell population. Studies have shown that HIV infection alters the distribution and function of NK cell subpopulations, particularly leading to the expansion of unusual CD56neg NK cells. In Chapter 3, I examined the CD56neg NK cell population in HIV-viremic patients, which was reported to be hypo-functional. I found that the majority of CD56neg NK cells found in HIV patients were deficient in the signaling adaptor FcR and were specialized for antibody-dependent effector functions. These FcR-CD56neg NK cells shared characteristics similar to the adaptive NK cells and were hypo-responsive to tumor or cytokine stimulation but highly responsive to HIV-infected cells in the presence of anti-HIV antibodies. This study suggests that despite the previous understanding of CD56neg NK cells as dysfunctional in HIV patients, they may be cytotoxically active during HIV infection and contribute during disease progression. NK cells mediate their cytotoxicity by releasing lytic granules containing granzymes and perforin. Granzymes, expressed in both NK cells and cytotoxic T cells, are a family of serine proteases, which play a crucial role during the elimination target cells by inducing apoptosis. NK cells release several different types of granzymes during their degranulation, thus the killing of a target cell is likely a result of a combined action of different granzymes. Granzyme B (GrB) is the most abundant and well-characterized granzyme, and they were shown to cleave and activate caspases and other cellular proteins that regulate apoptosis. Although numerous studies have revealed the mechanism of GrB-induced cytotoxicity, it is still uncertain whether NK cell cytotoxicity absolutely requires the presence of GrB. In Chapter 4, we generated NK cells that lack the expression of GrB and perforin using CRISPR Cas9 to knockout their genes. These GrB KO and perforin KO NK cells showed stable expression of activating surface receptors, however, GrB KO NK cells showed reduced expression of GrH and GrM compared to control KO. Importantly, I demonstrated that absence of GrB does not affect cytotoxicity of NK cells, while absence of perforin completely disabled NK cell cytotoxicity. These results imply that the role of GrB could be substituted by other types of granzymes. Furthermore, I propose using CRISPR Cas9 to generate specific knockouts of granzymes in human NK cells as a promising model for delineating the specific roles of each granzyme during the NK cell cytotoxicity.

Central pattern generators (CPGs) in the spinal cord are motor circuits that oversee controlling rhythmic motor activities. CPGs are composed of different types of interneurons (INs) that interact with the motor neurons (MNs) to produce the patterns of MN activity that can coordinate limb and body movements. Elucidating how different populations of INs contribute to the spinal CPG circuitry in different ways is crucial to understanding neural circuit formation and function. In addition, to study how neural circuits, such as CPGs recruit muscle and dictate locomotion, a functional neuromuscular junction (NMJ) model is essential. As CPG and NMJ are both important components in understanding spinal locomotion, a cell-culture based model where it is possible to precisely modulate cellular, molecular, or transcriptional cues in well-defined time and space is highly desirable. In this study, an in vitro NMJ and a V2a IN-MN-myotube (MT) circuit were developed as model platforms to study CPGs using the unique cell lines developed previously in the lab: transgenic mouse embryonic stem cell (mESC) lines that can produce enriched cultures of Hb9⁺ MNs and excitatory Chx10⁺ V2a INs. We established and confirmed a co-culture condition for the formation of NMJ between the unique mESC-derived Hb9⁺ MNs and the C2C12-derived myotubes in vitro and qualitatively and quantitatively assessed the functional connection between the two cell types. Our platform was further advanced to include a model IN population, Chx10⁺ V2a INs to develop a platform that allows for the characterization of IN-MN connections in situ. The in vitro circuit was made by co-culturing V2a INs, MNs, and MTs in separate chambers of the microdevice that are connected with the microchannels. A co-culture protocol for all three cell types was established using different seeding strategies and medium combinations. To evaluate the possible network formation in the dissociated cultures of different cell types, microelectrode arrays (MEAs) were used. Utilizing the techniques developed in this project, a more systematic study of rhythm and pattern generation according to the IN composition can be carried out to further elucidate the role of each IN population in circuit formation and function

In the first part of this dissertation research, failure modes of similar laser and dissimilar ultrasonic welds in lap-shear specimens under quasi-static loading conditions were investigated. High strength low alloy (HSLA) steel sheets were used to make laser welded lap-shear specimens. Magnesium and HSLA steel sheets were used to make ultrasonic welded lap-shear specimens. Quasi-static tests were conducted on dog-bone shaped lap-shear specimens for both welds. In order to understand the failure mode of the welds, finite element analyses were conducted to identify the effects of the material properties and the weld geometry. The results of the finite element analyses for the laser weld based on multi-zone non-homogeneous material models show that the higher effective stress-plastic strain curves of the weld and heat affected zones and the geometry of the weld protrusion result in the necking/shear failure mode in the load carrying sheet. The results of the finite element analyses for the dissimilar ultrasonic weld based on multi-zone indentation models show that the weld indentation triggers different plastic flow patterns in the load carrying sheet. In the second part of this dissertation research, closed-form analytical solutions to calculate the load distributions by the rolling elements on the raceway for zero-interference and interference conditions in roller bearings were investigated. A special case involving cam follower roller bearings was also investigated. The contact solutions by Hertz and Persson provided the analytical background for the proposed solutions. These solutions along with an assumption that the multiple contacts of rolling elements are similar to the contact of a lumped body corresponding to the rolling elements were used to derive the proposed solutions. The proposed closed-form solutions require minimal input parameters and therefore are expected to be widely used in the bearing industry. Finite element analyses were conducted to validate the proposed solutions for selected geometries and loads. Based on the proposed solutions, a complete yet simple procedure to estimate the fatigue lives of roller bearings were introduced for use in the bearing design and selection processes.

"Human beings were born from nature and in death they return back to nature." This quote express how closely we are connected to nature which is defined a word as all the plants, animals and things that exist in the universe that are not made by people. We first came from nature, and in this complicated society, we sometimes feel like returning to the peaceful, magnificent and tranquil side of nature. Through my work, I would like to show his interpretation of how nature is. For example, a person can look at the ocean and feel peaceful, but someone else can look at the same ocean and feel depressed. Therefore, in my pieces I would like to show how I see different parts of nature. Another goal of in all of my work is to evoke the landscape of nature, as in painting, and force viewers to feel how nature breathes. To instill the breath of nature into lifeless object is what I strive to achieve in my work and in my life. The works are divided into two different parts that could be described by words like mountain, ocean. Most of my works, entitled Nature Through Sculpture, are composed of copper sheets and are simplified shapes of early Korean mountains in paintings, through modern Korean mountains in paintings. My works challenge viewers to discover an entirely new perspective of traditional sculptures realistically through contemporary sculptures almost as if they were futuristic. Sculptors and their work reflect and create the culture in their own way in modern art. Therefore, artistic works are a kind of aesthetic reflection of the culture. Art as defined by the Korean dictionary originally means, "to join or fit together" and "culture" comes from cultivation and growth. I believe the purpose of art is not to honor and increase its complexity, but to simplify the world and our place in it. From this perspective, functions have changed from time to time and age to age. Though my works, I intend to express lyrical Korean nature. These pieces raise the question of the image of the nature in today's society. I encourage viewers to answer this question when seeing my emotional works.