• Tribology and Lubricants
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• v.38 no.1
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• pp.27-31
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• 2022

Harmonic drives have attracted increasing attention with the development of materials, parts, and related equipment. Harmonic drives exhibit high deceleration, high accuracy, and light weight. The stiffness of flexible splines according to the radial load is studied using a commercial FEM program to design the structure of the flexible spline and finite element to improve the weight and price competitiveness of harmonic drives. In addition, several studies have measured and compared friction coefficients based on 3D printed tread patterns. However, owing to the characteristics of plastic materials, a decrease in stiffness in the radial direction is inevitable. To prevent a decrease in stiffness in the radial direction, we designed and manufactured flex splines with a wrinkle shape. Through structural analysis, the reaction force and stiffness in the radial direction were determined. In addition, the maximum angle of the mound was derived by theoretical calculations, and the performance of the harmonic drive was compared with the results obtained in the mound experiment. Structural analysis shows that the shape of wrinkles decreased the stress and reaction force and increased the safety factor in comparison with that of the circular shape. During performance verification through continuous experiments, the developed harmonic drive showed continuous performance similar to that of an actual tank model. It is expected that the flex spline with a compliant spring and wrinkle shape will prevent a decrease in the radial stiffness.

• Asia-Pacific Journal of Business
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• v.13 no.3
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• pp.19-34
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• 2022

Purpose - The purpose of this study is to examine whether a psychological concept enhances healthcare users' service experience. Specifically, the study proposes and empirically examines a model of perceived control in which the user's sense of control is postulated as exerting positive influences upon his/her motivation, self-efficacy associated with his/her role as a patient, and satisfaction with his/her medical service experience. Methodology - Data were collected by a professional research company, using an online survey method. Participants of the study included adults nineteen years or older who had visited a medical service institute at least once during the previous one-year period. For the test of the research hypotheses, structural equation modeling using AMOS was used. Findings - Findings of this study denote a unique insight into the users' comprehension of medical service experiences and their behaviors. First, the concept of perceived control is identified as a factor that enhances the quality of individuals' medical service experiences. A sense of control directly influences medical users' self-efficacy to comply with doctor's recommendations, their motivation to comply with doctor's recommendations, and their satisfaction with the medical service experience. Second, one's perceived self-efficacy is found to exert positive influences upon both motivation and satisfaction. Third, one's motivation to comply with the doctor's recommendation is found to exert a positive influence upon one's satisfaction. Additionally, perceived control is found to exert an indirect influence upon medical service users' satisfaction through the mediation of both self-efficacy and motivation. Research Implications - The findings of the study support the notion that perception of control among medial service users enhances their service experience as patients. The main thrust of this study suggests that it is necessary for healthcare practitioners to consider implementing service encounter strategies that purposefully enhance the sense of control among their patients. The identification of significant inter-relationships among perceived control, motivation, self-efficacy, and satisfaction among medical service customers should also serve as a meaningful seed for further research pursuits.

• Parasites, Hosts and Diseases
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• v.60 no.5
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• pp.309-315
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• 2022

Inflammatory bowel disease (IBD) is a chronic and recurrent illness of the gastrointestinal tract. Treatment of IBD traditionally involves the use of aminosalicylic acid and steroids, while these drugs has been associated with untoward effects and refractoriness. The absence of effective treatment regimen against IBD has led to the exploration of new targets. Parasites are promising as an alternative therapy for IBD. Recent studies have highlighted the use of parasite-derived substances, such as excretory secretory products, extracellular vesicles (EVs), and exosomes, for the treatment of IBD. In this report, we examined whether EVs secreted by Giardia lamblia could prevent colitis in a mouse model. G. lamblia EVs (GlEVs) were prepared from in vitro cultures of Giardia trophozoites. Clinical signs, microscopic colon tissue inflammation, and cytokine expression levels were detected to assess the effect of GlEV treatment on dextran sulfate sodium (DSS)-induced experimental murine colitis. The administration of GlEVs prior to DSS challenge reduced the expression levels of pro-inflammatory cytokines, including tumor necrosis factor alpha, interleukin 1 beta, and interferon gamma. Our results indicate that GlEV can exert preventive effects and possess therapeutic properties against DSS-induced colitis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.284-291
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• 2022

Objectives: This study aimed to analyze the clinicopathological prognostic factors affecting the survival of patients with oral squamous cell carcinoma (OSCC). Materials and Methods: A retrospective study was conducted on patients with OSCC who received treatment at the Oral Oncology Clinic of the National Cancer Center (NCC) from June 2001 to December 2020. The patients' sex, age, primary site, T stage, node metastasis, TNM staging, perineural invasion (PNI), lymphovascular invasion (LVI), differentiation, surgical resection margin, smoking, and drinking habits were investigated to analyze risk factors. For the univariate analysis, a Kaplan-Meier survival analysis and log-rank test were used. Additionally, for the multivariable analysis, a Cox proportional hazard model analysis was used. For both analyses, statistical significance was considered when P<0.05. Results: During the investigation period, 407 patients were received surgical treatment at the NCC. Their overall survival rate (OS) for five years was 70.7%, and the disease-free survival rate (DFS) was 60.6%. The multivariable analysis revealed that node metastasis, PNI, and differentiation were significantly associated with poor OS. For DFS, PNI and differentiation were associated with poor survival rates. Conclusion: In patients with OSCC, cervical node metastasis, PNI, and differentiation should be considered important prognostic factors for postoperative survival.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.6
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• pp.479-499
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• 2022

The lack of a clonal renin-secreting cell line has greatly hindered the investigation of the regulatory mechanisms of renin secretion at the cellular, biochemical, and molecular levels. In the present study, we investigated whether it was possible to induce phenotypic switching of the renin-expressing clonal cell line As4.1 from constitutive inactive renin secretion to regulated active renin secretion. When grown to postconfluence for at least two days in media containing fetal bovine serum or insulin-like growth factor-1, the formation of cell-cell contacts via N-cadherin triggered downstream cellular signaling cascades and activated smooth muscle-specific genes, culminating in phenotypic switching to a regulated active renin secretion phenotype, including responding to the key stimuli of active renin secretion. With the use of phenotype-switched As4.1 cells, we provide the first evidence that active renin secretion via exocytosis is regulated by phosphorylation/dephosphorylation of the 20 kDa myosin light chain. The molecular mechanism of phenotypic switching in As4.1 cells described here could serve as a working model for full phenotypic modulation of other secretory cell lines with incomplete phenotypes.

• Asia-Pacific Journal of Business
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• v.13 no.3
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• pp.261-279
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• 2022

Purpose - The purpose of this study was to examine the effect of regulatory focus on proactive behavior and to examine the mediating effect of work hope between superior's regulatory focus and subordinate's proactive behavior. In addition, the purpose of this study was to investigate the moderating effect of interpersonal justice between regulatory focus and work hope, and the moderated mediating effect of work hope and interpersonal justice in the relationship between regulatory focus and proactive behavior. Design/methodology/approach - This study used data 255pairs(510people) collected from Public organizations such as gu office and private organizations that perform various tasks such as human resources, finance, accounting, marketing, and R&D. The Confirmatory Factor Analysis (CFA) and the multiple regression analysis were used in order to analyze the data. Findings - The result showed that promotion focus was positively related to proactive behavior. In addition, this study found that the relationship between promotion focus and proactive behavior was mediated by work hope. Regarding the moderating roles of perceived interpersonal justice, the results showed that perceived interpersonal justice significantly interacted with promotion focus in influencing work hope. Finally, the moderated mediation analysis showed that the indirect effect of promotion focus on proactive behavior through work hope was valid only for subordinates with high perceived interpersonal justice. Research implications or Originality - In order to increase proactive behavior, it is necessary to focus on promotion focus and to increase the positive psychology such as hope. In addition, it is necessary to increase perception of interpersonal justice.

• The Korea Journal of Herbology
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• v.37 no.5
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• pp.17-26
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• 2022

Objective : The aim of the present study is to examine hepatic lipid-lowering and anti-inflammatory effects of silymarin combined with Jakyakgamcho-tang on non-alcoholic fatty liver disease in a high fat diet-induced obese mice model. Methods : C57BL/6 mice were divided into four dietary groups: (1) Normal, (2) Control (60% high-fat diet), (3) Control + silymarin 50 mg/kg/day (Silymarin), (4) Control + Silymarin 50 mg/kg/day + Jakyakgamcho-tang 100 mg/kg/day (SPG). After 12 weeks administration, mice were sacrificed and lipids and inflammation-related biomarkers were analyzed liver and plasma. Results : Silymarin and SPG treatments significantly lowered body and liver weights compared to the Control. Serumlipids (triglyceride (TG), total cholesterol) and pro-inflammatory cytokines (tumor necrosis factor alpha, interleukin 1𝛽, and IL-6) concentrations were significantly lowered in the Silymarin and SPG groups than the Control group. Silymarin and SPG treatments suppressed hepatic TG level and hepatic lipid droplets compared to the Control. Theses two treatments significantly increased hepatic kinase B1 and AMP-activated protein kinase protein levels, and significantly decreased hepatic key lipogenic enzymes (acetyl-CoA carboxylase, fatty acid synthase and stearyl coenzyme A desaturase 1) protein levels than the Control. SPG also significantly increased hepatic fatty acid oxidation-related protein (peroxisome proliferator-activated receptor alpha and uncoupling protein 2) levels than the Control. Conclusions: Silymarin and SPG suppressed hepatic lipid accumulation by regulating hepatic protein expression, and lowered blood pro-inflammatory cytokines concentrations though the synergic effect of silymarin and Jakyakgamchotang was not clear.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.291-300
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• 2022

Tunnel boring machines combined with the earth pressure balanced shield method (EPB shield TBMs) have been adopted in urban areas as they allow excavation of tunnels with limited ground deformation through continuous and repetitive excavation and support. Nevertheless, the expansion of TBM construction requires much more minor and exquisitely controlled surface settlement to prevent economic loss. Several parametric studies controlling the tunnel's geometry, ground properties, and TBM operational factors assuming ordinary conditions for EPB shield TBM excavation have been conducted, but the impact of excessive excavation on the induced settlement has not been adequately studied. This study conducted a numerical evaluation of surface settlement induced by the ground loss from face imbalance, excessive excavation, and tail void grouting. The numerical model was constructed using FLAC3D and validated by comparing its result with the field data from literature. Then, parametric studies were conducted by controlling the ground stiffness, face pressure, tail void grouting pressure, and additional volume of muck discharge. As a result, the contribution of these operational factors to the surface settlement appeared differently depending on the ground stiffness. Except for the ground stiffness as the dominant factor, the order of variation of surface settlement was investigated, and the volume of additional muck discharge was found to be the largest, followed by the face pressure and tail void grouting pressure. The results from this study are expected to contribute to the development of settlement prediction models and understanding the surface settlement behavior induced by TBM excavation.

• Geomechanics and Engineering
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• v.29 no.2
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• pp.133-143
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• 2022

The catastrophic earthquake-induced failure of slopes concentrically distributed at near-fault area, which indicated the special features of near-fault ground motions, i.e. horizontal pulse-like motion and large vertical component, should have great effect on these geo-disasters. We performed shaking table tests to investigate the effect of both horizontal pulse-like motion and vertical component on dynamic response of slope. Both unidirectional (i.e., horizontal or vertical motions) and bidirectional (i.e., horizontal and vertical components) motions are applied to soft rock slope model, and acceleration at different locations is reordered. The results show that the horizontal acceleration amplification factor (AAF) increases with height. Moreover, the horizontal AAF under unidirectional horizontal pulse-like excitations is larger than that subject to ordinary motion. The vertical AAF does not show an elevation amplification effect. The seismic response of slope under different bidirectional excitations is also different: (1) The horizontal AAF is roughly constant under horizontal pulse-like excitations with and without vertical waves, but (2) the horizontal AAF under ordinary bidirectional ground motions is larger than that under unidirectional ordinary motion. Above phenomena indicate that vertical component has limited effect on seismic response when the horizontal component is pulse-like ground motion, but it can greatly enhance seismic response of slope under ordinary horizontal motion. Moreover, the vertical AAF is enhanced by horizontal motion in both horizontal pulse-like and ordinary motion. Thence, we should pay enough attention to vertical ground motion, especially its horizontal component is ordinary ground motion.

• Journal of Convergence for Information Technology
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• v.11 no.8
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• pp.151-159
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• 2021

The purpose of this study was to examine the mediating effects of Positive Psychological Capital on the relationship between Small Business Enterpreneur's Learning Goal Orientation and Work Engagement. In order to achieve the purpose of research, the survey results of 300 small business Enterpreneurs who participated in the K-BIZ's Small Business Enterpreneurs Support Program were used for analysis. The collected data were analyzed using frequency analysis, reliability analysis, confirmatory factor analysis, descriptive statistical analysis, correlation analysis and structural equation model. The results of this study were as follows: First, learning goal orientation of small business enterpreneurs had positive effect on positive psychological capital. Second, positive psychological capital of small business enterpreneurs had positive effect on work engagement. Third, positive psychological capital of small business enterpreneurs had full mediating effect on the relationship between learning goal orientation and work engagement. Based upon these results, several suggestions were suggested to promote small business enterpreneurs' learning goal orientation, work engagement, and positive psychological capital.