• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.30 no.2
• /
• pp.70-77
• /
• 2022

This study is a study to analyze the stress difference of pilots according to the category of aircraft. According to previous studies, pilot stress is affected by several factors such as flight time, fatigue regulation, and operating environment, and it is known that stress also affects cardiac variability. In this paper, we analyzed that there is a difference in stress according to the operating environment through airline pilots and pilots of educational institutions, and then tested the difference in stress between airplane pilots and helicopter pilots. This study differs in that it is a study that has almost no empirical research on pilot fatigue and stress considering the role of flight crew members and operational conditions for each mission. If we expand and verify the sample of the results for the stress difference in the future, it will be a great contribution to practical aviation safety research in connection with the fatigue risk management system in the future.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.42
• /
• pp.7.1-7.8
• /
• 2020

Maxillomandibular advancement (MMA) is effective for the treatment of obstructive sleep apnea (OSA). In previous studies, the airway was increased in the anteroposterior and transverse dimensions after MMA. However, the effect of the opposite of mandibular movement (mandibular setback) on the airway is still controversial. Mandibular setback surgery has been suggested to be one of the risk factors in the development of sleep apnea. Previous studies have found that mandibular setback surgery could reduce the total airway volume and posterior airway space significantly in both the one-jaw and two-jaw surgery groups. However, a direct cause-and-effect relationship between the mandibular setback and development of sleep apnea has not been clearly established. Moreover, there are only a few reported cases of postoperative OSA development after mandibular setback surgery. These findings may be attributed to a fundamental difference in demographic variables such as age, sex, and body mass index (BMI) between patients with mandibular prognathism and patients with OSA. Another possibility is that the site of obstruction or pattern of obstruction may be different between the awake and sleep status in patients with OSA and mandibular prognathism. In a case-controlled study, information including the BMI and other presurgical conditions potentially related to OSA should be considered when evaluating the airway. In conclusion, the preoperative evaluation and management of co-morbid conditions would be essential for the prevention of OSA after mandibular setback surgery despite its low incidence.

• Advances in environmental research
• /
• v.11 no.1
• /
• pp.17-30
• /
• 2022

Road transport allows all forms of land conditions to be met at less cost. Because of this function, despite numerous disadvantages, it becomes the most frequently used method of transport, especially in underdeveloped or developing countries. One of the most significant factors used in evaluating the atmosphere's air quality is the amount of CO₂, increasing people's density in indoor spaces. The amount of CO₂ indoors is, therefore, vital to determine. In this study, CO₂ and temperature measurements made on nine different bus journey was made in Turkey. The minimum and maximum values were recorded as 555 ppm and 3000 ppm CO₂, respectively, in the measurements. On all journeys, the average concentration is 1088.72 ppm. The minimum and maximum values were measured as 17.4℃ and 32.7℃ in the temperature measurements, and the average of all trips was calculated to be 25.76℃. In this study conducted before the Covid-19 pandemic, it was determined that the amount of CO₂ increased with the density and insufficient ventilation in the buses. The risk of infection increases in places with high human density and low clean air. For situations such as pandemics, CO₂ measurement is a rapid indicator of determining human density.

• East Asian Journal of Business Economics (EAJBE)
• /
• v.11 no.2
• /
• pp.109-118
• /
• 2023

Purpose - This research paper aims to examine the impact of entrepreneurial orientation (EO) and government support programs (GSP) on new product performance in Korean Small and Medium-sized Enterprises (SME). We specifically focus on the interaction between these two factors and their influence on the new product performance of Korean SMEs. Research design, data, and methodology - We collected survey questionnaires from SMEs that are certified with Inno-biz by the Korean Ministry of SMEs and Startups. The collected data was analyzed using SPSS 26 and AMOS to create an integrated model. Result - Based on the analysis, our findings indicate that the proactiveness and innovativeness dimensions of EO have a positive effect on new product performance. However, the risk-taking dimension of EO has a negative effect. Additionally, GSP exhibit both positive and negative moderating effects on different dimensions of EO. Conclusion - It is important to recognize that GSP are not a universal solution for all challenges faced by SMEs. Hence, it is crucial for policy-makers to have a clear understanding of SMEs' capabilities and the level of EO dimensions in order to identify types of GSP that could lead to positive outcomes, while minimizing the negative effects of GSP.

• Geomechanics and Engineering
• /
• v.33 no.5
• /
• pp.463-475
• /
• 2023

Tunnel construction activity, conducted mainly in mountains and within urban centres, causes soil settlement, thus requiring the relevant management of slopes and structures as well as evaluations of risk and stability. Accordingly, in this study we performed a three-dimensional finite element analysis to examine the behaviour of piles and pile cap stability when a tunnel passes near the bottom of the foundation of a pile group connected by a pile cap. We examined the results via numerical analysis considering different conditions for reinforcement of the ground between the tunnel and the pile foundation. The numerical analysis assessed the angular distortion of the pile cap, pile settlement, axial force, shear stress, relative displacement, and volume loss due to tunnel excavation, and pile cap stability was evaluated based on Son and Cording's evaluation criterion for damage to adjacent structures. The pile located closest to the tunnel under the condition of no ground reinforcement exhibited pile head settlement approximately 70% greater than that of the pile located farthest from the tunnel under the condition of greatest ground reinforcement. Additionally, pile head settlement was greatest when the largest volume loss occurred, being approximately 18% greater than pile head settlement under the condition having the smallest volume loss. This paper closely examines the main factors influencing the behaviour of a pile group connected by a pile cap for three ground reinforcement conditions and presents an evaluation of pile cap stability.

• Asia-Pacific Journal of Business
• /
• v.13 no.4
• /
• pp.79-89
• /
• 2022

Purpose - The purpose of this study was to examine the impact of ESG rating changes of companies listed in Korean Stock Exchange on stock returns. Design/methodology/approach - This study collected prices and ESG ratings of all the companies listed on the Korea Composite Stock Price Index. Based on yearly change of ESG ratings we grouped companies as 2 portfolios(upgrade and downgrade) and calculated portfolios' return. Findings - First, the difference in returns between upgraded and downgraded portfolios is small and statistically insignificant. Second, however, in the COVID-19 period (2020 ~ 2021), the upgraded portfolio outperforms the downgraded portfolio by 0.7 percentage points per month. The difference in returns between upgraded and downgraded portfolios is statistically significant after controlling for the Carhart four factors. Lastly, there are much higher volatility when the ESG rating changes are made of companies with low levels of ESG ratings. Research implications or Originality - This study is the first to examine the impact of ESG rating changes on stock returns in Korea. Furthermore, the findings can serve as a reference for managers who want to control a firm's risk by ESG rating changes. Practically, asset managers can use the findings to construct portfolios that are less risky or more profitable than the market portfolio.

• Journal of Digestive Cancer Research
• /
• v.10 no.1
• /
• pp.31-38
• /
• 2022

Ulcerative colitis (UC) exhibits chronic intestinal inflammatory conditions with cycles of relapse and remission. The incidence is rapidly growing in Asian countries including South Korea possibly due to changes in lifestyles. Although the etiology of inflammatory bowel disease is inconclusive, gut microbiota composition is considered a critical factor involved in the pathogenesis of UC. The overgrowth of pathogenic bacteria evokes hyper-immune responses in gut epithelium causing tissue inflammation and damage. Also, failure to regulate gut epithelium integrity due to chronic inflammation and mucus depletion accelerates bacterial translocation aggravating immune dysregulation. Gut microbiota composition responds to the diet in a very rapid manner. Epidemiological studies have indicated that the risk of UC is associated with low plant foods/high animal foods consumption. Several bacterial strains consistently found depleted in UC patients use plant food-originated dietary fiber producing short chain fatty acids to maintain epithelial integrity. These bacteria also use mucus layer mucin to keep gut microbiota diversity. These studies partly explain the association between dietary modification of gut microbiota in UC development. Further human intervention trials are required to allow the use of specific bacterial strains in the management of UC.

• Asia Marketing Journal
• /
• v.14 no.1
• /
• pp.159-174
• /
• 2012

This study investigate the role of consumer's perception of quality in new technology adoption process in China which is given little attention in the field of Information System and Communication Technology. Here, we developed a simple model in the level of consumer perception by exploring the antecedent of perceived quality. Three factors are introduced as determinants of perceived quality: perceived usefulness, perceived risk and trialability. An empirical study is conducted with analysis of the adoption mechanism of a new innovative product. Data analysis results support some of our proposed hypotheses. It indicates that perceived quality is positively related to the adoption intention and fully mediates the relationship between triablility and purchase intention. And we conclude that a product's perceived quality plays an important role in adoption intention. And what makes Chinese customers perceive product's quality good is a trialability of a product. This suggests that when market managers plan to launch products in China, they need to craft an effective strategy based on the market system of the consumer especially understanding the consumers' critical factor for adopting a new product. Chinese are more interested to purchase a product with free trial and free experiential period, therefore, suggesting an advertisement highlighting the trialability of a product is possible in China.

• Korea Trade Review
• /
• v.45 no.3
• /
• pp.71-89
• /
• 2020

This study was carried out to identify the impact of EU GDPR on international trade amid the ongoing digital trade liberalization. To do this, we first looked at the current trend of digital trade liberalization, the role of data in it, and the trade-restrictive elements of EU GDPR. This allowed us to identify the negative impact of GDPR on free trade. It then conducted an interview survey on Korean companies operating in the EU to verify the conclusions reached. The result of this survey showed that the level of GDPR risk perceived by Korean firms was very low compared with those of American, Japanese and Chinese firms. In particular, the impact of GDPR is not clear for Korea's SMEs. It can be assumed that the reason for this is that Korean SMEs are not using data as a major business tool while the capability of SMEs is sufficient to cope with GDPR. In this regard, the government's appropriate policies and further research for SMEs are needed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.50 no.3
• /
• pp.134-139
• /
• 2024

We systematically reviewed the literature on the co-occurrence of squamous cell carcinoma (SCC) and Warthin's tumor (WT), thought to be quite rare, to help reduce misdiagnosis and improve treatment planning. For this systematic review, we searched for articles in the Web of Science and PubMed databases, analyzed relevant studies for forward and backward citations, and identified only articles reporting on the "co-occurrence" of WT and SCC. Of the 237 studies identified, 12 comprising 18 patients met the inclusion criteria, to which we added one study from our institution. Most WTs were associated with SCC in the parotid gland or cervical lymph nodes. Most patients (89.5%) underwent selective or radical neck dissection due to identification of lesions separate from the primary SCC. Despite its frequent co-occurrence with other neoplasms, WT in the parotid or cervical lymph nodes tends to be misdiagnosed as a metastatic node when SCC is observed as the primary tumor. Factors to consider in diagnosis and neck management include identification of an association other than growth or development by lymphangiogenesis and whether the patient is a smoker, a strong risk factor.