• Journal of Korea Trade
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• v.26 no.5
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• pp.23-38
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• 2022

Purpose - This research intends to find out whether R&D cost stickiness shows differentiated aspects depending on exports in Korea. A cost behavior that indicates a lower rate of costs decrease when sales decrease than the rate of costs increase when sales increase is called cost stickiness. This sticky cost behavior is caused by considering the adjusting costs. This study aims to empirically verify that R&D cost stickiness is greater in export firms than in non-export firms. We also investigate the effect of exports on R&D cost stickiness is nonlinear. Design/methodology - We obtain data for the analysis from Kis-Value and TS2000 from 2012 to 2020. This study tests for R&D cost stickiness of exports using the cost stickiness model developed by Anderson et al. (2003) that is used in a lot of prior literature. To explore the nonlinear behavior of R&D cost stickiness we include a quadratic term of exports in our model. Findings - The results of our analysis are as follows. First, we observed that R&D costs of export firms are more sticky than that of non-export firms. Our result indicated that export firms are less likely to reduce R&D costs in decreasing sales periods in preparation for future sales recovery. Second, our empirical evidence shows that export firms view R&D costs much favorably. However, we hypothesize that the effect of export intensity on R&D costs may not necessarily be linear. Our result shows the effect of exports intensity on R&D stickiness is thus nonlinear, forming a reverse U-shaped curve. When export intensity exceeds a certain threshold, the growth rate of R&D costs appears to be viewed negatively. Firms with relatively high export intensity do not support R&D costs, viewing them as taking away firms' resources from other more productive costs. On the contrary, those with export intensity under the threshold view R&D costs as beneficial and therefore promote further R&D costs when revenue decreases. Originality/value - The results of this research can contribute academically to the expansion of empirical research on R&D cost stickiness. R&D cost stickiness varies by industry. As a result of our research, the managers of export firms recognize the importance of R&D to lead innovation. We expected that this research contributes to further studies on R&D costs and cost stickiness. Second, this research has implications from a business perspectives. Our findings of export firms' R&D stickiness suggest that export firms' managers should consider keeping the stickiness of R&D when revenue decreases because it is essential for exporting firms to maintain their R&D stickiness to secure long-term competitiveness. R&D stickiness can be used on a practical basis to emphasize the need for continuous investment in exporting firms' R&D activities.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.17-27
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• 2022

A certain level of stability margin airworthiness criteria should be met to secure robustness against uncertainties between the real plant and the model in a flight control system design. The U.S. Department of Defense (DoD) specification of MIL-F-9490D and airworthiness certification standard of MIL-HDBK-516B uses gain and phase margin criteria of flight control system. However, the same stability margin criteria is applied at all development phases without considering the design maturity of each development phase of the aircraft. Ultimately, a problem arises when the aircraft operation envelope is excessively restricted. This paper proposes the relation of handling qualities and stability margin, and presents re-established stability margin criteria as a development phases and verification methods. The results of the research study are considered to contribute to the verification of the stability margin criteria more flexibly and effectively by applying the method to not only the currently manned developing aircrafts but also the unmanned vehicle to be developed in the future.

• International Area Studies Review
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• v.15 no.1
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• pp.291-314
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• 2011

We examine the motives of foreigner's investments in the Korean bonds by maturity and try to prove that market impacts are different by their investment maturity. Foreign investors initially focused on short-term bonds, but have expanded to mid- to long-term bonds since 2010. The previous studies found that covered interest arbitrage was the main reason for foreign investment. However, there should be some other reasons as their investment in mid- to long-term bonds might have nothing to do with arbitrage. In the empirical analysis, we found that foreign investment in bonds with less than 2 year maturity is driven by arbitrage as previous studies. However, investment in bonds with 2-5 year maturity is sensitive to the FX volatility and the stock market performance compared with the U.S. and investment in bonds with more than 5 year maturity is driven by the CDS premium differential between Korea and PIIGS countries. The more foreigners have invested mid- to long-term bonds, the stronger downward pressure has been on the bond yields. In addition, foreign investors indirectly affected the spreads. Meanwhile, the government should prepare some policy measures since concerns over side effects such as the Korean won appreciation and an abrupt capital outflow are arising.

• Asia Marketing Journal
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• v.16 no.1
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• pp.35-69
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• 2014

The impact of competition on pricing has been studied in the context of counterfactual merger analyses where expected optimal prices in a hypothetical monopoly are compared with observed prices in an oligopolistic market. Such analyses would typically assume static decision making by consumers and firms and thus have been applied mostly to data obtained from consumer packed goods such as cereal and soft drinks. However such static modeling approach is not suitable when decision makers are forward looking. When it comes to the markets for durable products with indirect network effects, consumer purchase decisions and firm pricing decisions are inherently dynamic as they take into account future states when making purchase and pricing decisions. Researchers need to take into account the dynamic aspects of decision making both in the consumer side and in the supplier side for such markets. Firms in a two-sided market typically subsidize one side of the market to exploit the indirect network effect. Such pricing behaviors would be more prevalent in competitive markets where firms would try to win over the battle for standard. While such qualitative expectation on the relationship between pricing behaviors and competitive structures could be easily formed, little empirical studies have measured the extent to which the distinct pricing structure in two-sided markets depends on the competitive structure of the market. This paper develops an empirical model to measure the impact of competition on optimal pricing of durable products under indirect network effects. In order to measure the impact of exogenously determined competition among firms on pricing, we compare the equilibrium prices in the observed oligopoly market to those in a hypothetical monopoly market. In computing the equilibrium prices, we account for the forward looking behaviors of consumers and supplier. We first estimate a demand function that accounts for consumers' forward-looking behaviors and indirect network effects. And then, for the supply side, the pricing equation is obtained as an outcome of the Markov Perfect Nash Equilibrium in pricing. In doing so, we utilize numerical dynamic programming techniques. We apply our model to a data set obtained from the U.S. video game console market. The video game console market is considered a prototypical case of two-sided markets in which the platform typically subsidizes one side of market to expand the installed base anticipating larger revenues in the other side of market resulting from the expanded installed base. The data consist of monthly observations of price, hardware unit sales and the number of compatible software titles for Sony PlayStation and Nintendo 64 from September 1996 to August 2002. Sony PlayStation was released to the market a year before Nintendo 64 was launched. We compute the expected equilibrium price path for Nintendo 64 and Playstation for both oligopoly and for monopoly. Our analysis reveals that the price level differs significantly between two competition structures. The merged monopoly is expected to set prices higher by 14.8% for Sony PlayStation and 21.8% for Nintendo 64 on average than the independent firms in an oligopoly would do. And such removal of competition would result in a reduction in consumer value by 43.1%. Higher prices are expected for the hypothetical monopoly because the merged firm does not need to engage in the battle for industry standard. This result is attributed to the distinct property of a two-sided market that competing firms tend to set low prices particularly at the initial period to attract consumers at the introductory stage and to reinforce their own networks and eventually finally to dominate the market.

• Asia Marketing Journal
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• v.15 no.2
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• pp.75-97
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• 2013

While good return policies are suggested as one of the critical services for e-commerce, ambivalence between the burden of the cost and shoppers' satisfaction may prevent e-tailers from increasing their level of leniency. Based on the S-O-R model, this study has attempted to develop a grounded theory to explain how lenient return policies shape online shoppers' perceptions and responses, with a focus on cultural influences in the relationship. In order to check the cultural effects of the lenient return policy, thirty two female and eleven male undergraduate students in South Korean shoppers, who are accustomed to strict return policies, participated in the semi-structured interview. A series of open-ended questions were designed to explore consumers' reactions toward four different levels of the lenient return policy: from the strict type in South Korea to the lenient type in the U.S. Using qualitative research methods, this research has defined three types of dimensions of lenient return policy: return possible period, complexity of progress, and other restrictions. While previous researchers did not pay much attention, the last dimension, other restrictions, is shown to be the most significant in influencing online shoppers' perceptions, especially in South Korea. Also, the impacts on online shoppers' perceptions from the three types of sub-dimensions of return policy were somewhat different. Whereas a longer return possible period was considered more favorable, a medium level of complexity and restrictions were considered more desirable. In summary, this result showed that shoppers in Eastern cultures, i.e. South Korean online shoppers, seem favorable to a medium level of lenient return policies, while allowing for taking precautions against possible fraudulent behaviors and setting other restrictions. Therefore, most of retailers in South Korea recommended that e-tailers who adopt the most lenient return policies raise the bar to guard ethical shoppers from fraudulent users. Next, lenient return policies can enhance ease of use, usefulness, affect, and trust while relieving perceived risk, which is connected to intention to purchase, satisfaction, and loyalty. Interestingly, lenient return policies are more likely to change the behavioral responses of online shoppers, such as return and purchase, rather than change their attitudes or beliefs such as image, satisfaction, and loyalty. This tendency can be seen more clearly in the direct influences of return policy on responses. The reaction to lenient return policy is mostly the intention to return or to purchase. This suggests that return policy serves the e-tailers as a powerful tool in increasing online shoppers' purchase intention at the moment of purchase. Therefore, e-tailers who plan to expand their market to eastern countries, including South Korea, have to build a shield of restrictions around their lenient return policy, rather than immediately applying their original liberalized return policy. Also, e-tailers in South Korea need to review their strict and undifferentiated return policies to deal with the unsatisfied reactions of online shoppers toward their normal return policies. Although the present study was confined to the return policies currently being practiced by popular e-tailers, it would be worthwhile to develop effective return policies separately for each country, especially South Korea, keeping the culture of the relevant country in mind.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.836-842
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• 2023

Under the Welfare of Disabled Persons Act, the national qualification test allows disabled and non-disabled people to appear for the same test, and the deaf do not fall under the reason for disqualification from obtaining a license for power-driven water leisure crafts; therefore, even the deaf can obtain a license. During a risk of collision at sea, ships and power-driven water leisure crafts notify the other party of dangerous signals such as maneuvering and warning signals through sound signals to prevent accidents that may occur because surrounding ships are not visible. However, a method is required to prevent marine accidents that may occur when the deaf cannot hear danger signals through sounds from nearby ships or power-driven water leisure crafts during leisure activities owing to hearing impairment. A sound reception system is a device installed on a ship where missionary work is completely deposed to display the amplification of external sounds and the direction of sound reception on the screen. Through visual display of sound signals such as dangerous signals that cannot be heard owing to hearing impairment, improvement measures were proposed to prevent marine accidents that can occur owing to the inability of the deaf to check sound signals during leisure activities.

• Journal of Life Science
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• v.25 no.10
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• pp.1156-1163
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• 2015

The present study investigated the immunomodulatory properties of four different medicinal plants in a cyclophosphamide-treated Balb/c mouse model. One of the four plants, Ulmus macrocarpa, showed partial resistance against immune suppression induced by cyclophosphamide. The bark of U. macrocarpa, commonly known as the Chinese elm, has been used as a pharmaceutical material in Korean traditional medicine to treat bacterial inflammation and induce wound healing. In this study, water extract of U. macrocarpa, named DEU-7, was used for its immunomodulating functional activity. DEU-7 increased the weight of the spleen and the number of splenocytes but did not significantly affect the liver, kidney, and thymus in vivo. A splenocyte viability assay confirmed that DEU-7 influenced ex vivo splenocyte survival. DEU-7 also increased the levels of cytokines, such as IL-2 and IL-4, and immunoglobulins, such as IgM, IgG, and IgA. These results indicated that DEU-7 is involved in the activation of T and B lymphocytes. In addition, DEU-7 was able to maintain the production of cytokines, such as TNF-α, IL-12, and IFN-γ, in the condition of cyclophosphamide-induced immune suppression, suggesting that DEU-7 activated innate immune cells, even under immune suppression. We concluded that DEU-7 aids immunological homeostasis, thereby preventing immune suppression, and aids both innate and adaptive immune response by maintaining the levels of various cytokines and immunoglobulins. Consequently, it is worth investigating the potential of DEU-7 as a supplemental source for immune-enhancing agents.

• The Korean Journal of Air & Space Law and Policy
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• v.20 no.1
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• pp.87-107
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• 2005

Land Remote Sensing' is defined as the science (and to some extent, art) of acquiring information about the Earth's surface without actually being in contact with it. Narrowly speaking, this is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information. Remote sensing technology was initially developed with certain purposes in mind ie. military and environmental observation. However, after 1970s, as these high-technologies were taught to private industries, remote sensing began to be more commercialized. Recently, we are witnessing a 0.61-meter high-resolution satellite image on a free market. While privatization of land remote sensing has enabled one to use this information for disaster prevention, map creation, resource exploration and more, it can also create serious threat to a sensed nation's national security, if such high resolution images fall into a hostile group ie. terrorists. The United States, a leading nation for land remote sensing technology, has been preparing and developing legislative control measures against the remote sensing industry, and has successfully created various policies to do so. Through the National Oceanic and Atmospheric Administration's authority under the Land Remote Sensing Policy Act, the US can restrict sensing and recording of resolution of 0.5 meter or better, and prohibit distributing/circulating any images for the first 24 hours. In 1994, Presidential Decision Directive 23 ordered a 'Shutter Control' policy that details heightened level of restriction from sensing to commercializing such sensitive data. The Directive 23 was even more strengthened in 2003 when the Congress passed US Commercial Remote Sensing Policy. These policies allow Secretary of Defense and Secretary of State to set up guidelines in authorizing land remote sensing, and to limit sensing and distributing satellite images in the name of the national security - US government can use the civilian remote sensing systems when needed for the national security purpose. The fact that the world's leading aerospace technology country acknowledged the magnitude of land remote sensing in the context of national security, and it has made and is making much effort to create necessary legislative measures to control the powerful technology gives much suggestions to our divided Korean peninsula. We, too, must continue working on the Korea National Space Development Act and laws to develop the necessary policies to ensure not only the development of space industry, but also to ensure the national security.

• Progress in Medical Physics
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• v.14 no.1
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• pp.54-67
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• 2003

The voltage-dependence of N-type calcium current inactivation is U-shaped with the degree of inactivation roughly mirroring inward current. This voltage-dependence has been reported to result from a purely voltage-dependent mechanism. However, $Ca^{2＋}$-dependent inactivation of N-channels has also been reported. We have investigated the role of $Ca^{2＋}$ in N-channel inactivation by comparing the effects of $Ba^{2＋}$and $Ca^{2＋}$ on whole-cell N-current in rat superior cervical ganglion neurons. For individual cells in-activation was always larger in $Ca^{2＋}$ than in $Ba^{2＋}$ even when internal EGTA (11 mM) was replaced with BAPTA (20 mM). The inactivation vs. voltage relationship was U-shaped in both divalent cations. The enhancement of inactivation by $Ca^{2＋}$ was inversely related with the magnitude of inactivation in $Ba^{2＋}$ as if the mechanisms of inactivation were the same in both $Ba^{2＋}$ and $Ca^{2＋}$. In support of this idea we could separate fast ( ${\gamma}$ ～150 ms) and slow ( ${\gamma}$ ～ 2500 ms) components of inactivation in both $Ba^{2＋}$and $Ca^{2＋}$ using 5 sec voltage steps. Differential effects were observed on each component with $Ca^{2＋}$ enhancing the magnitude of the fast component and the speed of the slow component. The larger amplitude of fast component indicates that the more channels inactivate via this pathway with $Ca^{2＋}$ than with $Ba^{2＋}$, but the stable time constants support the idea the fast inactivation mechanism is identical in $Ba^{2＋}$and $Ca^{2＋}$. The results do not support a $Ca^{2＋}$-dependent mechanism for fast inactivation. However, the $Ca^{2＋}$-induced acceleration of the slowly inactivating component could result from a $Ca^{2＋}$-dependent process.

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.54-62
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• 1990

The recovery of vegetatiion and soil properties in the burned fields after forest fire were studied in Chung Cheong Buk Do area, Korea, from July 23 to 28, 1981. Miscanthus sinensis var. purpurascens, Carex humilis and Lespedeza bicolor were dominant species in the burned field of the second year after forest fire as well as unburned field. Especially, Lespedeza bicolor was gradually grown to the dominant species. Lespedeza bicolor, Carex humilis and Miscanthus sinensis var. purpurascens were the dominant species in the burned field of the fifth year after forest fire. Biological spectra of the burned fields were similar to the umburned fields with $H-e-D_1-R_5$ or $Ph-e-D_1-R_5$ from the second year after forest fire. Accordingly, biological spectra were recovered to the unburned fields from the second year. Degree of successiion was DS=423 in the burned field and DS=524 in the unburned field in 1981. The DS of the burned fields was gradually increased and recovered to be similar to the unburned from the second year. In the species diversities and evenness index, H,e and $\beta$ of the burned field in 1981 were higher and $\lambda$ was lower than the unburned field, but all of the indices were recovered to the unburned field from the second or third years. Accordingly, the vegetation of the first year was the complex community in view floristic composition, but it was recovered to the simple community as unburned field fromthe second or third years. In the soil preperties, pH, total nitrogen, available phosphorus, exchangeable potassium, exchangeable calcium and exchangeable magnesium were increased and organic matter was decreased due to forest fire, and then was recovered to the unburned field from the second or third years. The vegetation and soil properties of the burned field after forest fire were similary recovered to the unburned field from the second or third years. Accordingly, there was a close relationship between the trend of vegetation recovery and the changes of soil characteristics after forest fire.