• The Korean Journal of Physiology and Pharmacology
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• 제20권6호
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• pp.629-639
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• 2016

The present study was designed to investigate the characteristics of gintonin, one of components isolated from Korean Ginseng on secretion of catecholamines (CA) from the isolated perfused model of rat adrenal gland and to clarify its mechanism of action. Gintonin (1 to $30{\mu}g/ml$), perfused into an adrenal vein, markedly increased the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. The gintonin-evoked CA secretion was greatly inhibited in the presence of chlorisondamine ($1{\mu}M$, an autonomic ganglionic bloker), pirenzepine ($2{\mu}M$, a muscarinic $M_1$ receptor antagonist), Ki14625 ($10{\mu}M$, an $LPA_{1/3}$ receptor antagonist), amiloride (1 mM, an inhibitor of $Na^+/Ca^{2+}$ exchanger), a nicardipine ($1{\mu}M$, a voltage-dependent $Ca^{2+}$ channel blocker), TMB-8 ($1{\mu}M$, an intracellular $Ca^{2+}$ antagonist), and perfusion of $Ca^{2+}$-free Krebs solution with 5mM EGTA (a $Ca^{2+}$chelater), while was not affected by sodium nitroprusside ($100{\mu}M$, a nitrosovasodialtor). Interestingly, LPA ($0.3{\sim}3{\mu}M$, an LPA receptor agonist) also dose-dependently enhanced the CA secretion from the adrenal medulla, but this facilitatory effect of LPA was greatly inhibited in the presence of Ki 14625 ($10{\mu}M$). Moreover, acetylcholine (AC)-evoked CA secretion was greatly potentiated during the perfusion of gintonin ($3{\mu}g/ml$). Taken together, these results demonstrate the first evidence that gintonin increases the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. This facilitatory effect of gintonin seems to be associated with activation of LPA- and cholinergic-receptors, which are relevant to the cytoplasmic $Ca^{2+}$ increase by stimulation of the $Ca^{2+}$ influx as well as by the inhibition of $Ca^{2+}$ uptake into the cytoplasmic $Ca^{2+}$ stores, without the increased nitric oxide (NO). Based on these results, it is thought that gintonin, one of ginseng components, can elevate the CA secretion from adrenal medulla by regulating the $Ca^{2+}$ mobilization for exocytosis, suggesting facilitation of cardiovascular system. Also, these findings show that gintonin might be at least one of ginseng-induced hypertensive components.

• 한국경영과학회지
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• 제38권1호
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• pp.153-181
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• 2013

Weather is an influential factor to sales of companies. There have been growing attempts with which companies apply weather to developing their strategic marketing plans. By executing weather marketing activities, companies minimize risks (or negative impacts) of weather to their business and increase sales revenues. In spite of managerial importance of weather management, there are scarce empirical studies that comprehensively investigate its impact and present an efficient method that optimally allocates marketing budget. Our research was conducted in two parts. In the first part, we investigated influences of weather on sales based on real-world daily sales data. We specifically focused on the contextual factors that were less focused in the weather related research. In the second part, we propose an optimization model that can be utilized to efficiently allocate weather marketing budget across various regions (or branches) and show how it can be applied to real industry cases. The results of our study are as follow. Study 1 investigated the impact of weather on sales using store sales data of a family restaurant company and an outdoor fashion company. Results represented that the impacts of weather are context-dependent. The impact of weather on store sales varies across their regional and location characteristics when it rains. Based on the results derived from Study 1, Study 2 proposes a method on how optimally companies allocate their weather marketing budgets across each region.

• 유통과학연구
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• 제10권3호
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• pp.7-13
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• 2012

Recently, with the success of Groupon in the USA using the new business model referred to as social commerce, which is a commercial transaction involving group purchases on social network service (SNS), social commerce business receives much attention. Social commerce is capable of effectively promoting additional purchasing by customers through unprecedented price discounts and limiting the number of purchasers and time allotted for purchases, and is able to achieve promotional effects over and above those of simple product promotion due to customers' voluntary word of mouth. Although social commerce is effective for short-term increase in the sales of products, there are numerous dissenting opinions on whether it can promote repurchasing by customers. In particular, social commerce in Korea focuses only on unprecedented discounted prices and does not have the marketing effect that SNS can produce over and above the sales promotion. The objective of this study is to find the factors that influence the repurchase intention on social commerce and to analyze factors that contribute the social commerce product. For this, this study extracts repurchase intention factors and computes a repurchase probability to assess the influence of factors other than price discount on social commerce customers at the time of repurchasing. In addition, the importance of factors toward sales revenue for each of the social commerce products (e.g., restaurant/café, beauty, tour/leisure, show/exhibition, and fashion/clothes) is estimated by using the computed repurchase probabilities. The repurchase probability through the analysis can be used for development of social commerce business in Korea.

• Journal of Communications and Networks
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• 제10권2호
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• pp.137-147
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• 2008

This paper proposes a novel approach to interference avoidance via inter-cell relaying in cellular OFDMA-TDD (orthogonal frequency division multiple access - time division duplex) systems. The proposed scheme, termed asymmetry balancing, is targeted towards next-generation cellular wireless systems which are envisaged to have ad hoc and multi-hop capabilities. Asymmetry balancing resolves the detrimental base station (BS)-to-BS interference problem inherent to TDD networks by synchronizing the TDD switching points (SPs) across cells. In order to maintain the flexibility of TDD in serving the asymmetry demands of individual cells, inter-cell relaying is employed. Mobile stations (MSs) in a cell which has a shortage of uplink (UL) resources and spare downlink (DL) resources use free DL resources to off-load UL traffic to cooperating MSs in a neighboring cell using ad hoc communication. In an analogous fashion DL traffic can be balanced. The purpose of this paper is to introduce the asymmetry balancing concept by considering a seven-cell cluster and a single overloaded cell in the center. A mathematical model is developed to quantify the envisaged gains in using asymmetry balancing and is verified via Monte Carlo simulations. It is demonstrated that asymmetry balancing offers great flexibility in UL-DL resource allocation. In addition, results show that a spectral efficiency improvement of more than 100% can be obtained with respect to a case where the TDD SPs are adapted to the cell-specific demands.

• Journal of Mechanical Science and Technology
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• 제19권9호
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• pp.1695-1705
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• 2005

Reaction wheels and thrusters are commonly used for the satellite attitude control. Since satellites frequently need fast maneuvers, the minimum time maneuvers have been extensively studied. When the speed of attitude maneuver is restricted due to the wheel torque capacity of low level, the combinational use of wheel and thruster is considered. In this paper, minimum time optimal control performances with reaction wheels and thrusters are studied. We first identify the features of the maneuvers of the satellite with reaction wheels only. It is shown that the time-optimal maneuver for the satellite with four reaction wheels in a pyramid configuration occurs on the fashion of single axis rotation. Pseudo control logic for reaction wheels is successfully adopted for smooth and chattering-free time-optimal maneuvers. Secondly, two different thrusting logics for satellite time-optimal attitude maneuver are compared with each other: constant time-sharing thrusting logic and varying time-sharing thrusting logic. The newly suggested varying time-sharing thrusting logic is found to reduce the maneuvering time dramatically. Finally, the hybrid control with reaction wheels and thrusters are considered. The simulation results show that the simultaneous actuation of reaction wheels and thrusters with varying time-sharing logic reduces the maneuvering time enormously. Spacecraft model is Korea Multi-Purpose Satellite (KOMPSAT)-2 which is being developed in Korea as an agile maneuvering satellite.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1892-1903
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• 2016

Mobile social network is becoming more and more popular with respect to the development and popularity of mobile devices and interpersonal sociality. As the amount of social data increases in a great deal and cloud computing techniques become developed, the architecture of mobile social network is evolved into cloud-based that mobile clients send data to the cloud and make data accessible from clients. The data in the cloud should be stored in a secure fashion to protect user privacy and restrict data sharing defined by users. Ciphertext-policy attribute-based encryption (CP-ABE) is currently considered to be a promising security solution for cloud-based mobile social network to encrypt the sensitive data. However, its ciphertext size and decryption time grow linearly with the attribute numbers in the access structure. In order to reduce the computing overhead held by the mobile devices, in this paper we propose a new Outsourcing decryption and Match-then-decrypt CP-ABE algorithm (OM-CP-ABE) which firstly outsources the computation-intensive bilinear pairing operations to a proxy, and secondly performs the decryption test on the attributes set matching access policy in ciphertexts. The experimental performance assessments show the security strength and efficiency of the proposed solution in terms of computation, communication, and storage. Also, our construction is proven to be replayable choosen-ciphertext attacks (RCCA) secure based on the decisional bilinear Diffie-Hellman (DBDH) assumption in the standard model.

• 복식문화연구
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• 제25권3호
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• pp.285-300
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• 2017

This study analyzes the images of models in womenswear advertisements targeting women in their fifties. The goals of this study are: 1) to investigate beauty ideals for middle-aged women by analyzing models' look age, chronological age, wrinkles, gray hair, hair length, body type, and race; and 2) to explore how ageing is dealt with in advertisements by analyzing the range of bodies shown in advertisements, the color mode of photographs, and the clarity of models' figures in relation to models' look ages. A total of 155 printed advertisements from January 2012 to January 2017 from the brands Daks Ladies, Lebeige, Luciano Choi, PAT, and Zishen were selected for analysis. Womenswear brands targeting middle-aged women reinforce cultural ideals of female beauty that emphasize youth and slenderness. They do this by using thin and slender models, who most often appear to be in their twenties and thirties, and have hair longer than their shoulders. Brands with higher price ranges show a preference for Caucasian models, which reveals that a Caucasian identity is associated with sophistication. In addition, the bodies of models who appear to be in their forties and fifties were concealed by framing photographs mostly above the knees. Older models' features were also obscured via the use of black and white photography, strong lighting and contrast, and digital editing that blurred the boundaries between figures and their backgrounds. These decisions for how to represent models could result in negative self-esteem and a denial of the symptoms of ageing among middle-aged women.

• 대한임상검사과학회지
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• 제41권2호
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• pp.83-92
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• 2009

This study was undertaken to examine the effect of oxidants on membrane transport function in renal epithelial cells. Hydrogen peroxide ($H_2O_2$) was used as a model oxidant and the membrane transport function was evaluated by measuring $Na^+$-dependent phosphate ($Na^+$-Pi) uptake in opossum kidney (OK) cells. $H_2O_2$ inhibited $Na^+$-Pi uptake in a dose-dependent manner. The oxidant also caused loss of cell viability in a dose-dependent fashion. However, the extent of inhibition of the uptake was larger than that in cell viability. $H_2O_2$ inhibited $Na^+$-dependent uptake without any effect on $Na^+$-independent uptake. $H_2O_2$-induced inhibition of $Na^+$-Pi uptake was prevented completely by catalase, dimethylthiourea, and deferoxamine, suggesting involvement of hydroxyl radical generated by an iron-dependent mechanism. In contrast, antioxidants Trolox, N,N'-diphenyl-p-phenylenediamine, and butylated hydroxyanisole did not affect the $H_2O_2$ inhibition. Kinetic analysis indicated that $H_2O_2$ decreased Vmax of $Na^+$-Pi uptake with no change in the Km value. Phosphonoformic acid binding assay did not show any difference between control and $H_2O_2$-treated cells. $H_2O_2$ also did not cause degradation of $Na^+$-Pi transporter protein. Reduction in $Na^+$-Pi uptake by $H_2O_2$ was associated with ATP depletion and direct inhibition of $Na^+$-$K^+$-ATPase activity. These results indicate that the effect of $H_2O_2$ on membrane transport function in OK cells is associated with reduction in functional $Na^+$-pump activity. In addition, the inhibitory effect of $H_2O_2$ was not associated with lipid peroxidation.

• 경영과정보연구
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• 제30권1호
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• pp.87-105
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• 2011

급속한 스마트폰 보급으로 인해 모바일 기기를 이용한 모바일 인터넷 사용은 급속도로 증가하고 있는 실정이다. 하지만 사용자들은 해당 서비스나 기기를 제공하는 만큼 잘 사용하지 못하고 어려움을 겪고 있다. 많은 연구들이 정보기술의 사용에 미치는 품질요인을 이용하여 사용자들의 만족도를 향상시킴으로써 궁극적으로 정보기술을 사용하는 사용자의 삶의 질을 향상시키려고 노력을 하고 있다. 본 연구는 모바일 인터넷 사용에 있어 중요한 사용품질 요인들을 이용하여 사용자의 만족도와 삶의 질에 모바일 인터넷이 얼마나 공헌하는지를 파악하고자 한다. 또한, 사용자의 라이프스타일에 따라 그들의 행동이 어떻게 달라지는지를 파악하고자 한다. 본 연구를 진행하기 위하여 본 연구자는 사용품질 요인에 대한 이론, 라이프스타일에 대한 이론, 삶의 질에 대한 이론을 주요 이론으로 제시하였다. 이를 위해, 본 연구자는 모바일 인터넷 사용자를 대상으로 설문을 실시하였고 이를 실증적으로 분석하였다. 라이프스타일에 따른 사용자 행동차이를 규명하기 위하여 본 연구자는 모바일 인터넷 사용자의 라이프스타일을 파악하였고, 이를 기반으로 라이프스타일 성향에 따른 집단 구분을 실시하였다. 설정된 모델을 기반으로 라이프스타일 성향별 행동차이를 규명하였다. 연구결과, '호기심 많은 독립형'과 '지적 유행추구형'이라는 라이프스타일 성향이 도출되었으며 이 두 집단에 대한 행동차이가 서로 다르게 나타남을 파악할 수 있었다. 이는 모바일 인터넷 사용자들의 행동이 서로 라이프스타일에 따라 다르다는 것을 제시하였고 이를 기반으로 모바일 인터넷 서비스 제공자들이 라이프스타일 성향에 따라 다르게 전략을 구사함을 의미한다.

• 인터넷정보학회논문지
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• 제19권1호
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• pp.49-66
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• 2018

본 연구는 VR-AR 체험(Experiential Uses) 행위과정에 나타난 가치단계 요인을 분석(속성, 기능적 혜택, 심리적 혜택, 사용가치), 이용자의 체험 과정에 나타난 욕구와 이용행위 간의 '가치단계도(HVM : Hierarchical Value Map)'에 관한 모형을 구성하는데 목적이 있다. 이를 위해 '수단-목적 사슬 이론(means-end chain theory)'를 적용, 개인적 VR-AR 경험에 나타난 가치사슬을 측정하였다. 본 연구문제를 해결하기 위하여 1차로 AR-VR 콘텐츠 적합도 측정과 2차로 APT래더링을 활용한 구조화 된 설문지를 통하여 135명의 자료를 분석하여 VR-AR 관련 미디어 이용 선택의 '속성'- '기능적 혜택'- '심리적 혜택'- '이용 가치'에 이르는 수단-목적 가치사슬 구조를 파악한 후 가치단계도(HVM)로 VR-AR체험 가치 관계를 실증할 수 있었다. 연구결과, VR 이용자들은 새로운 가상현실 시청각 요소를 통해 현실이탈, 체험의 생생함, 유행선도를 통하여 새로운 성취감, 재미와 즐거움을 통하여 사회생활을 원활히 하고자 하였다. AR이 가지는 생생함과 주변 상호작용을 통하여 자아실현, 타인과 상호작용에 가치를 두고 있으며,'주변인'의 영향이 크게 작용하였고 이들과의 상호작용이 중요한 선택 목적이었다. 이용자들의 VR-AR 선택의 중요 가치는 타인과 상호작용 증진이며 성취감, 행복과 우호적인 가치 속성도 중요하게 고려되었다.