• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.482-488
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• 2009

Mobile Ad-hoc Networks provide communication without a centralized infrastructure, which makes them suitable for communication in disaster areas or when quick deployment is needed. On the other hand, they are susceptible to malicious exploitation and have to face different challenges at different layers due to its open Ad-hoc network structure which lacks previous security measures. Denial of service (DoS) attack is one that interferes with the radio transmission channel causing a jamming attack. In this kind of attack, an attacker emits a signal that interrupts the energy of the packets causing many errors in the packet currently being transmitted. In harsh environments where there is constant traffic, a jamming attack causes serious problems; therefore measures to prevent these types of attacks are required. The objective of this paper is to carry out the simulation of the jamming attack on the nodes and determine the DoS attacks in OPNET so as to obtain better results. We have used effective anomaly detection system to detect the malicious behaviour of the jammer node and analyzed the results that deny channel access by jamming in the mobile Ad-hoc networks.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.385-395
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• 1999

Video-On-demand system provides electronic video rental services from remote video servers on a broadband communication networks. When we assume some situation that serve the same video stream by batching, each time single video stream became available at server-end side, we face the problem that what video stream to be scheduled at what time instant. Hence, in order to manage the resource bandwidth which is different at each stream, the policy of channel allocation became important factor. In this work, we proposed three type of scheduling policies with queueing, as are cumulative Waiting Time(CWT), Mean Waiting Time(MWT) and Predictable Popular Factor(PPF). While CWT policy is good for popular video, MWT policy was good for non-popular video. Also, we know that PPT policy has some fairness for average wait time and reneging rate of user requests.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.53-64
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• 2017

Aerospace Launch Vehicles (ALV) are generally designed with high reliability to operate in complete security through fault avoidance practices. However, in spite of such precaution, fault occurring is inevitable. Hence, there is a requirement for on-board fault recovery without significant degradation in the ALV performance. The present study develops an advanced fault recovery strategy to improve the reliability of an Aerospace Launch Vehicle (ALV) navigation system. The proposed strategy contains fault detection features and can reconfigure the system against common faults in the ALV navigation system. For this purpose, fault recovery system is constructed to detect and reconfigure normal navigation faults based on the sliding mode observer (SMO) theory. In the face of pitch channel sensor failure, the original gyro faults are reconstructed using SMO theory and by correcting the faulty measurement, the pitch-rate gyroscope output is constructed to provide fault tolerant navigation solution. The novel aspect of the paper is employing SMO as an online tuning of analytical fault recovery solution against unforeseen variations due to its hardware/software property. In this regard, a nonlinear model of the ALV is simulated using specific navigation failures and the results verified the feasibility of the proposed system. Simulation results and sensitivity analysis show that the proposed techniques can produce more effective estimation results than those of the previous techniques, against sensor failures.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.637-640
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• 2005

In the development of a electronic system for a optical payload comprising mainly EOS(Electro-Optical Sub-system) and PDTS(Payload Data Transmission Sub-system), many aspects should be investigated and discussed for the easy implementation, for th e higher reliability of operation and for the effective ness in cost, size and weight as well as for the secure interface with components of a satellite bus, etc. As important aspects the interfaces between a satellite bus and a payload, and some design features of the CEU(Camera Electronics Unit) inside the payload are described in this paper. Interfaces between a satellite bus and a payload depend considerably on whether t he payload carries the PMU(Payload Management Un it), which functions as main controller of the Payload, or not. With the PMU inside the payload, EOS and PDTS control is performed through the PMU keep ing the least interfaces of control signals and primary power lines, while the EOS and PDTS control is performed directly by the satellite bus components using relatively many control signals when no PMU exists inside the payload. For the CEU design the output channel configurations of panchromatic and multi-spectral bands including the video image data inter face between EOS and PDTS are described conceptually. The timing information control which is also important and necessary to interpret the received image data is described.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.05a
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• pp.101-110
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• 2007

Current strategic trends in service distribution and software development in response to Web as a platform represent a paradoxical concurrent pursuit of 'economy of scale' and 'service'. From the software perspective, the major novel elements of the Web 2.0 era are Web as a platform and the emergence of long-tail service enabling web sites to function as an independent distribution channel. The current study analyzed the platform strategy for establishing a community of interactive developer and customers taking the issue of economy of scale into consideration. Software industry should face the new reality and utilize the open source community for cost minimization and securing customer base. Furthermore, Lego-style software development should be adopted for maintaining cost-competitiveness in customized software development.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.342-351
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• 2000

The paper is concerned about the discovery of new physics of the old oriental philosophy of the yin-Yang '||'&'||' five elements. the physical properties of Five Elements are defined, similarly as in thermodynamics, as five different characteristic state in a cyclic system of nature or a human body. Wood is defined as "warm and soft", Fire as "hot and dispersive", Earth as "agglomerating and sticky", Metal as "tensile and crystallizing", and Water as "cool and slippery" state, respectively. Based on the physics of Five Elements and Qi channel theory, five different constitution classification s are made according to the shape of human face, such as long, inverse triangle, circle, square, and triangle geometry, respectively.Since the constitution implies the relative size or strength of 5 major organs, this theory can be applies successfully to the prediction of the susceptibility to specific diseases as well as the analyses of personal character such as emotion and sensibility. The specific character is analyzed with four different aspects; that is, the first and second are caused by the positive and negative side of the strongest organ, the third character by determined the weakest organ, and finally the fourth by the abnormal psychology due to serious illness.bnormal psychology due to serious illness.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.2
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• pp.139-149
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• 2018

In the contemporary era of smart tourism, travelers face more accommodation options than ever before. The rapid expansions of alternative accommodation sector are partially owing to the growth of electronic commerce and the rise of online intermediary platforms. Online travel agencies serve as a critical distribution channel for tourism sectors, and the significance is further increased for small and micro entrepreneurs whose direct communication channels are scarce. Considering the holistic process of customer experience started with a third-party online intermediary, this study explores basic and extended attributes of small and medium-sized alternative accommodation where the comparative value is created. In order to achieve the objective, a research design was developed to synthesize the qualitative evidence. The synthesis encompasses both theoretical and practical perspectives, from a systematic review and opinions of academic professionals to an in-depth interview with an industry expert and the current practices of online travel agencies. This study suggests that the sources of value creation for alternative accommodation are not always consistent with those of the traditional. Accounting for the temporal and spatial dynamics in customer experience, the findings of this study provide insights on the comparative value of alternative accommodation, to both academic and industry audiences.

• Science of Emotion and Sensibility
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• v.23 no.1
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• pp.57-68
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• 2020

This research investigates how digital design agencies and client companies incorporate design thinking-a human-centered approach to solving difficult problems-into their website development processes. Based on a literature review on the design-thinking-driven web development process, multiple case studies of award-winning website projects were performed by in-depth interviews with key practitioners. Through analyses of these cases, their user-centered approaches for website innovation were identified according to the following four phases: web planning (discovery and defining phases) and web design and development (development and delivery phases). Moreover, distinct approaches of design thinking practices were identified according to two website types: a brand promotion website with a killer brand storytelling approach; and a service channel website with a strategic UI/UX-driven approach. Next, the key success drivers of these website projects were suggested in light of the typical themes of design thinking (i.e., human centeredness, research based, context awareness, and collaboration). Some practical limitations were also found in adopting the design-thinking-driven web development process, such as limited research methods and tools, and insufficient prototyping and experimentation. Along with these limitations, it was also discovered that current digital design agencies still face the following challenges in adopting the design-thinking-driven web development process: building a long-term, playful partnership with clients; leveraging decision-makers' design thinking awareness; and coping with limited resources (design thinking practitioners, budgets, and schedules).

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.11 no.1
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• pp.82-98
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• 1998

In the literatual studies on the causes and treatments of the melasma, the results were as follows. 1. Melasma is the blackish patch on the face, is belong to the cartegory of the 'Myunjin(面塵)', 'Myunganzung(면간증)', 'Jakban(雀斑)' etc. in Oriental medicine 2. Melasma is deeply associated with Yangming channel in Meridian, with the spleen, stomach, heart and kidney in Viscera. 3. The pathogenic factors of Melasma is divided five parts. One is insufficient of Yangming's energy in Neijing(內經). Two is incoordination between vital energy and blood caused by wind-evil and phlegm-retention syndrome. Three is anxiety impairing the spleen. Four is kidney-asthenia and fire-hyperactivity. Five is heat-evil. 4. In the treatments of Melasma, Sthenia-syndrome was used cooling blood and activating blood circulation, or dispelling wind-evil and promoting meridian, or expelling fire-evil and removing toxic material etc. Asthenia-syndrome was used invigorating the liver and kidney, or nourishing yin and keeping fire downwards etc. 5. Melasma is concerned with sun-light, is mostly seen in female. 6. In the prescription of Melasma, it was used Jujesamultang(酒製四物湯加減), Okyong -san(玉容散), Chunghwasungitang(沖和順氣湯), Okyongseosisan(玉容西施散), Yukmiji-hwanghwan(六味地黃丸) etc.

• Journal of Information Processing Systems
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• v.10 no.2
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• pp.283-299
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• 2014

Skin detection is used in many applications, such as face recognition, hand tracking, and human-computer interaction. There are many skin color detection algorithms that are used to extract human skin color regions that are based on the thresholding technique since it is simple and fast for computation. The efficiency of each color space depends on its robustness to the change in lighting and the ability to distinguish skin color pixels in images that have a complex background. For more accurate skin detection, we are proposing a new threshold based on RGB and YUV color spaces. The proposed approach starts by converting the RGB color space to the YUV color model. Then it separates the Y channel, which represents the intensity of the color model from the U and V channels to eliminate the effects of luminance. After that the threshold values are selected based on the testing of the boundary of skin colors with the help of the color histogram. Finally, the threshold was applied to the input image to extract skin parts. The detected skin regions were quantitatively compared to the actual skin parts in the input images to measure the accuracy and to compare the results of our threshold to the results of other's thresholds to prove the efficiency of our approach. The results of the experiment show that the proposed threshold is more robust in terms of dealing with the complex background and light conditions than others.