• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.4
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• pp.207-215
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• 2014

Password based authentication systems are most widely used for user convenience in web services. However such authentication systems are known to be vulnerable to various attacks such as password guessing attack, dictionary attack and key logging attack. Besides, many of the web systems just provide user authentication in a one-way fashion such that web clients cannot verify the authenticity of the web server to which they set access and give passwords. Therefore, it is too difficult to protect against DNS spoofing, phishing and pharming attacks. To cope with the security threats, web system adopts several enhanced schemes utilizing one time password (OTP) or long and strong passwords including special characters. However there are still practical issues. Users are required to buy OTP devices and strong passwords are less convenient to use. Above all, one-way authentication schemes generate several vulnerabilities. To solve the problems, we propose a multi-channel, multi-factor authentication scheme by utilizing QR-Code. The proposed scheme supports both user and server authentications mutually, thereby protecting against attacks such as phishing and pharming attacks. Also, the proposed scheme makes use of a portable smart device as a OTP generator so that the system is convenient and secure against traditional password attacks.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.369-381
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• 2011

Ginseng in Korea has not only the big production value but also till a good reputation from overseas in the name of 'Korea Ginseng'. Having spread rapidly nationwide from 2000 year, its production keeps on increasing but its consumption becomes lazy and its price is also falling down because of comsumer's concern about mainly overusing pesticide for ginseng. In order to cope with this problem, the government introduced the GAP certification system to ginseng in 2006 to reflect consumer's needs for food safety. This system will be a good opportunity to promote ginseng consumption dramatically. In this aspect it is very important to know how well this system is established and how ginseng farmers build marketing strategies to draw new wind in the market. This study was carried out to look over the GAP certified ginseng system and show its marketing strategies using 4P's(product, place, promotion and price). The main results are as follows. GAP ginseng system currently has some weaknesses such as lack of systematic certification management and after-service, nonrealistic certification fee and poor linkage from production to consumption. In the marketing mix strategies, product strategy suggests that the most desirable appearance be transplanted ginseng filled with branch roots and 4 to 5 year-ginseng, and it is necessary to choose multi-brand strategy divided for present into for self-sufficiency and family brand strategy by use if its brand enlarges to processed products in the future. In the place strategy, 3 stages like 'producer group' - 'GAP certified facility' - 'sales shop' are based as the physical marketing channel according to traceability, and connected with giant retail market and environment friendly stand, and if its sales volume enlarges, it should be considered the GAP ginseng specialized marketplace which is a type of chain store. In the promotion strategy, the promotion of government level is necessary at first and producer alliances require the promotion targeting at the group of women under 40 with differentiation from price, quality, and safety. In the price strategy, the early stage-high price strategy which sets 20~25% higher for self-sufficiency and 30~35% for present is desirable.

• Journal of Digital Convergence
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• v.13 no.11
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• pp.409-415
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• 2015

Summary. With the advent of the internet and the concept of social network service, people of present days are flooded daily with new varieties of the communication channel. One of the most affected group of people may be singing artists. This over-growing number of communication channels pushes singers to put just as many efforts to establish and groom his or her unique identity as an artist. In old 'pre-internet' days, any singing artist's superficial features, like the tone of voice or stage presentation, were the only transcriptive criteria upon which the artist was adjudicated. New developments in technology, however, have set a new paradigm for singing artists of the present day. Respective criteria of today extend beyond the realm of music and comprise musicianship, requiring much scrupulous attention on the various area to propagate and protect one's unique identity as an artist. In light of this phenomenon, this study looks into Mr. Lee, Seung Hwan whom may undoubtedly be one of the most representative ballad singers of 90's. We can probably see his music in 5 features such as Rock Sound based on using various instruments, World Music Sound, Massive Choir, Challenge for the New Style, Lyrics of Life. As a singer-songwriter, he colored numerous albums and influenced the era, unlike many others. He still works vigorously, worthy of his epithet, a 'present-progressive' artist. The object of this study is how Mr. Lee has been proactively dealing with the phenomenon above.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.84-93
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• 2006

Ethernet-PON is an emerging access network technology that provides a low-cost method of deploying optical access lines between OLT and ONUs. It has a point-to-multipoint and multipoint-to-point architecture in downstream and upstream direction, respectively. Therefore, downstream packets are broadcast from an OLT toward all ONUs sithout collision. On the other hand, since alt ONUs share a common channel, the collision may be occurred for the upstream transmission. Therefore, earlier efforts on Ethernet-PON have been concentrated on an upstream MAC protocol to avoid collision. But it is needed to control downstream traffic in practical access network, where the network provider limits available bandwidth according to the number of users. In this paper, we propose a traffic control scheme for supporting the fairness of the downstream bandwidth. The objective of this algorithm is to guarantee the fairness of ONUs while maintaining good performance. In order to do this, we define the service probability that considers the past traffic information for downstream, the number of tokens and the relative size of negotiated bandwidth. We develop the simulation model for Ethernet-PON to evaluate the rate-limiting algorithm by using AWESIM. Some results are evaluated and analyzed in terms of defined fairness factor, delay and dropping rate under various scenario.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.1-11
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• 2015

WBAN(Wireless Body Area Network) operating around the human body aims at medical and non-medical service at the same time. and it is the short-range communication technology requiring low-power, various data rate and high reliability. Various studies is performing for IEEE 802.15.4, because IEEE 802.15.4 can provide high compatibility for operate WBAN among communication standard satisfiable these requirements. Meanwhile, in the case of coexisting many IEEE 802.15.4-based WBAN, signal interference and collision are the main cause that is decreasing data reliability. but IEEE 802.15.4 Standard does not consider about coexistence of many networks. so it needs improvement. In this paper, To solve about this problem, identify coexistence problem of IEEE 802.15.4-based WBAN by preliminary experiments. and propose a scheme to mitigate the reliability decrease at multiple coexistence WBAN. The proposed scheme can be classified in two steps. The first step is avoidance to collision on the CFP through improving data transmission. The second step is mitigation collision through converting channel access method. Proposed scheme is verified the performance by performing comparison experiment with Standard-based WBAN.

• Journal of the Korean Geographical Society
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• v.43 no.6
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• pp.808-823
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• 2008

Sediment abrasion in rivers is caused by the interaction between bedrock channel bed and sediment particles transported through the river. Abrasion rate of sediment particles in rivers is controlled by two major factors; Sediment transport conditions including hydraulic conditions form the erosive forces and physical and chemical strengths of the particles form a resistance force against abrasion and other erosional processes. Physical experiments were performed to find the role of each variable on sediment abrasion process. Total 266 sediment particles were used in this experiment. All sediment particles were divided into 11 independent sediment groups with sediment particle size and sediment loads. Each sediment groups were abraded in tumbling mill for up to 8 hours. Changes in weight were recorded by run and total: 2,128 cases of abrasion rate were recoded. Physical strength of rock particles was measured with point load strength index. It is found that sediment abrasion rate has a negative functional relationship point load strength index ($I_{a(50)}$) ($R^2=0.22$). It was suggested that physical strength of sediment particles set the "maximum possible abrasion rate'. As sediment flux increases, abrasion rates of sediment particles with similar point load strength index were changed. It could be concluded that not only physical characteristics of sediment particles, but also sediment transport conditions control sediment abrasion rates.

• Journal of Distribution Research
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• v.11 no.1
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• pp.99-124
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• 2006

The purposes of the study are two-folds. First, it analyzes how factors other than price(e.g. delivery service, saving point policies, free gifts) impact total price for various products and different types of stores. Second, it analyzes how to increase market efficiencies through price level, price differences, and the frequency of price changes for different shops, various products and different types of transactions. By analyzing the price level within different types of stores, there found that prices at on-line store were lower than off-line shops. It also found price differences between pure on-line, hybrid, and off-line store. Comparing prices by product size, there found that pure on-line shops have a lower price compared to others. The results showed that on-line store had lower price variation compared to off-line shops. When comparing pure on-line store to hybrid store, hybrid store had lower price variation. In terms of the frequency of price changes, hybrid stores had higher price fluctuations. In terms of total price differences for delivery distances, pure on-line store had great price fluctuation, excluding cosmetic goods. In conclusion, if we consider price level and price fluctuations, on-line store had more efficiencies and was superior in terms of price effectiveness. Hybrid shops, on the other hand, had greater advantages for seasonal goods and dominant products. Therefore, market entry strategies should differ based on order quantity, type of store(pure on-line, hybrid, off-line), product characteristics(seasonality, product life), etc.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1295-1309
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• 2007

A wireless access point is used for all communications in the infrastructure mode wireless home networking, including communication between mobile nodes in the same service area. When a mobile station in the infrastructure mode wireless home networking moves into a dead zone, the communication between the mobile station and the access point is disconnected. To solve this problem, the existing wireless home network platforms focus on the ad hoc mode wireless home networking. However, the performance of an ad hoc network is poorly decreased when the number of mobile participating in the ad hoc network increases. In addition, although the ad hoc routing technique is necessary to support seamless communication of mobile nodes, the existing routing protocols, such as AODV and DSR, do not consider that a wireless channel state could affect performance significantly. Therefore, we propose a wireless home networking platform based on the ESCOD (End-to-end Seamless multi-hop COnnection based on Dual network mode) technique incorporating the VLR (Virtual Link Routing) scheme that supports end-to-end seamless connections. Extensive experiments show that the proposed wireless home networking platform incorporating the VLR scheme outperforms wireless home networking platforms based on the AODV and the DSR routing protocols respectively in terms of low packet transmission failure rate, fast packet transmission time, high TCP performance, and a wider coverage area of wireless home networks.

• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.493-502
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• 2007

In this paper, we propose a handoff-aware DiffServ scheduler which intends to guarantee various QoS requirements of multimedia services for mobile nodes in TDD/CDMA based wireless networks. TDD is widely used duplexing mechanism in wireless communications. Unlike FDD, TDD allows a node to symmetrically communicate with a base station by using a single frequency band, resulting in high utilization of wireless resources. DiffServ is regarded as a relatively simple QoS support mechanism and thus it is easy to be extended. This is because DiffServ is not a per-flow based mechanisms and it does not require any signaling protocol. However, previously proposed DiffServ schedulers for wired networks can not be deployed directly into wireless networks since they do not consider properties of wireless networks. As a solution to the problem, DSS(DiffServ Supporting Scheduler) was proposed. DSS uses uplink channel, which is originally used for a node to require a base station to transmit packets, to support QoS efficiently. However, QoS does not consider handoff so that it can not support QoS for moving nodes from one cell to the other cell. Therefor. the proposed handoff support QoS mechanism is necessary for TCC/CDMA networks. The proposed scheme allows a mobile node to achieve seamless service without QoS degradation even for the handoff duration.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.385-390
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• 2016

ELoran Systems can provide Position, Navigation, and Time services with comparable performance to Global Positioning Systems (GPS) as a back up or alternative system. High timing and navigation performance can be achieved by eLoran signals because eLoran receivers use "all-in-view" reception. This incorporates Time of Arrival (TOA) signals from all stations in the service range because each eLoran station is synchronized to Coordinated Universal Time (UTC). Transmission station information and the differential Loran correction data are transmitted via an additional Loran Data Channel (LDC) on the transmitted eLoran signal such that eLoran provides improved Position Navigation and Timing (PNT) over legacy Loran. In this paper, we propose a technique for adapting the delay time compensation values in eLoran timing receivers to provide precise time comparison. For this purpose, we have designed a system that measures time delay from the crossing point of the third cycle extracted from the current transformer at the end point of the transmitter. The receiver delay was measured by connecting an active H-field, an E-field and a passive loop antenna to a commercial eLoran timing receiver. The common-view time transfer technique using the calibrated eLoran timing receiver improved the eLoran transfer time. A eLoran timing receiver calibrated by this method can be utilized in the field for precise time comparison as a GNSS backup.