• ETRI Journal
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• v.27 no.3
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• pp.319-325
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• 2005

In this paper the effect of temperature on the electrical properties of organic semiconductor disperse orange dye 25 (OD) have been examined. Thin films of OD have been deposited on $In_{2}O_{3}$ substrates using a centrifugal machine. DC current-voltage (I-V) characteristics of the fabricated devices $(Al/OD/In_{2}O_{3)$ have been evaluated at varying temperatures ranging from 40 to $60^{\circ}C$. A rectification behavior in these devices has been observed such that the rectifying ratio increases as a function of temperature. I-V characteristics observed in $Al/OD/In_{2}O_{3)$ devices have been classified as low temperature $({\leq} 50^{\circ}C)$ and high temperature characteristics (approximately $60^{\circ}C$). Low temperature characteristics have been explained on the basis of the charge transport mechanism associated with free carriers available in OD, whereas high temperature characteristics have been explained on the basis of the trapped space-charge-limited current. Different electrical parameters such as traps factor, free carrier density, trapped carrier density, trap density of states, and effective mobility have been determined from the observed temperature dependent I-V characteristics. It has been shown that the traps factor, effective mobility, and free carrier density increase with increasing values of temperature, whilst no significant change has been observed in the trap density of states.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.5
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• pp.290-297
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• 2003

Analytical Expressions of temperature dependent breakdown voltage and on-resistance for silicon power MOSFETs are induced by employing the temperature dependent effective ionization coefficient extracted from temperature dependent ionization coefficients for electron and hole, and electron mobility in silicon. The analytical results for temperature dependent breakdown voltage are compared with experimental results for tile doping concentration, 4x10$^{14}$ cm$^{-3}$ , 1x10$^{15}$ cm$^{-3}$ , 6x10$^{16}$ cm$^{-3}$ respectively. The variations of temperature dependent on-resistance and breakdown voltage dependent ideal specific on-resistance are also compared with the ones reported previously. Good fits with the experimental results ate found for the breakdown voltages within 10% in error for the temperature in the range of 77~300K at each doping concentration.

• Transactions on Electrical and Electronic Materials
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• v.8 no.4
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• pp.174-177
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• 2007

We fabricated organic field-effect transistors (OFETs) based a fluorinated copper phthalocyanine ($F_{16}CuPC$) and copper phthalocyanine (CuPc) as an active layer. And we observed the surface morphology of the $F_{16}CuPC$ thin film. The $F_{16}CuPC$ thin film thickness was 40 nm, and the channel length was $50{\mu}m$, channel width was 3 mm. And we also fabricated the $F_{16}CuPc/CuPc$ double layer FET and with different $F_{16}CuPc$ film thickness devices. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in $F_{16}CuPc$ FET and we calculated the effective mobility. From the double layer FET devices, we observed the higher drain current more than single layer FET devices.

• Korean Institute of Interior Design Journal
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• no.28
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• pp.100-108
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• 2001

The purpose of this study is to develop recommendation of sign system and color codes in making the public interior environment more accessible for the visually impaired persons. The appropriate guidelines in designing the sign system and the color codes in the public interior environment can increase the accessibility, the mobility and the safety for the visually impaired persons including the increasing elderly. By selecting the effective sign system much more desirable results can be brought: Improvement of accessibility, mobility, increase of safety, work efficiency and the psychological stability. Sign system and the color is more important for the weak-sighted people than the normal-sighted in way finding and the orientation strategies. 53 visually impaired persons participated for this study, the answers of the questionaires by the weak-sighted persons are focused on in this research. The data, the needs of users is analysed on the basis of users-oriented. The result of this study can be considered as a basic direction of sign system design and color codes in our codes in our public environment for all people especially visually impaired persons.

• Physical Therapy Korea
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• v.13 no.3
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• pp.18-23
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• 2006

The limited walking ability after a stroke restricts a patient's independent mobility at home and in the community. It also brings about significant social handicaps. Therefore, it is necessary to improve walking ability in community-dwelling persons with stroke. The purpose of this study was to evaluate the effectiveness of gait training and muscle strengthening exercise of lower extremities in persons with chronic stroke. Nineteen community-dwelling individuals with stroke participated in this program. The exercise program lasted for seven weeks, with a 1-hour program twice per week, and it consisted of balance training, gait training, and strengthening of lower extremities. The outcome of the program was assessed by the gait speed, Wisconsin Gait Scale (WGS), Berg Balance Scale (BBS), and Stroke Impact Scale (SIS). Significant effects were found for the WGS, BBS, and mobility and hand function domain of the SIS (p<.05). It was found that short-term gait training exercise could improve quality of gait, balance, and mobility. Therefore, a more effective exercise program is required for community-based persons with stroke.

• Journal of Periodontal and Implant Science
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• v.41 no.1
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• pp.44-50
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• 2011

Purpose: Pathologic tooth migration (PTM) is a tooth displacement which is derived from imbalance of tooth retention force and is dominantly found out in maxillary anterior area. PTM in maxillary anterior area was tried to corrected with periodontal treatment and a clear aligner in this study and the result was evaluated clinically and radiographically. Methods: For the treatment of a patient with chronic periodontal disease accompanied by maxillary anterior pathologic tooth migration, clear aligner was applied to move teeth after a series of case-related periodontal therapy. Clinically, probing depth, gingival recession, clinical attachment level and mobility were measured pre- and post-treatment, and radiographic examination was performed as well. Results: Clinically, we found the decrease of the probing depth, gingival recession, clinical attachment level and mobility. And we could also acknowledge the reduction of vertical and horizontal dimension on infrabony defect radiographically. However, it is still controversial if there was an actual bone filling. Conclusions: Clear aligner is an effective appliance to move teeth since it costs little in terms of expense and time. In addition, it wraps whole crowns, providing advantages to deal with crowding, spacing, and size of arch. In short, clear aligner could be a useful treatment option for PTM patient, since it provides decreased probing depth, gingival recession, clinical attachment level, mobility and esthetical restoration.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.773-778
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• 2014

IDS(Intrusion Detection System) can be used as a countermeasure for blackhole attacks which cause degrade of transmission performance by causing of malicious intrusion to routing function of networks. In this paper, effects of IDS for transmission performance based on mobility patterns is analyzed for MANET(Mobile Ad-hoc Networks), a suggestion for effective countermeasure is considered. Computer simulation based on NS-2 is used in performance analysis, VoIP(Voice over Internet Protocol) as an application service is chosen for performance measure. MOS(Mean Opinion Score), call connection ratio and end-to-end delay is used as performance parameter.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.323-326
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• 2007

Mobility Anchor Points are used for the mobility management in HMIPv6 networks. Currently a mobile node selects the MAP farthest away from itself as a new MAP among available candidates when it undertakes a macro handoff. With this technique, however, the traffic tends to be concentrated at a MAP with the largest domain size and the communication cost increases due to the distance between the mobile node and the MAP. In this work, we proposed a cost effective MAP selection scheme. When leaving the current MAP domain. the mobile node calculates the optimum MAP domain size to minimize the local mobility cost at the new MAP domain considering mobile node's velocity and packet transmission rate. The mobile node then selects a MAP domain of size close to the optimum domain size calculated among the candidate MAP domains. In this way, it is possible for the mobile node to select an optimal MAP adaptively taking the network and node states into account, thus reducing the communication cost.

• Korea Multimedia Society
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• v.12 no.4
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• pp.28-40
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• 2008

Vehicular ad hoc networks (VANETs) are a practical application class of wireless ad hoc networks, which consist of moving vehicles equipped with radio communication capabilities that collaborate to form a temporary network. This paper addresses issues and protocols of multihop routing in such emerging networks in the context of safety and infotainment applications. Due to the highly dynamic mobility of vehicles, frequent link breakage and short connection time are inevitable and, thus, the routing is a challenging task and interest for many researchers and industrial community. The frequent and dynamic change of topology makes the topology-based routing unreliable but the position-based routing more effective. The position-based routing consists of the location service which maps a node id to a geo-graphical position and the forwarding scheme which selects the next hop based on geo-graphical information of the node, its neighbors and the destination. The routing techniques are further categorized into geographical forwarding, trajectory forwarding and opportunistic forwarding based on the forwarding scheme. In this paper, we first present the distinguished properties of VANETs and the challenges and intractable issues posed in designing the routing protocols, followed by the comprehensive survey of existing routing protocols. Then, the different routing protocols designed for VANETs are compared in terms of characteristics, performance and application domains.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.167-172
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• 2004

Although Mobile IP proposed in IETF is effective. it has inefficiency in case mobile hosts communicate with each others while they are roaming frequently in a specific area. It occurs lots of latency because mobile hosts must be registered and establish an secure path under the internet emvironments and transmitting data on the path. Additionally this inefficiency is more aggravated in case mobile hosts has high mobility. Thus this paper propose a method using Anchor foreign agent by Anchor chain method which combine an pointer forwarding and a cache method plus a border router as a way to complement the above problem which exists in an mobility management in a specific area.