• Korean Journal of Cognitive Science
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• v.24 no.3
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• pp.203-235
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• 2013

The goal of this paper is to test the findings about English-speaking children's acquisition of inflectional morphemes in the literature using a large-scale database. For this, we obtained a 4.7-million-word corpus from the CHILDES (Child Language Data Exchange System) database, and analyzed 1,630 British and American children's uses of English derivational morphemes up to age 7. We analyzed the type and token frequencies, type per token ratio (TTR), and the lexical diversity (D) for such inflectional morphemes as the present progressive -ing, the past tense -(e)d, the comparative and superlative -er/est with reference to children's nationality and age groups. To sum up our findings, the correlations between the D value and children's age varied from morpheme to morpheme; e.g. we found no correlation for -ing, a marginal correlation for -ed, and a strong correlation for -er/-est. Our findings are consistent with Brown's (1973) classical observation that children learn progressive forms earlier than the past tense marker. In addition, overgeneralization errors were frequently found for -ed, but rarely for -ing, showing a U-shaped developmental pattern at ages 2-3. Finally, American children showed higher D scores than British children, which showed that American children used inflectional morphemes for more word types compared with British children. The present study has its significance in testing the earlier findings in the literature by setting up well-defined methodology for analyzing the entire CHILDES database.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1330-1338
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• 2015

In wireless communication network, the amount of packet data for the video streaming in the playout buffer of the receiver is changed with time according to network condition. If the amount of packet data is less than a specific buffer amount, the buffer underflow problem is generated. On the contrary, if the amount of packet data is more than a given buffer amount, the buffer overflow problem is occurred. When the playout of the video streaming is processed, these buffer underflow and overflow problems cause stop and skip phenomenons and then provide the discontinuity of playout. Therefore, to solve the buffer underflow and overflow problems of the video streaming in wireless communication network, This paper analyzes the combined effect of Token Bucket scheme, which controls the bursty traffic, and AMP(Adaptive Media Playout) scheme, which adaptively changes the playout speed of receiver. Through simulation, we found that the combination of Token Bucket and AMP schemes provides the superiority in terms of the occurrence number of buffer underflow and overflow, the stop duration time and the number of removed frames generated by underflow and overflow, and PSNR.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.155-162
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• 2013

Routing protocol in ad hoc mobile networking has been an active research area in recent years. However, the environments of ad hoc network tend to have vulnerable points from attacks, because ad hoc mobile network is a kind of wireless network without centralized authentication or fixed network infrastructure such as base stations. Also, existing routing protocols that are effective in a wired network become inapplicable in ad hoc mobile networks. To address these issues, several secure routing protocols have been proposed: SAODV and SRPTES. Even though our protocols are intensified security of networks than existing protocols, they can not deal fluidly with frequent changing of wireless environment. Moreover, demerits in energy efficiency are detected because they concentrated only safety routing. In this paper, we propose an energy efficient secure routing protocol for various ad hoc mobile environment. First of all, we provide that the nodes distribute security information to reliable nodes for secure routing. The nodes constitute tree-structured with around nodes for token escrow, this action will protect invasion of malicious node through hiding security information. Next, we propose multi-path routing based security level for protection from dropping attack of malicious node, then networks will prevent data from unexpected packet loss. As a result, this algorithm enhances packet delivery ratio in network environment which has some malicious nodes, and a life time of entire network is extended through consuming energy evenly.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.264-264
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• 1992

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.882-890
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• 2001

The data link layer of Foundation Fieldbus is operated on the basis of scheduling and token-passing disciplines. This paper presents a network design method of Foundation Fieldbus using a bandwidth allocation scheme. Fieldbus traffic consists of periodic data and sporadically generated time-critical and time-available data. The bandwidth allocation scheme schedules the transmission of periodic data. Time-critical and time-available data are transmitted via a token-passing service. The validity of this bandwidth allocation scheme is determined using an experimental model of a network system. The results obtained from the experimental model show that the proposed scheme restricts the delay of both periodic and time-critical data to a pre-specified bound. The proposed bandwidth allocation scheme also fully utilizes the bandwidth resource of the network system.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.277-280
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• 2016

본 논문에서는 오픈 뱅킹 플랫폼의 안전한 권한 부여를 위한 OAuth 인증 과정의 권한코드 획득 단계와 액세스토큰 사용 단계에서의 보안 취약점을 분석하여 위협 모델을 정의하고 위협에 대응하는 방법을 제안한다. 제안 하는 방법은 크게 3단계로 구분한다. 1단계로 핀테크 앱을 등록 한 후, 2단계로 사용자가 권한을 핀테크 앱에 제공하기 위하여 사용자와 핀테크 앱의 신원을 안전하게 확인하고, 액세스토큰을 준비하는 단계, 3단계로 액세스토큰 탈취에 의한 재사용 공격에 대한 안전한 액세스토큰의 사용으로 구성되어 있다. 본 논문에서는 기존 연구와의 비교를 통하여 OAuth 인증 플로우의 보안 위협에 대해 기존 권한승인 획득 단계와 액세스토큰 사용 단계를 포괄하는 넓은 위협에 대응을 할 수 있다.

• Communications of the Korean Mathematical Society
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• v.13 no.3
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• pp.603-627
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• 1998

The leaky bucket scheme is a promising method that regulates input traffics for preventive congestion control. In the ATM network, the input traffics are bursty and transmitted at high-speed. In order to get the low loss probability for bursty input traffics, it is known that the leaky bucket scheme with static leaky rate requires larger data buffer and token pool size. This causes the increase of the mean waiting time for an input traffic to pass the policing function, which would be inappropriate for real time traffics such as voice and video. We present the leaky bucket scheme with dynamic leaky rate in which the token generation period changes according to buffer occupancy. In the leaky bucket scheme with dynamic leaky rate, the cell loss probability and the mean waiting time are reduced in comparison with the leaky bucket scheme with static leaky rate. We analyze the performance of the proposed leaky bucket scheme in discrete-time case by assuming arrival process to be Markov-modulated Bernoulli process (MMBP).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.461-466
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• 1993

This paper focuses on development and implementation of a performance management algorithm for IEEE802.4 token bus networks to serve large-sale integrated systems. The delivery of time critical messages within delay constraints is an important criterion in the design and management of computer communication networks. In order to achieve this goal, the theory of fuzzy sets has been employed to imitate human's reasoning. The Fuzzy Network Performance Manager(FNPM) is composed of two parts: FNPM1 & FNPM2. FNPM1 is solily intended to satisfy the data latencyfor the highest priority while the other part is trying to satisfy those for the lower priorities. The FNPM requires average data latency, throughput, and token circulation time for its inputs. The efficacy of the FNPM has been evaluated by a series of simulation experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.292-298
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• 2002

We focus on the slicing off some sub-nets using the transitive matrix. Control flows in the Petri nets is done based on the token flows. One control f]ow explains the independent tokens status and if the token-in divides into several tokens after firing a transition then the control flow divides to several flows, as well. Accordingly, we define that the basic unit of concur-rency (short BUC) is a set of the executed control flows based on the behavioral properties in the net. The BUC is S-invariant which has one control flow. We show the usefulness of transitive matrix to slice off some subnets from the original net based on BUC-through on an example.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.2
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• pp.259-267
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• 1997

The advent of B-ISDN using ATM(asynchronous transfer mode) made possible a variety of new multimedia services, however it also created a problem of congestion control due to bursty nature of various traffic sources. To tackle this problem, UPC/NPC(user parameter control/network parameter control) have been actively studied and DRLB(dynamic rate leaky bucket) algorithm, in which the token generation rate is changed according to states of data source andbuffer occupancy, is a good example of the UPC/NPC. However, the DRLB algorithm has drawbacks of low efficiency and difficult real-time implementation for bursty traffic sources because the determination of token generation rate in the algorithm is based on the present state of network. In this paper, we propose a more plastic and effective congestion control algorithm by combining the DRLB algorithm and neural network based prediction to remedy the drawbacks of the DRLB algorithm, and verify the efficacy of the proposed method by computer simulations.