• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.318-326
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• 2000

This paper analyses with the dynamic performance of HVDC System connected to a weak AC system for varying exciter characteristics of synchronous machines connected at the converter bus. Conventionally capacitors are used to supply reactive power requirement at a strong converter bus. However the installation and synchronous machine is essential in a isolated weak network to re-start after a shutdown of HVDC and to increase strength. The dynamic performance of a synchronous machine depends on the characteristics depends on its exciter characteristics. In this paper, several excites types are used to investigate their effect on the dynamic performance of the HVDC system and modifications to standard exciter topogical are suggested to mitigate observed problems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.26-38
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• 2006

To construct seamless collaborative environments, what all participants intent should be delivered, and visual elements such gesture, facial expression, and ambiance should be shared with all participants. In this paper, we propose high-quality video service to support DV(digital video) and HDV(high-definition DV) based on Access Grid(AG) which is a prevalent collaborative system. The proposed service is designed for employing versatile media tools and codecs with SDP(session description protocol) and SAP(session announcement protocol). We also design network-adaptive video transmission module to mitigate the impact of network fluctuation. This periodically monitors multicast performance and controls frame rate on sender side considering network condition. The experimental results over the test bed show that proposed service enhances quality of AG video service and provides seamless high-quality video transport by mitigating the impact of network fluctuation.

• Advances in Traditional Medicine
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• v.7 no.5
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• pp.549-555
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• 2008

Bupleuri radix (Umbelliferae), the dried root of Bupleurum Chinense DC, has been clinically used to mitigate pain sensation. The descending pain control system consists of three major components, and modulation of pain in the periaqueductal gray is the most extensively studied descending pain control system. However, the relation of Bupleuri radix on the descending pain control system has not been clarified. In the present study, modulation of the aqueous extract of Bupleuri radix on glycine-induced ion current in the acutely dissociated periaqueductal gray neurons was investigated by using nystatin-perforated patch-clamp technique under voltage-clamp condition. In the present results, the glycine-induced ion current was significantly suppressed by 0.1 mg/ml Bupleuri radix, while treatment with $10^{-5}\;M$ naltrexone, opioid receptor antagonist, alleviated Bupleuri radix-induced inhibition on glycine-induced ion current. The present study showed that the aqueous extract of Bupleuri radix may activate descending pain control system through inhibition on glycine-induced ion current in the periaqueductal gray neurons and this effect is mediated by opioid receptors.

• Korean Institute of Interior Design Journal
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• v.22 no.5
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• pp.216-224
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• 2013

There are the relevant provisions that apply to building regulations about the Building codes, Fire Protection laws, and more Multi-using interior finish materials businesses etc. The differences between these regulations are as follows: The Building codes is defined the main use of the building according to facilities to used to set the scale by the use of the floor space, On the other hand, Fire Protection laws are the basic purpose and the act of using the architectural space(or sales) by separating object by fire. And Multiple-using Businesses Facilities consist of two regulations engaged in the kind of law and the size of the floor area. One building can not be based on operating facilities and together in Multiple use businesses Law. As such, the Buildings are applied to the Building codes, Fire Protection laws, such as Multi-using Businesses Facilities interior construction industry due to the structural differences in the position of the designer feeling a lot of difficulties and confusion. The Multi-use businesses Facilities engage in the kind of law, the size of the floor area and seating capacity. These can not be based on operating facilities, and consists of two regulations together in one building. This study is purposed to help improving the finish of the interior architecture that is related to the Building code regulations, Fire Protection laws, Multi-using Facilities interior finishing material relevant with the provisions from the law through analyze the case of developed countries, and the current Multiple use Businesses Facilities research range from the law of multiple-using facilities, interior finishing, interior architecture for supervision reasonably and compensation for the interior design. So, Result is as follows: First, interior decorations can be separated the fixed material and the moveable things. second, It should be included multi-using Business though small size business space at the basement floor. third, It should be established statute law that design and construction responsibility. forth, re-testing fire resist performance after some period. and finally, it need to mitigate regulation where be installed sprinkler.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.525-532
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• 2013

Recently. smartphones have been popularized rapidly and now located deep in our daily life, providing a variety of services from banking, SNS (Social Network Service), and entertainment to smart-work mobile office through apps. Such smartphone apps can be easily downloaded from what is known as app store which, however, bears many security issues as software developers can just as easily upload to it. Military apps will be exposed to a myriad of security threats if distributed through internet-basis commercial app store. In order to mitigate such security concerns, this paper suggests a security guidelines for establishing a military-excusive app store and security verification system which prevent the security hazards that can occur during the process of development and distribution of military-use mobile apps.

• Journal of Information Technology Services
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• v.19 no.2
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• pp.125-138
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• 2020

Currently, subway crowding is estimated by observing a specific point at specific hours once or twice every 1 or 2 years. Given the extensive subway network in Seoul Metropolitan Area covering 588 stations, 11 lines and 80 transfer stations as of 2017, implementing crowding mitigation policy may have its limitations due to data uncertainty. A proposal has recently been made to effectively use smart card data, which generates big data on the overall subway traffic related to an estimated 8 million passengers per day. To mitigate subway crowding, this study proposes two viable options based on data related to smart card used in Seoul Metropolitan Area. One is to create a subway passenger pattern model to accurately estimate subway crowding, while the other is to prove effectiveness of early bird policy to distribute subway demand that is concentrated at certain stations and certain time. A subway passenger pattern model was created to estimate the passenger routes based on subway terminal ID at the entrance and exit and data by hours. To that end, we propose assigning passengers at the routes similar to the shortest routes based on an assumption that passengers choose the fastest routes. In the model, passenger flow is simulated every minute, and subway crowding level by station and line at every hour is analyzed while station usage pattern is identified by depending on passenger paths. For early bird policy, highly crowded stations will be categorized based on congestion level extracted from subway passenger pattern model and viability of a policy which transfers certain traveling demands to early commuting hours in those stations will be reviewed. In particular, review will be conducted on the impact of policy implemented at certain stations on other stations and lines from subway network as a whole. Lastly, we proposed that smart card based subway passenger pattern model established through this study used in decision making process to ensure effective implementation of public transport policy.

• Journal of KIISE
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• v.42 no.11
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• pp.1314-1321
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• 2015

Mobile devices employ buffer cache mechanisms, just as in computer systems such as desktops or servers, to mitigate the performance gap between main memory and secondary storage. However, DRAM has a problem in that it accelerates battery consumption by performing refresh operations periodically to maintain the stored data. In this paper, we propose a novel buffer cache scheme to increase the battery lifecycle in mobile devices based on a hybrid main memory architecture consisting of DRAM and non-volatile PCM. We also suggest a new buffer cache policy that allocates buffers based on process states to optimize the performance and endurance of PCM. In particular, our algorithm allocates each page to the appropriate position corresponding to the state of the application that owns the page, and tries to ensure a rapid response of foreground applications even with a small amount of DRAM memory. The experimental results indicate that the proposed scheme reduces the elapsed time of foreground applications by 58% on average and power consumption by 23% on average without negatively impacting the performance of background applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1521-1531
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• 2015

According to the service attributes, D2D communications establish 1-1, or 1-n channels and require the differentiated device discovery technology. This paper proposes a sector-based device discovery mechanism for 1-n D2D communication scenario in LTE-Advanced networks that a disaster happened. Our proposal is a mechanism that can extend the coverage in a disaster situation which a number of devices(survivors) need to be discovered in a short time. In the single cell environment, a larger discovery coverage can be obtained, and in the multi-cell, it is possible to mitigate the interference with adjacent links due to sector-based coverage control. Through a set of simulations, we have confirmed that our proposal has better performance in the number of devices discovered and the interference than the legacy broadcast device discover mechanism.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1A
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• pp.17-24
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• 2012

In this paper, we described a received signal model in terms of the starting point of FFT window and derive a post-detection SINR for the receiver with MMSE filter and the corresponding filter coefficients in order to mitigate the effects of interferences caused by time and frequency selective fading channels and time difference of arrival (TDoA) in OFDMA-based Mesh Networks. In addition, we proposed an MMSE Bidirectional Successive Detection (BSD) technique which can suppress the effects of interferences among multi-nodes without any redundant FFT operations. It was shown by simulation that the proposed interference suppression technique has not an error floor at higher average SNR than 30dB in terms of 64QAM uncoded BER contrary to the conventional techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1136-1144
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• 2010

In this paper, the effects of HARQ feedback error are evaluated in IEEE 802.16m system when the HARQ and ARQ interactions that utilize the HARQ feedback information is used. Also, the HARQ and ARQ interaction scheme considering HARQ feedback errors are proposed. The HARQ and ARQ interaction scheme improve the system throughput by using the HARQ feedback information instead of the ARQ feedback message, which reduce retransmission time. However, errors in the HARQ feedback information generate severe performance degradation. Especially, the local NAK errors between HARQ feedback error critically degrade the performance, because the local NAK errors lead the loss of ARQ blocks. We propose a channel state-based schemes for HARQ and ARQ interactions to mitigate the throughput degradation due to HARQ feedback errors. Simulation results show that the proposed scheme improves the throughput and the delay performance.