• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.5B
• /
• pp.573-581
• /
• 2011

The underwater channel is known to offer poor communications channel. The channel medium is highly absorptive and the transmission bandwidth is limited. In addition, the channel is highly frequency selective; the degree of selectiveness depends on a detailed geometry of the channel. Furthermore, the response changes over time as the channel conditions affecting the response such as water temperature, sea surface wind and salinity are time-varying. The transceiver design to deal with the frequency and time selective channel, therefore, becomes very challenging. It has been known that deep fading at certain specific sub-carriers are detrimental to OFDM systems. To mitigate this negative effect, the proposed coded OFDM system employs an LDPC code based modulation. In this paper, we aim 1) to provide a detailed underwater channel model; 2) to design a robust LDPC coded OFDM system; 3) to test the proposed system under a variety of channel conditions enabled by the channel model.

• Journal of Korea Multimedia Society
• /
• v.13 no.4
• /
• pp.609-617
• /
• 2010

Since Korean mobile communication companies each use different mobile platforms, developers must configure and translate their game contents to run under each of the platforms so that they can be serviced correctly. Nevertheless, such translation tasks require lengthy times and costs. This is one of the reasons why a variety of contents could not be provided. In order to mitigate such difficulty, this paper implemented an automatic mobile contents translating system that automatically translates mobile C game contents of the GNEX platform to mobile java contents of the WIPI platform. The GNEX C-to-WIPI Java automatic contents translation system helps minimize the amount of time and cost required in servicing contents to different mobile communication companies by promptly translating a platform-specific-content to run under other platforms. Also, the automatic translation and servicing of existing contents increases the reusability of these contents and also the productivity of new contents thereby offering users with a more variety of games.

• 한국HCI학회:학술대회논문집
• /
• 2009.02a
• /
• pp.1172-1175
• /
• 2009

This study aims to develop communication devices and interfaces to address the communication needs of the hearing impaired. Through three FGI (Focused Group Interview)s with deaf persons and sign-language interpreters, we studied the communication methods, devices, and needs of the deaf. On the basis of our analysis, we propose a communication framework to improve their means of communication with normal or other deaf persons. We have designed a communication system that is based on the proposed framework: this system suggests functions for remote sign-language interpretation services for conversations in close-range and over the phone. Details are presented regarding the design of interfaces for video calls, text messages, and digital memos, addressing the conversation patterns of the deaf. The system includes hardware form factors for video phones that facilitate sign language conversations and also mitigate other auditory problems in daily life, such as problems with door bells. The design concept has been verified through a test with six deaf users.

• The KIPS Transactions:PartC
• /
• v.13C no.5 s.108
• /
• pp.575-582
• /
• 2006

Guaranteeing network bandwidth and system performance becomes important technical matters to make seamless delivery of bulky data at high speed. Tuning system and network parameters including jumbo frame, kernel buffer size, and interrupt coalescence determines end-to-end transmission throughput. Additionally, fine-tuning of the parameters alleviates workload on high-end systems. Until now, many studies have concentrated on how to increase transmission throughput but rarely discussed how to mitigate system workload. In this paper, we have investigated various tuning parameters, which positively affect networking and processing performance of uncompressed HDTV system.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.2 s.75
• /
• pp.42-49
• /
• 2007

It has been known that shallow-water regions, such as tidal flats, sea grass and sea weed beds have water purification capability, and they also serve as nursery grounds for many fishes. On the other hand, tidal flat areas are economically attractive sites for reclamation, to be used for developing industries. When developing shallow-water areas, we have to propose a plan to mitigate the environmental impact associated with such a development plan. However, it is difficult to estimate the affects on the ecosystem and water purification, and the literature related to this matter is insufficient. In order to evaluate the ability of coastal tidal flat and to predict the future changes, it is necessary to develop a reliable prediction technique and construction of data by using a field investigation. In this study, we carried out a numerical model test for the tidal flat ecosystem, using the pelagic system and the benthic system, simultaneously, in order to show a change in the tidal flat ecosystem. The flow of nitrogen, phosphorus and carbon has been identified as a primary consideration of marine ecosystem components, and the capability of water purification and the change of the tidal flat were predicted using this flow. In order to make a more reliable prediction, a field investigation to determine tide, current and creatures of the object coastal area has been done. The purification capability of this shallow-water region is estimated from the model results. According to the results of experiments, the tidal flat has a capability of water purification (Sink) of 11mgN/m2/day, but the other area has a load (Source) of 20mgN/m2/day. As a result, we could confirm that the tidal flat of an object coastal area plays an important role in water purification.

• Journal of Navigation and Port Research
• /
• v.30 no.1 s.107
• /
• pp.1-8
• /
• 2006

Recently, many ships such as VLCCs, dangerous cargo ships, high speed ferry boats are visiting Yeosu, Gwangyang harbor. The traffic volume of the year 2003 has increased as many as 2.5 times of 1988. However there is no suitable ships' routeing system which takes account of today's traffic situations in this area This study aims at the settling of hazardous factors to mitigate the danger to vessels in Yeosu${\cdot}$Gwangyang bay and to secure the safety of maritime environment.

• Journal of Environmental Science International
• /
• v.22 no.12
• /
• pp.1579-1587
• /
• 2013

This study was performed to evaluate the asbestos exposure levels and to calculate excess lifetime cancer risk (ELCR) for the risk assessment of the asbestos fibers released from asbestos-cement slate roofing (ASR) building. Total number of ASR buildings was into 21,267 in Busan, and 82.03 percent of the buildings was residential houses, and 43.61 percent of the buildings was constructed in 1970s. For this study, ten buildings were selected randomly among the ASR buildings. The range of airborne asbestos concentration in the selected ten ASR buildings was from 0.0016 to 0.0067 f/mL, and the concentration around no-admitted ASR buildings was higher than that around admitted buildings. The ELCR based on US EPA IRIS (integrated risk information system) model is within 3.5E-05 ~ 1.5E-04 levels, and the ELCR of no-admitted ASR buildings was higher than 1.0E-04 (one person per million) level that is considered a more aggressive approach to mitigate risk. These results indicate that the cancer risk from ASR buildings is higher than other buildings, and systematic public management is required for control of no-admitted ASR buildings within near future.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.7
• /
• pp.943-949
• /
• 2013

Recently, an electric vehicle (EV) has been become a huge issue in the automotive industry. The EV has many electrical units: electric motors, batteries, converters, etc. The DC distribution power system (DPS) is essential for the EV. The DC DPS offers many advantages. However, multiple loads in the DC DPS may affect the severe instability on the DC bus voltage. Therefore, a voltage bus conditioner (VBC) may use the DC DPS. The VBC is used to mitigate the voltage transient on the bus. Thus, a suitable control technique should be selected for the VBC. In this research, Current controller with fixed switching frequency is designed and applied for the VBC. The DC DPS consist of both a resistor load and a boost converter load. The load variations cause the instability of the DC DPS. This instability is mitigated by the VBC. The simulation results by Matlab simulink and experimental results are presented for validating the proposed VBC and designed control technique.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.4 no.1
• /
• pp.23-31
• /
• 2011

In this paper, the intelligent smart monitor system is implemented for the next generation vehicle. to mitigate the numerous effects of distractions within the vehicle, it is vital to put critical information where the driver can use it without affection focus on the road ahead. Audible alarms are useful supplements when used in conjunction with visual displays. But driving is an overwhelmingly visual task. To optimize a vehicle's active safety systems, more than just audible alarms are necessary. The driver needs a visual interface that focuses his or her attention on the road ahead. The most commonly viewed information in a vehicle is from the instrument cluster, where speed, tachometer, fuel, engine temperature, fuel gauge, turn indicators and warning lights provide the driver with an array of fundamental information. TFT LCD, LCD Back light led, plane mirror, lens and controllers parts were designed to intelligent integrated smart monitor system. Finally, in this paper, we analyze intelligent integrated smart monitor system for driver safety vehicles.

• Journal of Advanced Navigation Technology
• /
• v.20 no.4
• /
• pp.275-284
• /
• 2016

The potential impact of aircraft emissions on the current and projected climate of our planet is one of the more important environmental issues facing the aviation industry. Increasing concern over the potential negative effects of greenhouse gas emissions has motivated aircraft emission estimation and prediction as one of the ways to reduce aircraft emissions and mitigate the impact of aviation on climate. We obtained airline flight schedules for all the airports in Korea that are included in OAG data. Fuel burn and emission index of LTO flight which contains take off, climb and approach under 3000ft and Non LTO flight which contains climb, cruise and descent over 3000ft for all the airports in Korea in 2005 were estimated and analysed for each condition using AEIC software which has been developed by MIT Lab for Aviation and Environment.