• Resources Recycling
• /
• v.10 no.3
• /
• pp.14-22
• /
• 2001

For the recycle of coal fly ash generated from power stations, we developed an electrocyclone system which can separate unburned carbon form coal fly ash, based on the fact that coarse fly ash particles contain higher amount of unburned carbon and unburned carbon particles are charged positively, and pure ash particles are charged negatively on contacting each other. Additionally, guide vanes were installed in the cyclone to control the cut size. Two types of electrode, stick and grid type, were designed to investigate the effect of electrode type. Results show that by introducing an electric field inside the cyclone, the yield increases by 5 to 15e1o. But the content of unburned carbon in the clean ash does not change significantly.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.10
• /
• pp.971-977
• /
• 2012

It is well known that the performance of a diesel injector is directly related to the power, emission, and fuel consumption of the diesel combustion engine. In this study, the injection response characteristics of CRDi injectors driven by a solenoid coil and a piezoceramic were investigated by using the AMESim simulation code. Some analytical parameters such as the fuel pressure and hole diameter were considered. From this study, it was shown that the piezo-driven injector had a faster response and had better control capability than the solenoid-driven injector. In addition, it was found that the piezo-driven injector can be utilized more effectively in a multiple injection scheme than a solenoid-driven injector.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.4
• /
• pp.402-407
• /
• 2013

In this paper, we consider an interference scenario and interference simulation method of intra-wireless vessel communications using SEAMCAT (Spectrum Engineering Advanced Monte-Carlo Analysis) simulator. The interference between electromagnetic equipment and low power radio apparatus can deteriorate a stability of vessel system and it is necessary to analyze the interference probability between radio devices. The proposed simulation method in the 13.56MHz ISM frequency band shows that the interference effect can be minimized when the distance between the devices is greater than 4.7m and 2.7m in case that the victim receiver (VR) are RFID and remote control(RC) toy, respectively. The proposed interference scenario and simulation method are expected to be helpful in the interference probability analysis and regulation policy in the ISM frequency band.

• Journal of Society of Preventive Korean Medicine
• /
• v.16 no.1
• /
• pp.1-13
• /
• 2012

The objective of this study is to discuss the role of integrative medicine (IM) in contemporary health care settings, and how and which factors affect and facilitate the success of IM in terms of the integration of complementary and alternative medicine (CAM) and conventional medicine in primary health care (PHC). IM is meant to provide the best possible health care, for both patient and physician. The way of IM use in the developed countries presents various ways that IM can be provided, and it appears that strategies have been successfully developed to facilitate integration. Although few of the barriers to the integration of CAM and conventional medicine have been resolved, concerns over the legitimacy of CAM in health care (e.g., safety, biomedical evidence, and efficacy) are being overcome by the use of evidence-based practice in IM delivery. There are dominant models of IM that have been developed. The model types signify different levels of equity between CAM and conventional medicine in regard to the power, autonomy, and control held by each. However, the factors common to all IM models, whether describing CAM as supplementary or complementary to conventional medicine, is the concept of a health care model that aspires to be client-centred and holistic, with focus on health rather than disease as well as mutual respect among peer practitioners. Finally, this study concluded that the growth and viability of traditional Korean medicine(TKM) depend on evidence-based practices and identifying the successful influences on the integration of TKM and conventional medicine for recognition of its inherent value in PHC. Some recommendations for the integration of TKM and conventional medicine were suggested.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.1
• /
• pp.148-156
• /
• 2014

The objective of this study is to compare NOx emissions from light duty diesel vehicles measured from on-road tests that conducted under various driving routes and seasonal conditions. We measured real-driving NOx emissions using PEMS, portable emissions measurement system, under the urban, rural and motorway road traffic conditions. On-road tests were repeated at summer, fall and winter season. The accumulated driving distance is more than 1,200 km per each vehicle. Route average NOx emission factors were compared among nine route-season combinations. The emission characteristics of each combinations were investigated using time series mass emission rates and vehicle operation-based emission rates and activities, which is based on U.S. EPA's MOVES model. Most concerned route-season combination is "urban road condition at summer", which shows two to eleven times higher NOx emissions than other combinations. The emission rates and activities under low speed operating conditions should be managed in order to reduce urban-summer NOx. From a NOx control strategy perspective, the exhaust gas recirculation, EGR, is observed to be properly operated under wide range of vehicle driving conditions in Euro-5 vehicles, even if the air conditioner turns on. In high power demanding conditions, the effect of overspeeding could be more critical than that of air conditioner activation.

• Journal of Information Technology and Architecture
• /
• v.11 no.1
• /
• pp.53-62
• /
• 2014

The research tries to find appropriate nations and cities of the international supporting centers according to Korean firms' requests. It also tries to find out proper designs of governance structure and strategic and operational control system of the center. Two methods are used to find out Korean firms' requests. One is the expert interviews and the other is the questionnaire survey. The email survey is sent to 120 firms of IT service, package software, telecom facilities and broadcasting equipment industries. Their opinions in addition to interview results are used as a basis of selecting potential regions for new centers and types of their services. According to survey results, southeast asia is the most preferred region and Indonesia, Vietnam, Thailand, Malaysia and Singapore are selected as potential nations for a location of the center in southeast asia. However, the survey result is not fully agreed with the interviewees' opinions. The interviewees tell that there are not much demand in nations with low purchasing power and low IT industry level. That is, Indonesia and Vietnam are not proper places for the centers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.6A
• /
• pp.601-608
• /
• 2011

In OFDMA(Orthogonal Frequency Division Multiple Access) based multi-hop networks, the subcarrier-pairing scheme using the SNR(Signal-to-Noise Ratio) has been proposed as the best solution. But, this scheme is not optimal in cognitive radio system, because of the power control due to the interference to the primary user. In this paper, we propose two subcarrier-pairing schemes for OFDMA based 2-hop cognitive radio systems. One is the IT(Interference channel gain) scheme considering only the interference channel gain, and the other is the CI(Channel SNR over interference channel gain) scheme considering the ratio of channel SNR to interference channel gain. The results show that the CI scheme has the best performance in which throughput is improved more than 10% in comparison with other schemes.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1996.06a
• /
• pp.40-41
• /
• 1996

Nitridation technique has been receiving much attention for the formation of a thin nitrided buffer layer on which high quality nitride films can be formedl. Particularly, gallium nitride (GaN) has been considered as a promising material for blue-and ultraviolet-emitting devices. It can also be used for in situ formed and stable passivation layers for selective growth of $GaAs_2$. In this work, formation of a thin nitrided layer is investigated. Nitrogen electron cyclotron resonance(ECR)-plasma is employed for the formation of thin nitrided layer. The plasma source used in this work is a compact ECR plasma gun3 which is specifically designed to enhance control, and to provide in-situ monitoring of plasma parameters during plasma-assisted processing. Microwave power of 100-200 W was used to excite the plasma which was emitted from an orifice of 25 rnm in diameter. The substrate were positioned 15 em away from the orifice of plasma source. Prior to nitridation is performed, the surface of n-type (001)GaAs was exposed to hydrogen plasma for 20 min at $300{\;}^{\circ}C$ in order to eliminate a native oxide formed on GaAs surface. Change from ring to streak in RHEED pattern can be obtained through the irradiation of hydrogen plasma, indicating a clean surface. Nitridation was carried out for 5-40 min at $RT-600{\;}^{\circ}C$ in a ECR plasma-assisted molecular beam epitaxy system. Typical chamber pressure was $7.5{\times}lO^{-4}$ Torr during the nitridations at $N_2$ flow rate of 10 seem.(omitted)mitted)

• Plant Journal
• /
• v.9 no.2
• /
• pp.42-45
• /
• 2013

The worldwide issue of greenhouse gas reduction has recently drawn great attention to carbon capture and storage(CCS). In this study, we developed a 10,000 ton/year pilot injection plant for geological storage of carbon dioxide. Major components of the pilot plant include a pressure pump, a booster pump, and an inline heater to bring liquid carbon dioxide into its supercritical state. The test results show that the pilot plant readily achieves the injection pressure and temperature, showing satisfactory control performance. The overall power consumption is 2,000 ~ 2,500 W, more than 75% of which consumed by the pressure pump. This study will facilitate varied research on greenhouse gas reduction as the only domestically developed system for geological injection.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1328-1333
• /
• 2005

This paper presents the temperature-pressure characteristics of a new SMH actuator using a Peltier module. The SMH actuator is characterized by its small size, low weight, noiseless operation, and compliance similar to that of the human body. The simple SMH actuator, consisting of the plated hydrogen-absorbing alloys as a power source, Peltier elements as a heat source, and a cylinder with metal bellows as a functioning part has been developed. To improve the thermal conductivity of the hydrogen-absorbing alloy, an assembly of copper pipes has been used. It is well known that hydrogen-absorbing alloys can reversibly absorb and desorb a large amount of hydrogen, more than about 1000 times of their own volume. The hydrogen equilibrium pressure increases when hydrogen is desorbed by heating of the hydrogen-absorbing alloys, whereas by cooling the alloys, the hydrogen equilibrium pressure decreases and hydrogen is absorbed. The new special metal hydride (SMH) actuator uses the reversible reaction between the heat energy and mechanical energy of a hydrogen absorbing alloys. The desirable characteristics of SMH actuator, which makes it suitable for the uses in medical and rehabilitation applications, have been also studied. For this purpose, the characteristics of the new SMH actuator for different temperature, pressure, and external load were explored.