• Advances in aircraft and spacecraft science
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• v.4 no.5
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• pp.529-541
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• 2017

Landing phase is one of the crucial and most important phases during robotic aerospace explorations. It concerns the impact of the landing module of a spacecraft on a celestial body. Risks and uncertainties of landing are mainly due to the morphology of the surface, the possible presence of rocks and other obstacles or subsidence. The present work quotes results of a computational analysis direct to investigate the stability during the landing phase of a lander on Phobos, a Mars Moon. The present study makes use of available software tools for the simulation analyses and results processing. Due to the nature of the system under consideration (i.e., large displacements and interaction between several systems), multibody simulations were performed to analyze the lander's behavior after the impact with the celestial body. The landing scenario was chosen as a result of a DOE (Design of Experiments) analysis in terms of lander velocity and position, or ground slope. In order to verify the reliability of the present multibody methodology for this particular aerospace issue, two different software tools were employed in order to emphasize two different ways to simulate the crash-box, a particular component of the system used to cushion the impact. The results show the most important frames of the simulations so as to provide a general idea about how lander behaves in its descent and some trends of the main characteristics of the system. In conclusion, the success of the approach is demonstrated by highlighting that the results (crash-box shortening trend and lander's kinetic energy) are comparable between the two tools and that the stability is ensured.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.216-219
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• 1997

We are developing a portable multipurpose gamma counting and imaging probe that will be useful for many applications in nuclear medicine including radioimmunoguided surgery in the detection and treatment of malignant tumors. Any diagnostic information provided by CT, MRI, PET, SPECT or gamma camera imaging prior to surgery obviously is very important, but current techniques are limited in many instances. To overcome some of these limitations, the portable multipurpose gamma probe is being developed. The gamma probe consists of NaI(Tl) crystal with 1" dia $\times$ 0.5" thick and singlechannel photomultiplier tube (SC-PMT) for counting, and 3" dia $\times$ 0.375" and multichannel photomultiplier tube (MC-PMT) for imaging, nuclear instrument module (NIM), position circuits, interface, and PC. The energy resolution using Tc-99m was measured as 14% and the spatial resolution using 3mm dia green LED was measured as 2.9mm. These priliminary results indicate that the currently developing probe is very promising and could be very useful for many applications in nuclear medicine.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1363-1372
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• 2011

Flooding based routing protocols are usually used to disseminate information in wireless sensor networks. Those approaches, however, require message retransmissions to all nodes and induce huge collision rate and high energy consumption. In this paper, HoGoP (Hop based Gossiping Protocol) in which all nodes consider the number of hops from sink node to them, and decide own gossiping probabilities, is introduced. A node can decide its gossiping probability according to the required average reception percentage and the number of parent nodes which is counted with the difference between its hop and neighbors' ones. Therefore the decision of gossiping probability for network topology is adaptive and this approach achieves higher message reception percentage with low message retransmission than the flooding scheme. Through simulation, we compare the proposed protocol with some previous ones and evaluate its performance in terms of average reception percentage, average forwarding percentage, and forwarding efficiency. In addition, average reception percentage is analyzed according to the application requirement.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.2
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• pp.86-91
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• 2004

PV power generation, which directly converts solar radiation into electricity, contains numerous significant advantages. It is inexhaustible and pollution-free, silent, contains no rotating parts, and has size-independent electricity conversion efficiency. The positive environmental effect of photovoltaics is that it replaces the more polluting methods of electricity generation or that it provides electricity where none was available before. This paper highlights a novel simple method to abstract the entire parameters of the solar cell. In development, design and operation of PV power generation systems, a technique for constructing V-I curves under different levels of solar irradiance and cell temperature conditions using basic characteristic values of the PV module is required. Everyone who has performed manual acquisition and analysis of solar cell I versus V data would agree that the job is tedious and time-consuming. A better alternative is to use an automated curve tracer to print out the I versus V curves and compute the four major parameters; $V_{oc}$, $I_{sc}$, FF, and . Generally, the V-I curve tracer indicates only the commonly used solar cell parameters. However, with the conventional V-I curve tracer it is almost impossible to abstract the more detailed parameters of the solar cell; A, $R_{s}$ and $R_{sh}$ , which satisfies the user, who aims at the analysis of the development of the PV power generation system, that being advanced simulation. In this paper, the proposed method provides us with satisfactory results to enable us to abstract the detailed parameters of the solar cell; A, $R_s$ and $R_{sh}$.>.

• Journal of Korean Society of Steel Construction
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• v.30 no.2
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• pp.77-85
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• 2018

A through diaphragm is often used to ensure their stiffness for moment-resisting connections using rectangular steel-tube column and H-shaped beam. The through-diaphragm connections, however, have some difficulties for their applicabilities to the field due to the complexity of the fabrication and construction processes. This study thus proposes a new modular system of steel structures assembled only using bolts without welding, by bringing a connection module composed of rectangular steel-tube column, H-shaped beam and oneway bolt onto the site. An experimental study to evaluate the seismic performance of the proposed connection details based on the new modular system is then conducted. The length and type of the inner reinforcement plate are considered as the primary design parameters, and the strength, stiffness, ductility and energy dissipation capability of the new connections are experimentally analyzed by comparison to those of conventional through diaphragm connections.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.430-433
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• 2017

This paper presents a S/C/X-band LNA MMIC with resistive feedback structure in 0.25 um GaN HEMT process. The GaN devices have advantages as a high output power device having high breakdown voltage, energy band gap and stability at high temperature. Since the receiver using the GaN device with high linearity can be implemented without a limiter, the noise figure of the receiver can be improved and the size of receiver module can be reduced. The proposed GaN LNA MMIC based on 0.25 um GaN HEMT device is achieved the gain of > 15 dB, the noise figure of < 3 dB, the input return loss of > 13 dB, and the output return loss of > 8 dB in the S/C/X-band. The current consumption of GaN LNA MMIC is 70 mA with the drain voltage 20 V and the gate voltage -3 V.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.207-213
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• 2014

In this paper, we propose Bluetooth based on efficient indoor-emotion-lighting control system. The proposed Bluetooth based on indoor-emotion-lighting control system was designed to be automatically controlled by the motion sensor light and using a Bluetooth module may be controlled to light up or mobile PC, wall pad. In addition, It was designed the LED lighting On/Off control the environment according to Humidity, the temperature, illumination, motion sensors. System based on the bluetooth is automatic control possible using the illumination sensor, and by selecting the desired lighting partial control can be designed. The experimental efficiency results of the proposed indoor-emotion-lighting control system were designed to provide an internal environment adapted to a resident, were able to maximize the energy savings, have reduced power consumption than the traditional simple On/Off control system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.385-390
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• 2005

LMTT (Linear Motor-based Transfer Techn-ology) is a horizontal transfer system for the yard automation, which has been proposed to take the place of AGV (Automated Guided Vehicle) in the maritime container terminal. The system is based on PLMSL (Permanent Magnetic Linear Synchronous Motor) that consists of stator modules on the rail and shuttle car. It is desirable to reduce the weight of LMTT in order to control the electronic devices with minimum energy. In this research, the DACE modeling, known as the one of Kriging interpolation, is introduced to obtain the surrogate approximation model of the structural responses. Then, the GRG(Generalized Reduced Gradient) method built in Excel is adopted to determine the optimum. The objective function is set up as weight. On the contrary, the design variables are considered as transverse, longitudinal and wheel beam's thicknesses, and the constraints are the maximum stresses generated by four loading conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.708-717
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• 2017

Tracking of sound-location is widely used in various area such as intelligent CCTV, video conference and voice commander. In this paper we introduce the real-time sound-location tracking method for smart lecture system using TDoA(Time Difference of Arrival) with orthogonal microphone array on the ceiling. Through discussion on some models of TDoA detection, cross correlation method using linear microphone array is proposed. Orthogonal array with 5 microphone could detect omni direction of sound-location. For real-time detection we adopt the threshold of received energy for eliminating no-voice interval, signed cross correlation for reducing computational complexity. The detected azimuth angles are processed using median filter for lowering the angle deviation. The proposed system is implemented with high performance MCU of TMS320F379D and MEMs microphone module and shows the accuracy of 0.5 and 6.5 in degree for white noise and lectured voice, respectively.

• KIEAE Journal
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• v.14 no.1
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• pp.67-74
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• 2014

There have distinctly been no the installation criteria and maintenance management of BIPV systems, although the BIPV market is consistently going on increasing. In addition, consideration of the BIPV generation quantity which has been installed at several diverse places is currently almost behind within region in Korea. Therefore, the main aim of this study is to evaluate the BIPV generation and to be base data of reducing rate depending on regional installation angles using PVpro which was verified by measured data. Various conditions were an angle of inclination and azimuth under six major cities: Seoul, Daejeon, Daegu, Busan, Gwangju, Jeju-si for the BIPV system generation analysis. As the results, Seoul showed the lowest BIPV generation: 1,054kWh/kWp.year, and Jeju-si have 5percent more generation: 1,108.0kWh/kWp.year than Seoul on horizontal plane. Gwangju and Daejeon turned out to have similar generation of result, and Busan showed the highest generation: 1,193.5kWh/kWp.year, which was increased by over 13percent from Seoul on horizontal plane. Another result, decreasing rate of BIPV generation depending on regional included angle indicate that the best position was located on azimuth: $0^{\circ}$(The south side) following the horizontal position(an angle of inclination: $30^{\circ}$). And the direction on a south vertical position(azimuth: $0^{\circ}$, an angle of inclination: $90^{\circ}$) then turned out reducing rate about 40percent compared with the best one. Therefore, these results would be used to identify the installation angle of the BIPV module as an appropriate position.