• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.947-954
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• 2009

This paper proposed a new balanced power amplifier using the reflected input of conventional balanced power amplifiers composed of branch line hybrid coupler. In general, the single-ended amplifier in balanced amplifiers does not have the perfect matching, so the reflected input power, in other words the leakage power, is terminated conventionally at the isolation port of hybrid coupler. However in this work, the leakage power is injected into the auxiliary amplifier, and its output power is combined to the output power of balanced amplifier. Therefore output power, efficiency, and 2-tone IMD3 performances of the proposed balanced amplifier are highly improved compared to the conventional balanced amplifier. For the verification of the proposed balanced amplifier, a conventional balanced amplifier and the proposed balanced amplifier are designed, fabricated and measured, and the measured results are compared. The proposed balanced amplifier shows the improvement in the output power(Pout), power added efficiency (PAE), and 2-tone IMD3 by 3dB, 5.2%, and $5{\sim}10dBc$, respectively, from the measurement.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.37-44
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• 2016

Optical fiber temperature sensing systems have incomparable advantages over traditional electrical-cable-based monitoring systems. However, the fiber optic interrogators and sensors have often been rejected as a temperature monitoring technology in real-world industrial applications because of high cost and over-specification. This study proposes a multiplexed fiber optic temperature monitoring sensor system using an economical Optical Time-Domain Reflectometer (OTDR) and Hard-Polymer-Clad Fiber (HPCF). HPCF is a special optical fiber in which a hard polymer cladding made of fluoroacrylate acts as a protective coating for an inner silica core. An OTDR is an optical loss measurement system that provides optical loss and event distance measurement in real time. A temperature sensor array with the five sensor nodes at 10-m interval was economically and quickly made by locally stripping HPCF clad through photo-thermal and photo-chemical processes using a continuous/pulse hybrid-mode laser. The exposed cores created backscattering signals in the OTDR attenuation trace. It was demonstrated that the backscattering peaks were independently sensitive to temperature variation. Since the 1.5-mm-long exposed core showed a 5-m-wide backscattering peak, the OTDR with a spatial resolution of 40 mm allows for making a sensor node at every 5 m for independent multiplexing. The performance of the sensor node included an operating range of up to $120^{\circ}C$, a resolution of $0.59^{\circ}C$, and a temperature sensitivity of $-0.00967dB/^{\circ}C$. Temperature monitoring errors in the environment tests stood at $0.76^{\circ}C$ and $0.36^{\circ}C$ under the temperature variation of the unstrapped fiber region and the vibration of the sensor node. The small sensitivities to the environment and the economic feasibility of the highly multiplexed HPCF temperature monitoring sensor system will be important advantages for use as system-integrated temperature sensors.

• Journal of Korea Multimedia Society
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• v.23 no.11
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• pp.1388-1395
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• 2020

Daily monitoring of the heart rate can facilitate detection of heart-related diseases in their early stages. Therefore, providing an easy-to-use and noninvasive heart rate monitoring system has been a very popular research topic in the field of healthcare. One of good candidate methods is to use commonly available cameras and extract information that can help to estimate heart rate from a human face. Generally, such information can be retrieved using two different approaches: photoplethysmography (PPG) and ballistocardiography (BCG). PPG exploits slight color changes caused by blood volume variations during heartbeats; thus, it tends to be vulnerable to unstable lighting conditions. BCG exploits subtle head motions caused by pumped blood travelling through the carotid artery during heartbeats; thus, it is vulnerable to the voluntary head movements that are not related to heartbeats. Nevertheless, most related works use either to estimate the heart rate. In this paper, we propose to combine two approaches to be robust to challenging conditions. Specifically, we explore possible ways to combine raw signals obtained from two approaches and verify that the proposed combination shows better accuracies under challenging conditions, such as voluntary head movements and ambient lighting changes.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.3
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• pp.485-491
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• 2014

The study of Web MGIS(Marine Geographic Information System) based on the SVG(Scalable Vector Graphics) is mainly performed on effective methodologies which transform real world data to computing world data. Web GUI system has its own target on reliable data service by acquisition of geometric information using HYCOM(HYbrid Coordinate Ocean Model), accurate measurement and graphical visualization. This type of raw data visualization can be built without software tools, yet is incredibly useful for interpreting and communicating data. Even simple visualizations can aid in the interpretation of complex hydrodynamic relationships that are frequently encountered in the marine environment. The Web MGIS provides an easy way for hydrodynamic geoscientists to construct complex visualizations that can be viewed with free software. This study proposes a Web GUI MGIS using FVCOM(Finite Volume Coastal Ocean Model). Finally, we design a Marine Web GUI system of Kosrae Coastal Waters integrating above data models. It must adds more ecological information and the various service item for approach more easily in order to user.

• The Journal of the Korea Contents Association
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• v.3 no.2
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• pp.24-30
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• 2003

Pre-existing authentication system such as token based method, knowledge-based and hybrid method have problems such as loss and wiretapping. for this, this paper describes the biometric authentication system which have the excellent convenience and security. In particular, a new biometric system by human face biometric features which have the non-enforcement and non-touch measurement is proposed. Firstly, facial features are extracted by Y- histogram and tilted face images we corrected by coordinate transformation and scaling has done for achieving independent of the camera positions. Secondly, feature vectors are extracted such as distance and intersection angles and similarities we measured by fuzzy relation matrix. finally, the effectiveness of this paper is demonstrated by experiments.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.1
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• pp.1-9
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• 2016

In this paper, for the improvement of quality of service(QoS) performance of heterogeneous networks, multi-cell scheduling is proposed. In order to implement the proposed algorithm, for the recognition of the impact on the throughput performance of users, macro-pico-cells that form distributed architecture were proposed. In operating heterogeneous networks, considering the centralized structure, a macro-RRH(Remote Radio Head) deployment scenario was proposed. For interference mitigation of the proposed system, by applying the optional sub-frame, through CQI(Channel Quality Indicator) measurement for each sub-frame period, constraint conditions were measured according to system situations. For the simplification, the pattern of the same ABS muting was assumed. In the above two multi-cell environments, the algorithm of high-speed load balancing maintenance was proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.424-427
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• 2002

In this papaer, there is a basic research for the development of the Hybrid digital radiation detector with a new system, make up for existing digital radiation detector of direct/indirect method with a weak point. for enhance the efficiency characteristics of signal response from X-ray detector using the a-Se, We make sample with various kinds of layer, through the ratio of As(0.l%,0.3%,0.5%,1%,1.5%,5%,10%). We measure net charge with a leakage current and photo current for electric charateristics. Ratio of As in a-Se consist of 7 stage, It made of using the thermal deposition system, In the made of samples, we made multi layer using the EFIRON optical adhesives from phosphor layer consist of Oxybromide$(BrO_2)$. As a result of X-ray measurement, the best result is ; leakage current(0.30nA/cm2), net charge(610.13pC/cm2/mR) when the condition is voltage(9V/um), 0.3% ratio of As in multi layer(BrO2 + a-Se)

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.50-51
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• 2012

The final purpose of this study is to develop a hybrid ocean power generation system which has innovate and very high efficiency performance, and which can be operated on both emergency and normal conditions. So, A survey on the electricity power consumption of residential areas at island on south coast.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2402-2409
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• 2009

This paper proposed a simple and helpful analysis model of voltage variation in order to predict the voltage variation at PCC (Point of Common Coupling), when a wind turbine is connected in an isolated grid. The PCC voltage flucuates when the wind turbine outputs active power to an isolated grid. This voltage variation is proportional to the product of the line impedance from the ideal generator to the PCC and the wind turbine output current. And It is different according as where wind turbine is connected. To solve the problem of voltage variation, this paper proposed the reactive power control. To verify the proposed analysis model, this paper utilized PSCAD/EMTDC Simulation and the field measurement data of the voltage variation during the wind power generation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.155-157
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• 2009

3성분계 Ti-Si-N코팅은 $N_2$와 Ar 혼합가스 분위기하에서 Ti 소스는 아크 이온 플레이팅, Si 소스는 직류 마그네트론 스퍼터링 증착기법을 이용해 스테인리스 스틸 기판위에 합성되었다. Ti-Si-N 코팅에서 Si 함유량이 증가함에 따라 주상정 구조가 TiN 나노결정질을 $SiN_x$ 비정질이 둘러싸고 있는 독특한 나노복합체구조로 변화되었다. 상온 NaCl 3wt% 용액에서 Anodic Polarization measurement 법으로 측정된 결과에서 Si 함유량이 높아짐에 따라 나노복합체 구조로 인하여 더 우수한 내식성을 나타내었다.