• KIEAE Journal
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• v.15 no.4
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• pp.69-76
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• 2015

Purpose: This study is to investigate the effects of facade insulation and window remodeling of an existing old middle school building on the reduction of energy consumption. Method: To analyze energy performance of building, using DesignBuilder v3.4, building energy simulation tool based EnergyPlus engine. Energy consumption and problem of target building was analyzed based on data and survey. Based on building energy simulations it analyzed the variation of energy demand for the building according to U-value of wall, glazing properties and external shading devices. Result: When insulation of building was reinforced, cooling and heating load was decreased. Glazing properties that minimize cooling and heating energy consumption were analyzed. In conclusion, it is important to choose SHGC and U-value of window fit in characteristic of target building. Setting external blind for cooling load decreases 5%.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.544-557
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• 2010

This paper addresses the problem of controlling the envelope's power peak of single carrier modulated signals, band limited by root-raised cosine (RRC) pulse shaping filters, in order to reduce power amplifier back-off for very small aperture terminals ground stations. Magnitude modulation (MM) is presented as a very efficient solution to the peak-to-average power ratio problem. This paper gives a detailed description of the MM concept and its recent evolutions. It starts by extending the look-up-table (LUT) based approach of the MM concept to M-ary constellations with M ${\leq}$ 16. The constellation and RRC symmetries are explored, allowing considerable reduction on LUT computation complexity and storage requirements. An effective multistage polyphase (MPMM) approach for the MM concept is then proposed. As opposed to traditional LUT-MM solutions, MM coefficients are computed in real-time by a low complexity multirate filter system. The back-off from high-power amplifier saturation is almost eliminated (reduction is greater than 95%) with just a 2-stage MPMM system even for very demanding roll-off cases (e.g., ${\alpha}$ = 0,1). Also, the MPMM is independent of modulation in use, allowing its easy application to constellations with M > 16.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.270-279
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• 2014

The Viterbi decoding algorithm, which provides maximum - likelihood decoding, is currently considered the most widely used technique for the decoding of codes having a state description, including the class of linear error-correcting convolutional codes. Two classes of nonbinary convolutional codes are presented. Distance preserving mapping convolutional codes and M-ary convolutional codes are designed, respectively, from the distance-preserving mappings technique and the implementation of the conventional convolutional codes in Galois fields of order higher than two. We also investigated the performance of these codes when combined with a multiple frequency-shift keying (M-FSK) modulation scheme to correct narrowband interference (NBI) in power-line communications channel. Themodification of certain detectors of the M-FSK demodulator to refine the selection and the detection at the decoder is also presented. M-FSK detectors used in our simulations are discussed, and their chosen values are justified. Interesting and promising obtained results have shown a very strong link between the designed codes and the selected detector for M-FSK modulation. An important improvement in gain for certain values of the modified detectors was also observed. The paper also shows that the newly designed codes outperform the conventional convolutional codes in a NBI environment.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.2
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• pp.35-43
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• 2013

The green building is one of biggest factors to go the goal of energy saving and environmental conservation, "reduction of energy consumption, friendly energy technology, recycling of resource, and environmental pollution reduction technology. The purpose of these green buildings realized by the energy-saving technology such as the thermal bridge breaker(or thermal bridge block). Thermal bridges are localized elements that penetrate insulated portions of building envelope that results in heat loss. The purpose of this paper is to describe the technical interactions for patents of a thermal bridge breaker(TTB) used in green building practices, and be subject to investigation to TTB in the leading countries, that is, United State, Europe Union, Japan, and Korea. As a result, there are four TTB categories(roof, wall-slab connection, opening, footing) in house or building. The TTB categories is remarkable technology that is apparatus in slab-wall joints and sealing element of opening frame in walls.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.164-175
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• 1997

In this paper, the CE-OQPSK that has constant envelope was designed for applying PSK to the nonlinear amplifier so as to improve power efficiency. For this realization. ROM and D/A converter that have relative low power consumption were used. As a result of comparing the PSD (Power spectrum density) of CE-OQPSK with that of conventional OQPSK through simulation for estimating the performance. In case of correlation factor ${\alpha}$ = 0.707. the improvement of bandwidth efficiency of 5% and 20% is achieved in the main lobe and the sidelobe, respectively. And, in case additional bandwidth-limiting-filter is added, it can be shown that the PSD of CE-OQPSK meet the FCC wireless LAN spectrum specification.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.382-388
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• 2017

In this study, a basic study was carried out on the external strengthening method of public buildings. A steel damper is installed outside the specimen with a rocking wall and connected to the frame. Two specimens were fabricated, and the non-reinforced specimens utilized the existing results. As a result of evaluating the envelope curve, strength, stiffness and energy dissipation capacity, it was evaluated that the strength enhancement of the RW_P specimen externally reinforced plate damper was evaluated to be excellent. In addition, RW_S specimens with external S type damper shows a gentle envelop curve after maximum load, and it can be confirmed that the damper properly dissipates the seismic energy.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.1-6
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• 1984

This paper describes that the compensation of frequency dependent attenuation (F.D.A.) and faithful envelope detection using the analytic signal magnitude (A.S.M.) improve the range resolut ion in an acoustic medium. It is shown that a mean of computing the magnitude of. analytic signal is better than that of conventional A-mode. In addition, this proposed method is much easier than the above methods to detect two closely spaced interfaces on the A-mode. As the result of experiment, we obtained range resolution of 0.5 mm with transducer of 3.5 MHz. This method can be applied to medical experiment, diagonostic and nondestructive testing.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.8 s.111
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• pp.707-712
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• 2006

In this paper, dual bias control circuit and PBG(Photonic BandGap) structure have been employed to improve PAE(Power Added Effciency) of the Doherty amplifier on Input power level. The gate and drain bias voltage has been controlled with the envelope of the input RF signal and PBG structure has been employed on the output port of Doherty amplifier. The proposed Doherty amplifier using dual bias controlled circuit and PBG has been improved the average PAE by 8%, $IMD_3$ by -5 dBc. And proposed Doherty amplifier has a high efficiency more than 30% on overall input power level, respectively.

• Journal of electromagnetic engineering and science
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• v.15 no.4
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• pp.219-223
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• 2015

In this paper, a miniaturized radio frequency choke (RFC) using modified stubs is proposed to improve isolation characteristics in a multiple-input-multiple-output (MIMO) antenna system. The proposed RFC, based on the LC resonance, is designed to suppress the leakage current that leads to the degradation of antenna diversity performances in the MIMO antenna configuration. The proposed RFC is composed of two open stubs that are implemented on the top of the ground plane and miniaturized by adding a slit structure on the ground plane. The MIMO antennas are also designed to verify isolation performance in the LTE 2300 band (2,300-2,400 MHz). The MIMO antennas perform well with low reflection coefficient characteristics and high isolation characteristics in the whole LTE 2300 band. To evaluate the isolation in the MIMO system, the envelope correlation coefficient (ECC) is calculated, and the value is less than 0.08. The achieved ECC is regarded as a reasonable result for improving isolation performance in the frequency range of 2,300-2,400 MHz; also, radiation patterns of antenna elements are maintained regardless of the presence of RFC.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.55.2-55.2
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• 2012

Silicate-carbon stars are characterized by oxygen-rich (O-rich) dust features despite their carbon-rich (C-rich) photospheres. While the origin of silicate-carbon stars has been a mystery ever since their discovery, the most widely accepted hypothesis is that the silicate-carbon stars have a low-luminosity companion and the O-rich material is stored in a circumbinary disk or a circumstellar disk even after the primary star becomes a carbon star. In order to study the properties of circumstellar dust envelopes of silicate-carbon stars, we perform radiative transfer model calculations using RADMC-3D with an axi-symmetric dust density distribution (a disk) as well as a spherically symmetric dust distribution. For various dust envelope models with different shapes and chemistry, we calculate the model spectral energy distributions (SEDs) and compare the model results with the observed SEDs of selected 5 silicate-carbon stars. The Circumstellar disk models are fairly well fitted with the observational data of 5 silicate-carbon stars. We find some evidences that the circumbinary disk model could be a better explanation for the origin of silicate carbon stars than the simple detached silicate dust shell model of the transition phase of the stellar chemistry.