• Land and Housing Review
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• v.8 no.4
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• pp.257-266
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• 2017

LH has been using ultra high strength reinforcing bars (SD500 and SD600), since 2011. Such a change requires an adjustment of the old extra rates of bar splice to reflect use of ultra high strength reinforcing bars, as these rates had been set based on SD400 bars. It is particularly difficult to calculate precisely rebar lap-splice locations for large areas, such as those in apartment buildings. This research aims to adjust the extra rates of bar splice to reflect a reasonable rate; the rebar lap-splice length is not an exact estimation, but instead, an extra rates of bar splice is set and the rebar lap-splice length is increased by 2% (D 10) - 7% (025) depending on the bar size. The subjects of this study are LH apartments undergoing frame construction. We studied the quantity estimations from the design drawings, and analyzed the settlement quantities of construction field. The results of the study revealed that, when each of the quantities are analyzed, consider adjusting the extra rates of bar splice of some rebar to 1% - 3.5%. This was caused by an overuse of reinforcing bars in onsite construction and the use of supporting bars that have not been reflected in the documents, among other reasons. Based on the results of our study, an improvement plan for the current extra rates of bar splice seems to be necessary, cutting or raising the rate depending on the analysis of the data. Through this study, we expect to contribute to the calculation of reasonable construction costs, improvements in the quality of rebar work, and improvements in the capacity of design techniques for apartment buildings.

• Journal of KIISE:Information Networking
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• v.41 no.4
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• pp.151-166
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• 2014

The present method of measuring QoE (Quality of Experience) was to measure the whole block from the server that provides service to the terminal that the client gets the service. In this way, it was possible to simply determine whether the quality of QoE was good or not, and when the quality of QoE became bad, there was no way of presenting solutions. Also, as QoE metrics are numerous, there has been no strict regulation on how to use. This study analyzed QoE metrics in the viewpoints of network and clients, subdivided the whole service into three phases including one from the server providing the service to the router, another from the router to the terminal getting the service, and the third from the service router to the client router, and presented QoE metric frames appropriate for each phase. Through this, in the KOREN-CERNET environment, this study designed and embodied QoE network and demonstrated stability of QoE network, reduction in client complaint settlement time, and content adjustment effect according to the network change.

• Journal of Powder Materials
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• v.23 no.4
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• pp.311-316
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• 2016

$Ni(OH)_2$ hollow spheres have been prepared by solvent displacement crystallization using a micro-injection device, and the effect of process parameters such as concentration and the relative ratio of the injection speed of the precursor solution, which is an aqueous solution of $NiSO_4{\cdot}6H_2O$, to isopropyl alcohol of displacement solvent have been investigated. The crystal phases after NaOH treatment are in the ${\beta}-phase$ for all process parameters. A higher concentration of $NiSO_4{\cdot}6H_2O$ aqueous solution is injected by a micro-injection device and bigger $Ni(OH)_2$ hollow spheres with a narrower particle size distribution are formed. The crystallinity and hardness of the as-obtained powder are so poor that hydrothermal treatment of the as-obtained $Ni(OH)_2$ at $120^{\circ}C$ for 24 h in distilled water is performed in order to greatly improve the crystallinity. It is thought that a relative ratio of the injection speed of $NiSO_4{\cdot}6H_2O$ to that of isopropyl alcohol of at least more than 1 is preferable to synthesize Ni(OH)2 hollow spheres. It is confirmed that this solution-based process is very effective in synthesizing ceramic hollow spheres by simple adjustment of the process parameters such as the concentration and the injection speed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.3
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• pp.225-231
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• 2011

The satellite clock anomalies, one of the abnormal signal factors of the GPS satellites, can have a significant impact on the GPS measurements. However, it can be difficult to detect the anomalies of the satellites clock before the range of the satellites clock error becomes bigger than the range of the other factors, due to the measurement including error of the orbit, ionosphere delay, troposphere delay, multipath and receiver clock. In order to perform quick and accurate detection by minimization of critical range in anomalies of the satellites clock, this paper suggested a solution to detect precise anomalies of the satellites clock after application of carrier smoothing filter from measurement by dual-frequency and adjustment of errors which can be occurred by other factor and the receiver clock errors. The performance of the proposed method was confirmed by comparing to the satellite clock biases which are provided by IGS.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.2
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• pp.74-81
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• 2002

In general, a multipath generator consists of a time delay generator, phase rotator, and amplitude attenuator, and is implemented mostly in an analog manner. Analog, or partially analog versions of a multipath generator is disadvantageous in that they may suffer from problems associated with component aging and adjustment, signal fidelity degradation stemming from repeated A/D and D/A conversion use of high frequency to achieve fine i.e., subsample fractional tin delays. This paper presents the design and implementation methodology of a full digital multipath generator which can be used in performance evaluations of digital terrestrial television as well as communications, receivers. In particular, an efficient practical method is proposed which can achieve both integer and fractional time delays simultaneously, without placing restrictions on the allowable system master clock frequency. The proposed algorithm lends itself to minimizing hardware implementation cost by relegating some fixed put of the computation involved to an IBM PC. The proposed multipath generator occupies only a single digital board space, and its experimental results are provided to corroborate the proposed implementation methodology.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.544-547
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• 2006

A time-domain modeling approach is used to study characteristics of a widely tunable coupled-ring reflector (CRR) laser diode(LD). The CRR consists of a bus waveguide and two coupled ring resonators coupled to the bus without resorting to distributed Bragg grating structure. The tuning range can be a few tens of nanometers with a side mode suppression ratio exceeding 35dB through the adjustment of currents into the phase control sections in the rings. The CRR laser diode has long effective cavity length compared to conventional laser diodes. Accordingly, a broad additional resonance peak in the amplitude modulation characteristics is observed between 20 to 30 GHz, implying the extension of amplitude modulation bandwidth.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.7
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• pp.30-38
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• 2012

This paper presents packet detection, frequency offset estimation architecture and performance analysis for OFDM-based wireless personal area network (WPAN) systems. Packet detection structure is used to find the start point of a packet exactly in WPAN system as the correlation value passes the constant threshold value. The applied autocorrelation structure of the algorithm can be implemented simply compared to conventional packet detection algorithms. The proposed frequency offset estimation architecture is designed for phase rotation process structure, internal bit reduction to reduce hardware size and the frequency offset adjustment block to reduce look-up table size unlike the conventional structure. If the received signal can be compensated by estimated frequency offset through the correction block, it can reduce the impact on the frequency offset. Through the performance result, the proposed structure has lower hardware complexity and gate count compared to the conventional structure. Thus, the proposed structure for OFDM-based WPAN systems can be applied to the initial synchronization process and high-speed low-power WPAN chips.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.175-182
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• 2013

This paper proposes a readability enhancement filter for Patterned Retarder (PR) display. In general, when some texts in stereoscopic images are shown on PR display, their readability tends to be lowered. In order to overcome this problem, we present a readability enhancement algorithm which consists of readability filtering stage and post-processing stage for specific characters. First, each input stereo image is divided into an odd line image and an even line image. Then, they are independently up-scaled vertically by using Lanczos filter. Next, two up-scaled line images are averaged considering vertical phase difference. In post-processing stage, two specific characters which are normally difficult to read on PR display are detected, and they are filtered for additional readability enhancement. Here, this additional filtering is based on a specific brightness adjustment, and is applied only for two characters. The experiment results show that the proposed method achieves significant improvement in terms of readability in comparison with the previous scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.869-872
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• 2005

This paper presents a new switchable dual mode VCO(Voltage-Controlled Oscillator). The VCO is efficient in dual mode operation and has self-bias adjustment based on the operation frequencies of 2.4 GHz and 5 GHz. The switching is done using MOS transistors and tuning is done using MOS varactors. It is implemented using TSMC 0.18${\mu}$m CMOS technology. It is powered by 1.8V supply. The measured results showed that the overall tuning range is approximately 13% at 5 GHz and 8% at 2.4 GHz. The measured phase noise is approximately -102 dBc/Hz at 1 MHz offset for 5 GHz and -89 dBc/Hz at 600kHz offset for 2.4 GHz. The VCO showed tail currents of 2mA in 5GHz mode and 2.5mA in 2.4GHz mode from a 1.8 V supply, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1309-1316
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• 2016

This paper suggests adjusting TCP for smartphones that often have small size data transmission tendency. Usage of smartphones has been risen dramatically in recent years, including frequent usage of real-time map search, public transportation search, online games, and SNS. Because the small size data transmission ends before the phase of the TCP congestion avoidance, this paper suggests an algorithm that increases the transmission speed ahead of the traffic congestion event. The algorithm reduces unnecessary delay by data size-driven adjustment of the Linux Quick ACK and Nagle's algorithm. Therefore, TCP is improved to maintain a high transmission rate steadily in small data transmission.