• Journal of the Korean GEO-environmental Society
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• v.21 no.6
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• pp.19-25
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• 2020

In the recent downtown works, there are frequent cases where the work on existing piles is impossible due to the influence from lack of space and surrounding environment. In such cases, there has been growing cases of using the micropile method that is available to work with the small equipment and asserts the bearing capacity of the existing piles. The micropile method is a type of drilled shaft with the diameter of a pile to be around 75 mm~300 mm that, even for a case where it has certain surrounding structure, foundation and spatial obstacle, there is almost no work difficulty and the work is feasible under all types of soil conditions. In addition, the work can be done in places where the ceiling of the building is low with less vibration and noise in the work process that such method is significantly used for foundation reinforcement of existing buildings. With respect to the motion characteristics that are changed depending on the foundational characteristics or when the micropile is applied with compression or tensile force, there is very few studies conducted. Therefore, under this study, through the data analysis of the field loading test regarding the micropile worked in the fields, it clarifies the settlement and characteristics of bearing capacity following the embedded condition of the ingredients and piles that consist the foundation if the compression and tensile force are applied to the micropile, and by facilitating the statistical analysis program, SAS, to carry out the analysis on the main elements influencing on settlement of the micropile and bearing capacity.

• Strategy21
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• s.41
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• pp.261-293
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• 2017

Nuclear power is a way of attaining an enormous amount of energy with relatively small amount of resources and after it has been introduced to the submarine since 1954, there are approximately 150 of nuclear powered submarine currently on a mission around the world. This is due to the maneuverability, mountability and covertness of nuclear submarines. However, there are other tasks, not only the high level of nuclear technology that are needed to be dealt with in order to construct nuclear powered submarine. The biggest task of all is to secure the enriched uranium. Accordingly, this research is about the way of enriching and securing the nuclear fuel that are used in the nuclear submarine with the characteristics, merits and demerits of the nuclear submarine. Due to the fact that the pressurized water reactor in South Korea is the reactor that was originally built for the development of nuclear powered submarine, many parts is designed to be suitable for the submarine propulsion. However, in order to apply this to submarine it is needed to consider additional requests such as the position of reactor, accident-coping system, radioactive covering, reactor output adjustment and ship's pitch and roll in order to apply this to submarine. Nuclear submarines have much higher speed based on the powerful propulsion in comparison with diesel-electric submarine and also have bigger loading area. Besides, there is no need to snorkel and they also have advantages in covertness with the multi-noise proof system. The nuclear technology in South Korea has seen the dramatic development since 1962 and in 1998 reached to the level that we have succeeded in the localization of nuclear plant and exported the world-class one-piece small-sized reactor (SMART) to UAE. To operate these reactors, we import the whole quantity of low-enriched uranium and having our own uranium enrich facility is not probable because of the budget and international regulations. With the ROK/US nuclear agreement revised on 2015 November, the enrichment of uranium that are available without special permission has changed up to 20%. According to the assumption that we use the 20% enrichment of Uranium on U.S. virginia class submarine, it is necessary to change the fuel after 11 years and it will cause additional cost of 1 billion dollars. But the replace period by the uranium's enrichment rate is not fixed so that it is possible to change according to the design of reactor. Therefore, I would like to make a suggestion on two types of design concepts of nuclear submarine that can be operated for 30 years without nuclear fuel change by using the 20% enriched uranium from ONNp.First of all, it is possible by increasing the size of reactor by 3 times and it results in the 1,000t increase of the weight. And secondly, it is by designing the one piece reactor to insert devices such as steam turbine, condenser into the inside of nuclear core like the Rubis class submarines of France.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.53-63
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• 2009

This work proposes a 10b 100MS/s 27.2mW $0.8mm^2$ 0.18um CMOS ADC for WLAN such as an IEEE 802.11n standard. The proposed ADC employs a three-stage pipeline architecture and minimizes power consumption and chip area by sharing as many circuits as possible. Two multiplying DACs share a single amplifier without MOS switches connected in series while the shared amplifier does not show a conventional memory effect. All three flash ADCs use only one resistor ladder while the second and third flash ADCs share all pre-amps to further reduce power consumption and chip area. The interpolation circuit employed in the flash ADCs halves the required number of pre-amps and an input-output isolated dynamic latch reduces the increased kickback noise caused by the pre-amp sharing. The prototype ADC implemented in a 0.18um n-well 1P6M CMOS process shows the DNL and INL within 0.83LSB and 1.52LSB at 10b, respectively. The ADC measures an SNDR of 52.1dB and an SFDR of 67.6dB at a sampling rate of 100MS/s. The ADC with an active die area of $0.8mm^2$ consumes 27.2mW at 1.8V and 100MS/s.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.59-65
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• 2008

In this paper, a new adaptive resource allocation scheme is proposed in orthogonal frequency-division multiple access(OFDMA) systems with rate proportionality constraints. The problem of maximizing the overall system capacity with constraints on bit error rate, total transmission power and rate-proportionality for user requiring different classes of service is formulated. Since the optimal solution to the constrained fairness problem is extremely complex to obtain, a low-complexity suboptimal algorithm that separates subchannel allocation and power allocation is proposed. Firstly, the number of subchannels to be assigned to each user is determined based on the users' average signal-to-noise ratio and rate-proportion. Subchannels are subsequently distributed according to the modified max-min criterion. Lastly, based on the subchannel allocation, the optimal power allocation by solving the Language dual problem is proposed. Additionally, in order to reduce the computational complexity, iterative rate proportionality tracking algorithm is proposed for maximizing the capacity together with maintaining the rate proportionality constraint.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.102-112
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• 2013

In this paper, two step processing method of contour extraction and complement which contain hexagonal shape for low contrast and noisy images is proposed. This method is based on the combination of Laplacian-Gaussian filter and an idea of filters which are dependent on the shape. At the first step, an algorithm which has six masks as its extractors to extract the hexagonal edges especially in the corners is used. Here, two tricorn filters are used to detect the tricorn joints of hexagons and other four masks are used to enhance the line segments of hexagonal edges. As a natural image, a corneal endothelial cell image which usually has regular hexagonal form is selected. The edge extraction of hexagonal shapes in corneal endothelial cell is important for clinical diagnosis. The proposed algorithm and other conventional methods are applied to noisy hexagonal images to evaluate each efficiency. As a result, this proposed algorithm shows a robustness against noises and better detection ability in the aspects of the output signal to noise ratio, the edge coincidence ratio and the extraction accuracy factor as compared with other conventional methods. At the second step, the lacking part of the thinned image by an energy minimum algorithm is complemented, and then the area and distribution of cells which give necessary information for medical diagnosis are computed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.682-690
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• 2012

In this paper, a highly linear self oscillating mixers(SOM) using second harmonic injections are presented. The H-slot defected ground structure(DGS) is designed as a balanced resonator for oscillation in the proposed SOM. Since the H-slot DGS resonator achieves a high Q factor, it is a suitable structure to provide low phase noise for the oscillator. The single balanced mixer is utilized in this work and it provides good LO-RF isolation since balanced LO signals are suppressed at the RF input port. In order to inject the second harmonic of the IF, we propose two different methods using feedback loops. In the first method, IF achieves a 3.08 dB conversion gain at 226 MHz with input power of -20 dBm at 5 GHz RF input signal. The IF achieves 2 dB conversion gain at 423 MHz with the input power of -20 dBm at 5.2 GHz RF input signal in the second method. The measured IMD3s are 61.8 dB and 65 dB for the each method. These SOMs present improved linearity compared to that without the second harmonic injection because IMD3s are improved by 18. dB and 21 dB for each method.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.23-31
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• 2011

The simple bacteria cooperative optimization (sBCO) algorithm that we developed as one of optimization algorithms has shown relatively good performances, but their performances were limited by step-by-step movement of individuals at a time. In order to solve this problem, we proposed a new method that assigned a speed to each individual according to its rank and it was confirmed that it improved the performances of sBCO in some degree. In addition to the assigning of speed to the individuals, we employed a new mutation operation that most existing evolutionary algorithms used in order to enhance the performances of sBCO in this paper. A specific percent of bad individuals are mutated within an area that is proportion to the rank of the individual in the mutation operation. That is, Gaussian noise of large standard deviation is added as the fitness of individuals is low. From this, the probability that the individuals with lower ranks can be located far from its parent will be increased. This causes that the probability of falling into local optimum areas is decreased and the probability of fast escaping the local optimum areas is increased. From experimental results with four function optimization problems, we showed that the performances of sBCO with mutation operation and individual speed were increased. If the optimization function is quite complex, however, the performances are not always better. We should devise a new method for solving this problem as a further work.

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.187-196
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• 2016

This study was performed to improve the foaming generated in the effluent of wastewater treatment plant from March 2015 to July 2016. The main cause of foaming was air entrainment by an impinging jet and the internal accumulation by the diffusion barrier. Particularly, the foam growth was most active when there is low tide and larger discharge. To solve this problem, we experimented after installing fine mesh screen and the artificial channel device with underwater discharging outlet in the treated wastewater discharge channel and the outlet, respectively. As a result, the effects of foam reduction by devices ranged 85.0~92.0% and 70.7~85.6%, respectively. In addition, the foam and the noise were easily solved, first of all look to contribute to the prevention of complaints. Our device studies were applied to a single wastewater treatment plant. However, it is considered to be able to apply in other similar cases of domestic sewage treatment plants.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.8-15
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• 2010

As environmental friendly energy system, distributed micro gasturbine is focused on new energy source for overcoming brand new construction area of power generation. This distributed micro gasturbine system has the powerful characteristics as belows; 1) environmental friendly features NOx < 9 ppm, noise < 65 db 2) various fuel flexbility which is used such as natural gas, diesel, low calory new & renewable fuel, kerosene. 3) high specific output power based on small area and is avilable for very easy and compact installation. There are many new installation sites in USA and Japan from 1998. On the other hand the exhisting large power system was constructued by the sea side, this compact power system is now installed by enduser in downtown area and supplying combined heat & power, has the various apllication on-site power generation. In recently, there is the very important issue for new & reliablbe energy development and spreading out. This paper represent as belows for important system characteristics; 1) grid connection modeling 2) system operation characteristics 3) on-site operation result and evaluation output of power quality analysis.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.445-448
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• 2015

Recently there has been increasing interest in the filter to reduce the proportion of low-energy photons in the polychromatic X-ray, affect the quality of the image quality by X-ray hardening effect is a situation that has been overlooked. In this study, by evaluating the change in FSR based on the filter and it was quantitatively discuss scatter dose affecting the medical image quality. The results of the experiment, as the thickness of the filter is increased, up to 13.9%p, that tends to FSR increases appearance were evaluated. Based on these results, in compliance with the thickness of the filter that has been recommended in KS standard, even while reducing the radiation dose of the patient, in addition to the noise to about 1%p within the FSR only medical image the contribution to it is conceivable. Therefore, even while reducing radiation dose of the patient, in order to improve the quality of the medical image, the use of appropriate filter is considered important.