• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2103-2107
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• 2009

우리나라는 계절별 강수량 변화가 크기 때문에 하천개발 및 관리에 어려움이 많을 뿐만 아니라 하천에 설치된 많은 취수보와 같은 하천횡단구조물로 인해서 하천 생태계가 악화되어 있다. 최근 들어 하천생태 복원을 위하여 자연형 하천 조성사업과 보에 어도설치가 활발하게 이루어지고 있다. 그러나 어류 소상에 효과적인 어도를 설치하기 위해서는 하천에 서식하는 다양한 어류에 대한 어류역학적인 특성이 필요하나 이에 대한 조사연구는 미흡한 실정이다. 특히 어류의 유영력이나 도약력은 어도의 설계의 완성도 및 어도시설 운영관리에서 대단히 중요한 요소이다. 따라서 본 연구에서는 우리나라 하천에 널리 서식하는 어류인 피라미를 대상으로 도약능력에 관하여 실험하였다. 어류의 도약능력은 낙차가 있는 흐름에서 어류가 상류로 이동하기 위한 중요한 이동수단이다. 어류의 도약에 영향을 미치는 어도 인자로는 격벽높이, 월류수심, 유속, 어도경사 및 유량을 들 수 있다. 피라미의 도약능력 실험은 폭 28cm, 길이 140cm인 개수로에서 격벽높이는 5${\sim}$10cm, 월류수심 1.2${\sim}$5cm, 낙차 약 4cm의 조건으로 이루어졌다. 실험유량은 약 0.378${\ell}$/s이고, 경사는 1:20${\sim}$1:15 이다. 도약능력은 소상율의 크기로 판단하였으며 피라미의 소상율은 격벽높이 10cm와 월류수심 3cm에서 유속 4.19cm/sec일 때를 정점으로 유속의 증가에 따라 급격히 감소하였다. 이는 어류의 생태적인 특성과 작은 유속이 어류이동 유인효과에 영향이 작기 때문인 것으로 판단된다. 또한 피라미의 체장이 클수록 소상율도 증가하는 관계를 나타내었다.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.155-161
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• 2018

For the efficient recovering of collapsed sloped soil, using a soil binder that can support the soil strongly and help the growth of plants is very important. The soil binder should also have functions of recovering the soil ecologically as well as be environmental friendly materials. In this research, optimum values of the water content and permeability and direct shear strength were searched by adding the water absorbent and coagulant into the soil binder. The polyacrylamide (PAM) with various anionic strength, super absorbent polymer (SAP) and cellulose ether (CE) were used as a soil binder, water absorbent and coagulant, respectively. Effects of the soil binder on the characteristics of soil were observed by changing the mixing ratio of PAM, SAP and CE. Experimental results showed that the soil binder increased the direct shear strength tens of times and the water content around two times, whereas decreased the water permeability. Also, the addition of CE to increase the coagulation of SAP increased more of the direct shear strength and water content.

• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.37-44
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• 2000

In this paper, we described the real-time implementation effort of MPEG-4 audio HVXC (Harmonic Vector eXcitation Coding) algorithm for very low bitrates, which has target applications from mobile communications to Internet telephony, on current high performance floating point TMS320C6701 DSP. We adopted a hardware structure for real-time operation. In order for software optimization, we used C- and assembly-language level optimizations for time-critical functional codes. Utilizing the internal program memory of the DSP as the program cache, the internal data memory overlap technique and DMA functionality, we could get a goal of realtime operation of HVXC codec both at 2 kbit/s and at 4 kbit/s. For an encoder at 2 kbit/s, the optimization ratio to original code is about 96 %. Finally, we got the subjective quality of MOS 2.45 at 2 kbit/s from an informal quality test.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.127-133
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• 1999

The conventional fractal image compression based on discrete wavelet transform uses the fixed block size in fractal coding and reduces PSNR at low bit rate. This paper proposes a fractal image coding based on discrete wavelet transform which improves PSNR by using variable block size in fractal coding. In the proposed method. the absolute values of discrete wavelet transform coefficients are computed. and the discrete wavelet transform coefficients of different highpass subbands corresponding to the same spatial block are assembled. and the fractal code for the range block of each range block level is assigned. and then a decision tree C. the set of choices among fractal coding. "0" encoding. and scalar quantization is generated and a set of scalar quantizers q is chosen. And then the wavelet coefficients. fractal codes. and the choice items in the decision tree are entropy coded by using an adaptive arithmetic coder. This proposed method improved PSNR at low bit rate and could achieve a blockless reconstructed image. As the results of experiment. the proposed method obtained better PSNR and higher compression ratio than the conventional fractal coding method and wavelet transform coding.rm coding.

• Korean Journal of Environment and Ecology
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• v.24 no.1
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• pp.37-45
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• 2010

This study was conducted to provide a database for biotope conservation and restoration of the Jeonju region in North Cheolla Province. To accomplish this task, investigations were made on the characteristics of the distribution pattern of naturalized plants in the region. From May to June 2008, the flora and lists of naturalized plants were investigated and, based on these data the ratio of naturalization was calculated. The results of this investigation areas follows: a total of 113 families and 54 species were found in the flora. The naturalized plants among them amounted to 19 families and 54 species. The ratio of naturalization was most high in the biotope type of rural dried stream(36.4%). The biotype that showed the lowest ratio of naturalization was coniferous natural forest type, which had no naturalized plants in it. The average naturalization ration of the Jeonju region turned out to be 18.9%, which is similar to that of other mid-size cities in Korea.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4C
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• pp.312-320
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• 2008

The macroblock-based adaptive interpolation filter method has been considered to be able to achieve high coding efficiency in H.264/AVC. In this method, although the filter selection criterion considered in terms of rate and distortion have showed a good performance, it still leaves room for improvement. To improve high coding efficiency better than conventional method, we propose a new filter selection criterion which considers two bit rates, motion vector and prediction error, and reconstruction error. In addition, the algorithm for reducing the overhead of transmitting the selected filter information is presented. Experimental results show that the proposed method significantly improves the coding efficiency compared to ones using conventional criterion. It leads to about a 5.19% (1 reference frame) and 5.14% (5 reference frames) bit rate savings on average compared to H.264/AVC, respectively.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.195-198
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• 2012

The N basis functions are typically chosen so that Surface reflectance functions(SRFs) and spectral power distributions (SPDs) can be accurately reconstructed from their N-dimensional vector codes. Typical rendering applications assume that the resulting mapping is an isomorphism where vector operations of addition, scalar multiplication, component-wise multiplication on the N-vectors can be used to model physical operations such as superposition of lights, light-surface interactions and inter-reflection. The vector operations do not mirror the physical. However, if the choice of basis functions is restricted to characteristic functions then the resulting map between SPDs/SRFs and N-vectors is anisomorphism that preserves the physical operations needed in rendering. This paper will show how to select optimal characteristic function bases of any dimension N (number of basis functions) and also evaluate how accurately a large set of Munsell color chips can approximated as basis functions of dimension N.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.5
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• pp.59-76
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• 2009

This study was conducted to supply basic data for restoration and management of forests in Civilian Control Zone, with surveying naturalized plants around abandoned military camps. The total study sites are 72 abandoned military camps, from Gosung in east region to Paju in west region of Civilian Control Zone. The naturalized index of total area is 12.6%, and naturalized index of east and middle regions are 12.1% and 8.4%. But its index of west region is 15.9%. These results are due to geographical characteristics. The east and middle regions are in steep mountainous districts, and so but west region is flat district, and so naturalized plants was imported by only army. But west region is in flat districts, and so imported method of naturalized plants is very various. The main naturalized plants are Ambrosia trifida and Ambrosia artemisiifolia var. elatior in Civilian Control Zone. The main dispersion pattern of naturalized plants are gravity dispersion pattern ($D_4$) and wind and water dispersion pattern ($D_1$). The all naturalized plants are photophilic plants in survey sites. And so, if abandoned military camps are recovered to forests, the naturalized plants are disappeared because of the change of sunlight condition. So it is necessary to manage and recover forests, even if that area is Civilian Control Zone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.2
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• pp.199-208
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• 2014

Code division multiple access (CDMA) is one of the promising medium access control (MAC) schemes for underwater acoustic sensor networks because of its robustness against frequency-selective fading and high frequency-reuse efficiency. As a way of performance evaluation, sea or lake experiment has been employed along with computer simulation.. In this study, we design the underwater CDMA forward-link transceiver and evaluate the feasibility aginst harsh underwater acoustic channel in water-tank first. Then, based on the water-tank experiment results, we improved the transceiver and showed the improvements in a lake experiment. A pseudo random noise code acquisition process is added for phase error correction before decoding the user data by means of a Walsh code in the receiver. Interleaving and convolutional channel coding scheme are also used for performance improvement. Experimental results show that the multiplexed data is recovered by means of demultiplexing at receivers with error-free in case of two users while with less than 15% bit error rate in case of three and four users.

• Journal of IKEEE
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• v.22 no.1
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• pp.68-73
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• 2018

In this paper, we propose an efficient algorithm for mapping a $360^{\circ}$ circular image to a planar image. The proposed algorithm consists of obtaining size of the planar image, calculating the distance between the camera and the planar image, calculating horizontal angle of camera and planar image, calculating vertical angle between camera and planar image, calculating the position of a pixel that matches pixels in a $360^{\circ}$ circular image to pixels in a planar image. Experiments were performed to evaluate the efficient algorithm for mapping the proposed $360^{\circ}$ circular image to the plane image. The reconstruction rate of the mapped plane image was confirmed 99% and the image quality of the mapped plane image was confirmed 72%. Since the results were higher than the standard values of commercial software, the effectiveness of the algorithm was confirmed.