• The KIPS Transactions:PartB
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• v.9B no.5
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• pp.673-680
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• 2002

This paper proposes a method for detecting edge using an evolutionary programming and a momentum back-propagation algorithm. The evolutionary programming does not perform crossover operation as to consider reduction of capability of algorithm and calculation cost, but uses selection operator and mutation operator. The momentum back-propagation algorithm uses assistant to weight of learning step when weight is changed at learning step. Because learning rate o is settled as less in last back-propagation algorithm the momentum back-propagation algorithm discard the problem that learning is slow as relative reduction because change rate of weight at each learning step. The method using EP-MBP is batter than GA-BP method in both learning time and detection rate and showed the decreasing learning time and effective edge detection, in consequence.

• Geomechanics and Engineering
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• v.14 no.2
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• pp.195-202
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• 2018

Many laboratory experiments on crack propagation under uniaxial loading and biaxial loading have been conducted in the past using transparent materials such as resin, polymethyl methacrylate (PMMA), etc. However, propagation behaviors of three-dimensional (3D) cracks in rock or rock-like materials under tri-axial loading are often considerably different. In this study, a series of true tri-axial loading tests on the rock-like material with two semi-ellipse pre-existing cracks were performed in laboratory to investigate the acoustic emission (AE) characteristics and propagation characteristics of 3D crack groups influenced by intermediate principal stress. Compared with previous experiments under uniaxial loading and biaxial loading, the tests under true tri-axial loading showed that shear cracks, anti-wing cracks and secondary cracks were the main failure mechanisms, and the initiation and propagation of tensile cracks were limited. Shear cracks propagated in the direction parallel to pre-existing crack plane. With the increase of intermediate principal stress, the critical stress of crack initiation increased gradually, and secondary shear cracks may no longer coalesce in the rock bridge. Crack aperture decreased with the increase of intermediate principal stress, and the failure is dominated by shear fracturing. There are two stages of fracture development: stable propagation stage and unstable failure stage. The AE events occurred in a zone parallel to pre-existing crack plane, and the AE zone increased gradually with the increase of intermediate principal stress, eventually forming obvious shear rupture planes. This shows that shear cracks initiated and propagated in the pre-existing crack direction, forming a shear rupture plane inside the specimens. The paths of fracturing inside the specimens were observed using the Computerized Tomography (CT) scanning and reconstruction.

• Geomechanics and Engineering
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• v.17 no.1
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• pp.57-67
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• 2019

Water-induced strength reduction is one of the most critical causes for rock deformation and failure. Understanding the effects of water on the strength, toughness and deformability of rocks are of a great importance in rock fracture mechanics and design of structures in rock. However, only a few studies have been conducted to understand the effects of water on fracture properties such as fracture toughness, crack propagation velocity, consumed energy, and microstructural damage. Thus, in this study, we focused on the understanding of how microscale damages induced by water saturation affect mesoscale mechanical and fracture properties compared with oven dried specimens along three notch orientations-divider, arrester, and short transverse. The mechanical properties of calcite-cemented sandstone were examined using standard uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) tests. In addition, fracture properties such as fracture toughness, consumed energy and crack propagation velocity were examined with cracked chevron notched Brazilian disk (CCNBD) tests. Digital Image Correlation (DIC), a non-contact optical measurement technique, was used for both strain and crack propagation velocity measurements along the bedding plane orientations. Finally, environmental scanning electron microscope (ESEM) was employed to investigate the microstructural damages produced in calcite-cemented sandstone specimens before and after CCNBD tests. As results, both mechanical and fracture properties reduced significantly when specimens were saturated. The effects of water on fracture properties (fracture toughness and consumed energy) were predominant in divider specimens when compared with arrester and short transverse specimens. Whereas crack propagation velocity was faster in short transverse and slower in arrester, and intermediate in divider specimens. Based on ESEM data, water in the calcite-cemented sandstone induced microstructural damages (microcracks and voids) and increased the strength disparity between cement/matrix and rock forming mineral grains, which in turn reduced the crack propagation resistance of the rock, leading to lower both consumed energy and fracture toughness ($K_{IC}$).

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.135-144
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• 2022

Electromagnetic topology (EMT) technique is a method to analyze each component of the electromagnetic propagation environment and combine them in the form of a network in order to effectively model the complex propagation environment. In a typical commercial communication channel model, since the propagation environment is complex and difficult to predict, a probabilistic propagation channel model that utilizes an average solution, although with low accuracy, is used. However, modeling techniques using EMT technique are considered for application of propagation and coupling analysis of threat electromagnetic waves such as electromagnetic pulses, radio wave models used in electronic warfare, local communication channel models used in 5G and 6G communications that require relatively high accuracy electromagnetic wave propagation characteristics. This paper describes the effective implementation method, algorithm, and program implementation of the electromagnetic topology (EMT) method analyzed in the frequency domain. Also, a method of deriving a response in the time domain to an arbitrary applied signal source with respect to the EMT analysis result in the frequency domain will be discussed.

• BMB Reports
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• v.56 no.12
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• pp.657-662
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• 2023

Neurodegenerative diseases are characterized by distinct protein aggregates, such as those of α-synuclein and tau. Lysosomal defect is a key contributor to the accumulation and propagation of aberrant protein aggregates in these diseases. The discoveries of common proteinopathies in multiple forms of lysosomal storage diseases (LSDs) and the identification of some LSD genes as susceptible genes for those proteinopathies suggest causative links between LSDs and the proteinopathies. The present study hypothesized that defects in lysosomal genes will differentially affect the propagation of α-synuclein and tau proteins, thereby determining the progression of a specific proteinopathy. We established an imaging-based high-contents screening (HCS) system in Caenorhabditis elegans (C. elegans) model, by which the propagation of α-synuclein or tau is measured by fluorescence intensity. Using this system, we performed RNA interference (RNAi) screening to induce a wide range of lysosomal malfunction through knock down of 79 LSD genes, and to obtain the candidate genes with significant change in protein propagation. While some LSD genes commonly affected both α-synuclein and tau propagation, our study identified the distinct sets of LSD genes that differentially regulate the propagation of either α-synuclein or tau. The specificity and efficacy of these LSD genes were retained in the disease-related phenotypes, such as pharyngeal pumping behavior and life span. This study suggests that distinct lysosomal genes differentially regulate the propagation of α-synuclein and tau, and offer a steppingstone to understanding disease specificity.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.03a
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• pp.265-272
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• 1998

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.364-369
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• 2012

This paper presents an experimental study on the radio propagation characteristics in subway tunnel at 18GHz frequency band which has been assigned to video transmission between train and wayside. The radio propagation tests are carried out in the subway tunnel of Seoul Metro using the antenna and communication devices of the prototype video transmission system. The measurement results show that 18GHz radio propagation in subway tunnel has smaller path loss than that of general outdoor radio environment. It is also cleared that the arch-type tunnels have smaller radio propagation losses than rectangular tunnels, and single track tunnels have smaller pass loss than double track tunnels. From the measurements, the radio propagation coverage is worked out as 520 meters. The curved tunnels which cannot have LOS communication between transmitter and receiver have large pass losses and fluctuation profile along distance. The radio propagation coverage along curved tunnels is worked out as 300 meters. These investigation results can be used to design the 18GHz radio transmission system for subway tunnel by providing the optimized wayside transmitter locations and handover algorithm customized to the radio propagation characteristics in subway tunnels.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.326-336
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• 2020

This study was conducted to investigate productivity of strawberry plants as affected by propagation method and cultivation system. Transplants propagated by cutting propagation and pinning propagation were planted and grown for a whole production period in soil and hydroponic cultivation systems. Growth parameters, fruit productivity, and fruit quality were measured during the whole harvest period. The results showed that propagation method and cultivation system had significant effects on vegetative growth of strawberry plants. Total fruit yield per plant and average fruit weight per fruit during the whole harvest period were significantly lower in the plants grown in soil cultivation system. Total unmarketable fruit ratio was significantly greater in soil cultivation system than that in hydroponic cultivation system. Small fruits were the primary unmarketable fruits in soil cultivation system, while malformed fruits were the primary unmarketable fruits in hydroponic cultivation system. The overall high quality of fruit was found in February, and the plants cultivated in hydroponic cultivation system had higher quality of fruit as compared with that in soil cultivation system. It is concluded that cutting propagation is better than pinning propagation, and hydroponic cultivation system is better than soil cultivation system for fruit productivity of strawberry.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.40-40
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• 2019

는쟁이냉이는 전국 각지 산지의 응달이나 물가에서 자생하는 여러해살이풀이다. 3월 경 눈을 뚫고나와 가장 이른 봄나물로 식용하기도 한다. 특유의 매운 맛이 있어 식용작물로 발전가능성이 높은 식물종이다. 따라서 본 연구는 는쟁이냉이 재배기술 정립을 위한 기초자료 수집의 일환으로 수행되었다. 차광에 따른 는쟁이냉이 생육특성을 비교 분석하기 위해 경북 봉화군 소재 국립백두대간수목원 양묘장 노지에 무차광, 40% 차광, 55%차광, 65%차광 처리구를 배치 후, 실험을 진행하였다. 생육특성의 비교를 위해 초장, 초폭, 엽 수, 엽길이, 엽너비, 엽병길이, SPAD 값 총 7가지 항목에 대해 생장기(6월), 휴면기(9월) 두 차례 측정하였다. 측정 결과, 모든 측정값이 차광구가 무차광구보다 높게 나타났다. 또한 무차광구는 6월 조사 이후, 7월 말까지 생장량이 줄어들다가 전량 지상부 고사가 발생하여 는쟁이냉이 재배를 위해서는 차광처리가 필수적으로 필요하다는 것을 확인할 수 있었다. 측정항목 중 초장, 초폭, 엽길이, 엽너비, 엽병길이는 차광율이 높을수록 증가하는 경향을 보였다. 그러나 엽록소함량을 추정할 수 있는 SPAD 값은 40% 차광구가 가장 높았고 55%차광구, 65%차광구에서는 오히려 감소하는 경향을 보였다. 또한 엽 수도 40% 차광구가 가장 높았다. 위 결과를 종합해볼 때, 는쟁이냉이 재배 시 55% 이상의 차광율을 적용하면 잎 자체의 크기 증대를 기대할 수 있으며, 40% 수준의 차광율을 적용하면 잎 수와 혁질의 잎을 생산할 수 있을 것으로 여겨진다. 다만, 본 실험은 는쟁이냉이 재배 생산량에 대한 부분에 집중하였고 상품화를 위해서는 품질에 관한 연구가 추가적으로 이루어져야 할 것으로 판단된다.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.14-14
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• 2019

참삿갓사초는 전국에 분포하는 여러해살이풀로 사료용, 사방용 소재로 사용되며 조경용, 관상용 지피식물로 사용되기도 한다. 참삿갓사초의 대량증식을 위해 가장 효과적인 파종 시기를 추정하기 위해 생장상을 이용해 인공적인 온도조건을 주고 참삿갓사초 종자의 발아율을 조사하였다. 실험을 위해 온도를 항온조건(30, 25, 20, 15, $5^{\circ}C$)과 변온조건(15/30, 20/10, $25/15^{\circ}C$) 총 8가지 조건으로 설정하여 발아율을 매일 측정하였다. 광조건은 명/암을 매일 12시간씩 반복하였다. 항온조건에서 발아율은 $20^{\circ}C$가 $17{\pm}7%$로 가장 우수하였고, $25^{\circ}C$ ($12{\pm}2.8%$), $30^{\circ}C$ ($3{\pm}1.9%$) 순으로 나타났으며, $15^{\circ}C$, $5^{\circ}C$에서는 발아하지 않았다. 그러나 $20^{\circ}C$와 $25^{\circ}C$조건에서 통계적인 유의차는 발생되지 않았다. 한편, 변온조건에서의 발아율은 $15/30^{\circ}C$가 $91{\pm}3.8%$로 가장 우수하였고, $25/15^{\circ}C$ ($89{\pm}4.1%$), $20/10^{\circ}C$ ($69{\pm}3.4%$) 순으로 나타났다. 그러나 $15/30^{\circ}C$와 $25/15^{\circ}C$조건에서 통계적인 유의차는 발생되지 않았다. 따라서 참삿갓사초의 종자발아를 위해서는 변온이 필요하며, $25^{\circ}C$ 이상의 온도가 필요하다. 이러한 결과를 바탕으로 가장 효과적인 파종 시기를 추정할 때, 낮-밤 $10^{\circ}C$ 이상의 기온차가 있는 초여름~늦여름 사이가 가장 적절할 것으로 판단된다.