• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.617-624
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• 2021

The accurate estimation of the number of signals included in the received signal is required for the AOA(: Angle-of-Arrival) estimation, the interference suppression, the signal reception, etc. AIC(: Akaike Information Criterion) and MDL(: Minimum Description Length) algorithms, which are known as the typical algorithms to estimate the signal number, estimate the number of signals according to the minimum of each criterion. As the number of antenna elements increased, the estimation performance is enhanced, but the computational complexity is increased because values of criteria for entire antenna elements should be calculated for finding their minimum. In order to improve this problem, in this paper, we propose AIC and MDL algorithms based on the beamspace, which efficiently estimate the number of signals while reducing the computational complexity by reducing the dimension of an array antenna through the beamspace processing. In addition, we provide computer simulation results based on various scenarios for evaluating and analysing the estimation performance of the proposed algorithms.

• Land and Housing Review
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• v.13 no.3
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• pp.107-113
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• 2022

With increasing airtight building construction aimed at reducing energy consumption, indoor relative humidity is increasing which can lead to condensation and moisture damage in multi-family residential buildings. This has led to increased implementation of mechanical ventilation to control indoor moisture. However mechanical ventilation systems consume additional energy and generate noise. As this leads to occupant discomfort, it is necessary to select a ventilation system that addresses the energy and noise issues. This research measured the ventilation performance, energy consumption, and noise level of mechanical ventilation devices in multi-family residential buildings. TOPSIS, a multi-criteria decision making technique was used to determine appropriate ventilation strategies in addition to occupant ventilation system operation preference.

• The Mathematical Education
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• v.62 no.3
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• pp.417-433
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• 2023

In the 2022 revised mathematics curriculum, a new content on 'Movement of a point' was added. Therefore, this study analyzed the contents of the movement of a point presented in Finnish mathematics textbooks as elements of spatial orientation. Analysis was conducted by dividing it into direction, distance, and route. As a result of the study, in Finnish textbooks, directions were expressed in various ways, such as linguistic, visual, and coded expressions. In the case of distance, activities to move as much as the distance or compare the distance were presented using the number of cells, length, steps, coordinate points, ratio, etc. In the case of routes, activities such as moving according to instructions, making routes, finding the route, and modifying the route were presented using unconditional movement and conditional movement. In particular, the movement of a point could be linked not only to various mathematical content areas such as 'number and arithmetic' and 'change and relationship', but also to digital literacy and programming education. Knowing that the movement of a point can be presented in various ways according to the direction, distance, and route, it is expected that it can be used to organize the contents of the 2022 revised mathematics textbook.

• Journal of Wetlands Research
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• v.15 no.2
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• pp.251-264
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• 2013

There are some factors affecting the shorebirds in selecting a coastal inland roost site where they have to stay during the high tide when the entire intertidal zone is covered with water. We investigated eight species (Eastern Curlews Numenius madagascariensis, Green Shanks Tringa nebularia, Bar-tailed Godwits Limosa lapponica, Grey Plovers Pluvialis squatarola, Dunlins Calidris alpine, Whimbrels Numenius phaeopus, Eurasian Curlews Numenius arquata and Terek Sandpipers Xenus cinereus) to identify the spatial and temporal variability in coastal inland roost use in the area and the factors influencing the use. We considered the area and length of the standing water in the roost site, temperature, wind speed, the time of migration and the intensity of disturbance. As a result, number of individuals and type of species using the roost site varied across spatial and temporal scales. And the factors affecting the roost use was species-specific. The roost site of the study area was a closed shrimp farm however, it has been converted to a Salicornia herbacea, a salt marsh plant, farm recently. In a situation where coastal inland roost site is needed, we hereby describe a resolution for the juxtaposition of shorebirds and farming.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.2
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• pp.30-35
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• 1996

It is well known that the improved methods of the estimation of the service power margin is necessary to design a optimum ship and to operate economically a ship. Unfortunately, most conventional methods of the predicting of the service power margin are not so accurate that attention should be payed to improve this. From this overview, it is importance with. the effects of waves, as recommended by the 15th and 16th International Towing Tank Conference in 1978 and l981. However the progress of research in this field is very slow mainly since it is taken so long time to take data about hull roughness according to ship ages. For instance, it would be taken 17 or 25 years to measure ideally the data for a ship. Moreover it would be also necessary to take data for many types of ships to lead a general solution. A relationship between roughness and ship age are studied in this paper considering full scale data. A comparison is also made between the effects of hull roughness and of weather at sea for the ship.

• Journal of Acupuncture Research
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• v.19 no.6
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• pp.97-110
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• 2002

목적 : 본 연구는 (a) 저빈도 전침의 만성 단발성 관절염에 대한 치료 효과와 (b) 척수에서 동통과 관련되는 지표인 P 물질과 trk A mRNA의 발현조절에 미치는 영향을 연구하기 위해 실행되었다. 방법 : Complete Freund's adjuvant를 실험동물의 우측 경족근관절에 주입하여 관절염을 유발시키고 9주 동안 관찰하였다. 만성 관절염의 최적의 치료조건을 찾기 위하여 각각 세 종류의 경혈(환도, 용천, 족삼리)과 전침자극강도(0.5, 1, 2 mA)를 사용하여, 행동학적 지표로서 동통을 측정하였다. 측정 결과 가장 큰 효과를 나타낸 군을 선택하여 RT-PCR 방법을 사용하여 P 물질 및 trk A mRNA의 변화를 척수 후각과 후근신경절에서 측정하였다. 결과 : 관절의 굴신을 통한 통증 검사와 족과관절 둘레 길이 측정을 통하여 관찰한 결과 원위부에 위치한 환도에 저강도의 자극을 시행한 경우(환도, 0.5 mA)가 가장 우수한 치료 효과를 나타내었다. RT-PCR을 시행한 결과, 환측 후근신경절의 P물질이 관절염 유발 대조군의 경우 정상군에 비해 증가하였고 환도-0.5mA 군에서 다시 감소하는 것을 관찰하였으며, trk A는 관절염 유발군의 경우 척수 후각에서 양측성 증가를 나타내었고 이는 전침치료에 의해 다시 감소되는 것을 관찰하였다. 결론 : 환도 0.5mA의 저빈도 전침은 관절염을 효과적으로 감소시킬 뿐 아니라 관절염으로 증가된 후근신경절의 P 물질과 척수후각의 trk A mRNA 발현을 효과적으로 감소시켰으며, 이는 원위취혈로 선혈된 환도혈의 만성관절염에 대한 치료효과를 분명히 보여준다고 할 수 있다.

• Korean journal of communication and information
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• v.45
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• pp.7-48
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• 2009

The recent crises of Marxism do not mean Marx’s crisis. Marx said that he was not a Marxist. The purposes of this essay explore (1) the modern identity of the political economy; (2) the possibilities of mutual understanding between neoclassical economics and Marxist economics; (3) problems of the political economy in media and communication industry. I have begged for analytical Marxists, because of their good fruits. They accepted the methods of modern social science and they constituted a tremendous advance in the application of the scientific methods to the study of society. In insisting on micro-foundations(methodological individualism), analytical Marxism distinguished itself from structuralism and functionalism. I appreciate that analytical Marxism has reduced a theory to practice. But the works didn’t listen to everyone(from Marxists to un-Marxists), and explain everything. Making theory with production/consumption, macro/micro, and structure/behavior is a road to the political economy in the long run. It also applies to media and communication industry. The realm of media/communication is broad, which in philosophy, humanities, politics, economics, sociology, and engineering. And media policy is more complicated by politicians who look at the same situation from different angles. By the aid of interdisciplinary research, the political economy of media/communication shall explain at full length.

• Journal of Internet Computing and Services
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• v.15 no.6
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• pp.125-132
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• 2014

Since frequent pattern mining was proposed in order to search for hidden, useful pattern information from large-scale databases, various types of mining approaches and applications have been researched. Especially, frequent graph pattern mining was suggested to effectively deal with recent data that have been complicated continually, and a variety of efficient graph mining algorithms have been studied. Graph patterns obtained from graph databases have their own importance and characteristics different from one another according to the elements composing them and their lengths. However, traditional frequent graph pattern mining approaches have the limitations that do not consider such problems. That is, the existing methods consider only one minimum support threshold regardless of the lengths of graph patterns extracted from their mining operations and do not use any of the patterns' weight factors; therefore, a large number of actually useless graph patterns may be generated. Small graph patterns with a few vertices and edges tend to be interesting when their weighted supports are relatively high, while large ones with many elements can be useful even if their weighted supports are relatively low. For this reason, we propose a weight-based frequent graph pattern mining algorithm considering length-decreasing support constraints. Comprehensive experimental results provided in this paper show that the proposed method guarantees more outstanding performance compared to a state-of-the-art graph mining algorithm in terms of pattern generation, runtime, and memory usage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.565-568
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• 2003

2세대 초전도 선재로 알려져 있는 $YBa_2Cu_3O_{7-\delta}$ coated conductor는 금속모재/완충층/초전도층/보호층의 구조를 가진다. 2개 이상의 산화물 다층 박막으로 이루어진 완충층은 금속기판의 집합조직을 초전도층까지 전달하는 역할, 금속기판의 금속이 초전도층으로 확산되어 초전도층의 전기적 특성을 열화시키는 것을 막아주는 확산장벽으로의 역할 등을 수행한다. 1차 완충층은 금속기판의 집합조직을 유지하여야하며, 금속기판의 산화를 방지하면서 증착 되어야 한다. coated conductor 제조를 위한 첫 단계로 Pulsed Laser Deposition법을 이용하여 cube texture된 Ni 기판 위에 $Y_2O_3$ 박막을 증착 하였다. 최적의 증착 조건을 찾기 위해 증착 챔버의 산소 및 $H_2/Ar$ 혼합가스 분압과 기판온도를 변화시키면서 증착 하였다. $Y_2O_3$층의 (100) 집합조직은 기판온도 $600{\sim}700^{\circ}C$와 산소 분압 $0.01{\sim}0.1mTorr$에서 증착된 Y2O3 박막에서 금속기판과 유사한 집합조직을 얻을 수 있었다. 최적의 증착 조건에서 $Y_2O_3$ (222) ${\Phi}-scan$의 full width at half maximum (fwhm)이 $11^{\circ}$이고 (400) ${\omega}-scan$ fwhm은 $6^{\circ}$이었다.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.61-66
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• 1979

This experiment was conducted to find out the simple and economical method to improve physical properties of the soil that was very poor for the establishment of orchard. Jeonnam clay loam soils distributed mainly on rolling and hill side slope, were treated with the explosion of two kinds of dynamite at the depth of 1 m. The change of physical properties was investigated vertically and horizontally after soil profile had settled to some extent. The results were summarized as : 1. The original soil was very high in bulk density and soil hardness. Total porosity and aeration porosities were lower than critical level providing root elongation. It was more apparent in the subsoil than in the surface soil. 2. It was recognized that soil mass destruction and cracking by dynamite explosion decreased soil bulk density and soil hardness and increased porosity, especially non-capillary pores. 3. Effective radius of the improved physical properties by explosion with two dynamites was 100cm at 60cm depth and 30cm at 80cm depth. But with the use of three dynamites it was 100cm at 80cm depth. 4. It was thought that soil mass destruction and cracking caused by explosion was uneven in the two dynamites, and three dynamites was more effective to improve physical properties evenly. 5. With the use of two dynamites, Ammonium explosive was superior to gelatin dynamite.