• Geomechanics and Engineering
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• 제9권5호
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• pp.601-618
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• 2015

Soil-reinforcement interaction mechanism is an important issue in the design of geosynthetic reinforced soil structures. This mechanism depends on the soil properties, reinforcement characteristics and interaction between these two elements (soil and reinforcement). In this work the shear strength of sand/geotextile interfaces were characterized through direct and simple shear tests. The direct shear tests were performed on a conventional direct shear device and on a large scale direct shear apparatus. Unreinforced sand and one layer reinforced sand specimens were characterized trough simple shear tests. The interfaces shear strength achieved with the large scale direct shear device were slightly larger than those obtained with the conventional direct shear apparatus. Notwithstanding the differences between the shear strength characterization through simple shear and direct shear tests, it was concluded that the shear strength of one layer reinforced sand is similar to the sand/geotextile interface direct shear strength.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.

• 한국초등과학교육학회지:초등과학교육
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• 제33권2호
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• pp.335-351
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• 2014

The 96 elementary school teachers' the degrees of understandings about the characteristics of the currents according to the connection methods of batteries in simple electric circuits were investigated. In this study, the concepts on the characteristics of currents according to the connection methods of batteries were divided 'the learned concepts' and 'the differentiated concepts'. The characteristics of the currents in the region of the larger resistance of load than the internal resistance of a battery were called the learned concepts, they are taught in the science curriculum. While the characteristics of the currents in the region of the smaller resistance of load than the internal resistance of a battery were called the differentiated concepts, they are not exposed clearly in the science curriculum. The results obtained in this study are as follows: The average score related to the learned concepts was relatively high, while the degree of the teachers' cognitions of the internal resistance of a battery and the resistance of wires were low. Also the average score related to the differentiated concepts was very low because it seems so new to the elementary school teachers. It strongly suggests that the elementary school teachers did not understand meaningfully the characteristics of the currents related to the connections of batteries on the ground of the cognitions of the internal resistances of batteries and the resistances of loads in simple electric circuits. Hence, they might experience difficulties due to the problems occurred in relation to the connections of batteries in the elementary school science lessons.

• 디지털산업정보학회논문지
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• 제10권4호
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• pp.151-160
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• 2014

In this paper, a comparison of superpixel characteristics based on SLIC(simple linear iterative clustering) for several color feature spaces is presented. Computer vision applications have come to rely increasingly on superpixels in recent years. Superpixel algorithms group pixels into perceptually meaningful atomic regions, which can be used to replace the rigid structure of the pixel grid. A superpixel is consist of pixels with similar features such as luminance, color, textures etc. Thus superpixels are more efficient than pixels in case of large scale image processing. Generally superpixel characteristics are described by uniformity, boundary precision and recall, compactness. However previous methods only generate superpixels a special color space but lack researches on superpixel characteristics. Therefore we present superpixel characteristics based on SLIC as known popular. In this paper, Lab, Luv, LCH, HSV, YIQ and RGB color feature spaces are used. Uniformity, compactness, boundary precision and recall are measured for comparing characteristics of superpixel. For computer simulation, Berkeley image database(BSD300) is used and Lab color space is superior to the others by the experimental results.

• 대한핵의학회지
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• 제2권1호
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• pp.1-7
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• 1968

Presented here are the results for clinical study on 65 cases of simple goiter the author treated during the period of 4 years and 10 months from Jan. 1963 through Oct. 1967 at the Seoul National University Hospital and Han-Il Hospital. It had been customary to classify simple goiter, according to the gross morphological characteristics of the thyroid gland, as diffuse and nodular type. This paper attempts to investigate the histopathological changes and treatment of simple goiter respectively. Sixty five cases of simple goiter were classified into 4 types; namely degenerative type was 20 cases (30.8%), proliferative type was 7 cases (10..8%), colloidal type was 24 cases (36.9%) and cyst formation with degeneration was 14 cases (21.5%), on the basis of histopathological findings. Thus, it is essential that simple goiter should be differentiated from thyroid tumors as soon as practicable. The effectiveness of medical treatment with desicated thyroid and autohemotherapy for certain simple goiter are also discussed.

• 대한원격탐사학회지
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• 제37권5_3호
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• pp.1475-1490
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• 2021

SAR 이미지의 통계적 특징을 이용하여 유류오염영역을 특정하는 방법은 분류규칙이 복잡하고 이상값에 의한 영향을 많이 받는다는 한계가 있어, 최근 인공신경망을 기반으로 유류오염영역을 특정하는 연구가 활발히 이루어지고 있다. 하지만, 다양한 유류오염 사례에 대해 모델의 탐지 성능 및 특성을 평가한 연구는 부족하였다. 따라서, 본 연구에서는 기본적인 구조의 CNN인 Simple CNN과 픽셀 단위의 영상 분할이 가능한 U-net을 이용하여, CNN의 구조와, 유류오염의 분포특성에 따른 모델의 탐지성능차이가 존재하는지 분석하였다. 연구결과, 축소경로만 존재하는Simple CNN과 축소경로와 확장경로가 모두 존재하는U-net의 F1 score는 86.24%와 91.44%로 나타나, 두 모델 모두 비교적 높은 탐지 정확도를 보여주었지만, U-net의 탐지성능이 더 높은 것으로 나타났다. 또한 다양한 유류오염 사례에 따른 모델의 성능 비교를 위해, 유류오염의 공간적 분포특성(유류오염 주변의 육지의 분포)과 선명도(유출된 기름과 해수의 경계면이 뚜렷한 정도)를 기준으로, 유류오염 발생사례를 4가지 유형으로 구분하여 탐지 정확도를 평가하였다. Simple CNN은 각각의 유형에 대해 F1 score가 85.71%, 87.43%, 86.50%, 85.86% 로 유형별 최대 편차가 1.71%인 것으로 나타났으며, U-net은 동일한 지표에 대해 89.77%, 92.27%, 92.59%, 92.66%의 F1 score를 보여 최대 편차가 2.90% 로 두 CNN모델 모두 유류오염 분포특성에 따른 수치상 탐지성능의 차이는 크지 않은 것으로 나타났다. 하지만 모든 유류오염 유형에서 Simple CNN은 오염영역을 과대탐지 하는 경향을, U-net은 과소탐지 하는 경향을 보여, 모델의 구조와 유류오염의 유형에 따라 서로 다른 탐지 특성을 가진다는 것을 확인하였고, 이러한 특성은 유류오염과 해수의 경계면이 뚜렷하지 않은 경우 더 두드러지게 나타났다.

• 복식
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• 제64권7호
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• pp.156-171
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• 2014

This study attempted to comprehend the usage of the modular system in fields through literature review and objective research, as well as analysis of its expression characteristics in fashion. It tried to provide inspiring visual data for the fashion design of the modular system. After analyzing architecture and product-related books, Internet data and advanced research, the four expression characteristics of the modular system were obtained. Firstly, the formative expression characteristics of the modular system in fashion were simplicity, extensibility, variability and diversity. Secondly, of the formative expression characteristics expressed in modern fashion, simplicity (30%) was the highest, followed by extensibility (27%), diversity (22%) and variability (21%). Thirdly, simple silhouette and structure were used to express simplicity, usually simple geometric figures. In contrast, extensibility was expressed through the expansion and exaggeration of the area, length and volume of the clothes. In terms of variability, the typical characteristics of modules were reflected. For diversity, heterogeneous materials were used, and informality was expressed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.253-260
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• 2004

Many scholars and researchers has been studied for many kinds of soil characteristics, but a lot of part are still unsolved. Cyclic load-induced decreasing characteristics of strength and stiffness of soils are also well not known among them. To know that, the characteristics of five kinds of soils; clay, plastic and non-plastic silt, sand, and a weathered soil are compared with dividing two types as plastic or non-plastic soils through direct simple shear(DSS) test. From the results of DSS test, it is known that decreasing characteristics of strength and stiffness are different according to soil types. The strength of plastic and non-plastic soils increases with increment of plasticity index and decrement of volume decrease potential, respectively. And the decreasing stiffness of plastic and non-plastic soils increases with decrement of plasticity index and increment of volume decrease potential, respectively.

• 대한기계학회논문집A
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• 제22권4호
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• pp.879-886
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• 1998

It is very important to understand the vibration and noise characteristics of a structure to developed quiet machines and lessen their noise. In this paper, the vibration and sound radiation characteristics of a simple and a bar-stiffened plate have been investigated using numerical and experimental techniques. In numerical process, FEM analysis has been performed for the vibration level ; the time-space squared and averaged velocity and BEM analysis for sound radiation parameters ; sound power and radiation efficiency. In experimental process, FFT signal processing method has been used. While a power from an exiciter is applied to the structure by using a point contact, sound intensity and vibration level has been measured. Based on these two data, the radiation efficiency has been calculated. Results show that the radiation efficiency for the stiffened structure increases compared to the simple plate, due to the extra edges provided by the stiffener.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.465-470
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• 1998

A cross-flow fan often generates discrete noise call blade passing frequency tones. Several methods have been investigated to reduce this BPF noise, where the random distribution of blades is the most promising one. A simple and effective algorithm to determine a random distribution of blades is proposed which considers fan. performance as well as noise characteristics. The proposed method is verified by a simple numerical model and is applied in manufacturing cross-flow fan samples. Also some experiments are carried out and the experimental results are analyzed.