• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.5
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• pp.640-647
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• 2007

This paper presents a joint controller for a humanoid robot based on genetic algorithm. h humanoid robot has basically instability during walking because it isn't fixed on the ground. Moreover nonlinearities of the joints increase its instability. If one of them isn't satisfied, the robot may fall down at the ground during walking. To attack one of those problems, joint controller is proposed. It can perform tracking control preciously and reduce the effect of nonlinearities by gear, limitation of the input voltage, coulomb friction and so on. This controller is based on fuzzy-sliding mode controller (FSMC) and compensator and control gains are searched by a proposed genetic algorithm. It can reduce the effect by nonlinearities. Also, to improve the tracking performance, the proposed controller has motion controller. From the given controller, a humanoid robot can moved more preciously. Here, all the processes are investigated through simulations and it is verified experimentally in a real joint system for a humanoid robot.

• Composites Research
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• v.19 no.5
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• pp.12-19
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• 2006

In this paper, conceptual structural design of the main wing for a small scale WIG(Wing in Ground Effect) among high speed ship projects, which will be a high speed maritime transportation system for the next generation in Rep. of Korea, was performed. The Carbon/Epoxy material was selected for the major structure, and the skin-spar with a foam sandwich structural type was adopted for improvement of lightness and structural stability. As a design procedure for the present study, firstly the design load was estimated through the critical flight load case study, and then flanges of the front and rear spars from major bending loads and the skin and the spar webs from shear loads were preliminarily sized using the netting rule and the rule of mixture. Stress analysis was performed by a commercial FEA code, NASTRAN. From the stress analysis results for the first designed wing structure, it was confirmed that the upper skin between the front spar and the rear spar was unstable fer the buckling. Therefore in order to solve this problem, a middle spar and the foam sandwich type structure at the skin and the web were added. After design modification, the structural safety and stability for the final design feature was confirmed. In addition to this, the insert bolt type structure with eight high strength bolts to fix the wing structure to the fuselage was adopted for easy assembly and removal as well as in consideration of more than 20 years fatigue life.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.86-86
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• 2017

마늘파종기는 파종기구동부와 파종후 파종홀의 복토역할을 하는 파종기롤러, 지면과의 마찰을 통해 바퀴의 회전토크가 발생하며 발생된 토크는 파종기 내부 동력으로 전달되어 전체 파종시스템(배종, 호퍼캠, 파종부)을 동작 시키는 기능을 수행하는 파종바퀴, 마늘종구를 한알씩 집어올려 중간이송컵으로 이송하는 자세교정컵이 포함된 배종부와 자세교정컵에서 낙하된 마늘종구를 땅속으로 파종하는 파종장치로 구성된다. 배종율 95%, 2립 배종률 5% 성능을 확보할 수 있는 기술이 개발될 경우 세계적으로도 독보적인 기술 우위를 확보할 수 있다. 이와 같은 기본적인 기능을 구현할 수 있는 컨셉모델에 대한 설계를 수행하여 시제품개발 전 기구해석과 구조해석 등을 위한 기본설계를 수행하였다. 배종율 95% 이상을 확보하기 위해서는 기존의 현장경험의 의한 설계 방식으로는 한계가 있기 때문에 시뮬레이션 및 분석 개발이 필요한데, 프레임은 고정밀 마늘종구 배종부 장착을 위한 기본 구조물로써 작동시 동력을 얻기 위한 바퀴와 연계가 되도록 설계되었으며, 호퍼는 배종 수행을 위해 마늘을 저장해 두는 통으로써 배종부와 연결된다. 배종부의 배종판이 회전함에 따라서 배종판의 홈이 호퍼 내로 들어갔다 나오면서 마늘을 집게되며, 동력 전달부는 배종판을 회전시켜주고, 회전 속도 조절을 가능하게 한다. 파종부는 배종부에서 중간컵을 통해 하나씩 공급해준 마늘을 땅에 심는 부분으로서. 프레임의 바퀴 회전과 연동되어 회전하고 설계하였다. 배종판에서 중간컵으로 이송된 마늘을 파종부의 파종컵에 받아 회전하면서 땅속에 파종컵이 묻히면 파종컵이 열리면서 땅속에 마늘을 심는 원리이다. 조간조정은 7조식의 경우 초기설치시 고정되도록 설계되었으며 농촌진흥청 기계화 표준재배안에 따라 의성마늘 기준 $14{\times}14cm$(조간${\times}$주간)를 기준으로 개발하였다. 조간조정은 기계가 설치되면 조정하기 어려우므로 14cm로 설계하였으며, 주간조정은 원형배종장치의 구동기어부의 속도비로 간격을 조정할 수 있도록 기어장치를 설계하였다. 주간조정은 13에서 18cm의 범위에서 작동하도록 설계되었으며, 필요에 따라 간격조절이 가능함. 마늘은 그 크기가 다르고, 형상도 다르기 때문에 종자에 따른 개별적인 파종기술들이 개발되어야하기 때문에 개발 기간이 오래 걸리고, 수익에 비하여 개발비가 과다하게 요구되는 실정인데 축적된 시뮬레이션 툴을 이용한 파종기 분석 기술을 확보할 경우 다른 파종기의 연구 개발에도 크게 도움이 될 것으로 기대되며, 생육측정 실험과 동역학 해석 툴 RecurDyn을 통해 파종기의 기구학적 분석을 통한 설계반영 인자를 도출할 계획이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.153-153
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• 2010

p-i-n 형 비정질 실리콘 박막 태양전지에서 p층은 창물질(window material)로서 전기 전도도가 크고, 빛 흡수가 적어야한다. p층의 두께가 얇으면 p층 전체가 depletion layer가 되고 충분한 diffusion potential을 얻을 수 없어 open-circuit voltage ($V_{oc}$)가 작아진다. 반대로 p층 두께가 두꺼워지면 빛 흡수가 증가하고, 표면 재결합이 문제가 되어 변환효율이 감소한다. 밴드갭이 큰 물질로 창층을 제작하게 되면 보다 짧은 파장의 입사광이 직접 i층을 비추므로 Short-circuit current ($I_{sc}$) 와 fill factor를 증가시킬 수 있다. 하여 본 연구에서는 기존의 창층으로 사용되는 Boron을 doping한 p-type a-Si:H 대신에 $N_2O$를 첨가한 p-type a-$SiO_x$:H의 $N_2O$ flow rate에 따른 밴드갭의 변화에 관한 연구를 수행하였다. p-type a-$SiO_x$:H Layer는 $SiH_4$, $H_2$, $N_2O$, $B_2H_6$ 가스를 혼합하여 증착하게 되는데 $SiH_4$, 가스와 $H_2$ 가스의 혼합비는 1:20, $B_2H_6$ 농도는 0.5%로 고정 하였으며 $N_2O$의 flow rate을 가변하며 증착하였다. $N_2O$의 가변조건은 5에서 50sccm으로 가변하여 증착하며 일반적으로 사용되는 RF-PECVD (13.56MHz)를 이용하였고 증착 온도는 175도, 전극간의 거리는 40mm, 파워와 압력은 30W, 700mTorr로 고정하여 진행하였다. 전기적 특성을 알아보기 위해 eagle 2000 Glass를 사용하였고 구조적 특성은 p-type wafer를 사용하여 각각 대략 200nm의 두께로 증착하였다. 증착 두께는 Ellipsometry를 이용하였으며 전기 전도도는 Agilent사의 4156c를 구조적특성은 FT-IR을 사용하여 측정하였다. Conductivity(${\sigma}_d$)는 $N_2O$가 증가함에 따라 $8.73\;{\times}\;10^{-6}$에서 $5.06\;{\times}\;10^{-7}$으로 감소하였고 optical bandgap ($E_{opt}$)은 1.71eV에서 2.0eV로 증가함을 알 수 있었다. 또한 reflective index(n)의 경우는 4.32에서 3.52로 감소함을 나타내었다. 기존의 p-type a-Si:H에 비해 상당한 $E_{opt}$을 가지므로 빛 흡수에 의한 손실을 줄임으로서 $V_oc$를 향상 시킬 수 있으며 동시에 짧은 파장에서의 입사광이 직접 i층을 비추므로 $I_{sc}$와 FF를 향상 시킬 수 있으리라 예상된다. 다소 낮은 전도도만 개선한다면 고효율의 박막 태양전지를 제작 할 수 있을 것으로 기대된다.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.217-226
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• 2020

Ajaeng is the bowed string instrument among zither instruments in East Asia, which has a circular form to date, and it has established itself as an important instrument in today's creative Gugak along with traditional music. Looking at previous prior studies, musical instrument studies have not been actively conducted due to insufficient data from musical history studies, and this study looked at the origin, form of musical instrument, and performance methods of zither bowed string instrument through historical records of Chinese Yazheng and music drawings. The analysis of various documents showed that Ajaeng originated from an ancient Chinese traditional musical instrument called Chuk. In terms of the performance style, the Chinese Yazheng had different musical forms depending on the purpose and location of the performance, and there was a method of standing up and fixing the musical instrument horizontally to the ground. Ajaeng in Korea has been handed down without much change in the form of musical instruments introduced in China during the Goryeo Dynasty and the way they sit on the floor and play on a pedestal. Through this study, we hope that it will help to preserve and develop traditional music and Korean traditional musical instruments by enhancing understanding of musical.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.555-562
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• 2021

Recently, in the field of geospatial information construction, unmanned aerial vehicles have been increasingly used because they enable rapid data acquisition and utilization. In this study, photogrammetry was performed using fixed-wing, rotary-wing, and VTOL (Vertical Take-Off and Landing) unmanned aerial vehicles, and geospatial information was constructed using two types of unmanned aerial vehicle LiDAR (Light Detection And Ranging) sensors. In addition, the accuracy was evaluated to present the utility of spatial information constructed through unmanned aerial photogrammetry and LiDAR. As a result of the accuracy evaluation, the orthographic image constructed through unmanned aerial photogrammetry showed accuracy within 2 cm. Considering that the GSD (Ground Sample Distance) of the constructed orthographic image is about 2 cm, the accuracy of the unmanned aerial photogrammetry results is judged to be within the GSD. The spatial information constructed through the unmanned aerial vehicle LiDAR showed accuracy within 6 cm in the height direction, and data on the ground was obtained in the vegetation area. DEM (Digital Elevation Model) using LiDAR data will be able to be used in various ways, such as construction work, urban planning, disaster prevention, and topographic analysis.

• Journal of Korean Society of Forest Science
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• v.78 no.1
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• pp.30-34
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• 1989

Effects on noise attenuation of the hedge species, Thuja orientalis L. and Euonymus japonicus Thunb., widely used as road side hedges, were analysed at the frequencies of 1,000, 2,000 and 3,150 Hz., respectively. The present experiments were carried out both in the field and in a Semianechoic Chamber. As increasing the distances from the noise source, attenuation rates of noise level were increased at high frequencies. But the attenuation rates of the noise level at low frequencies showed varied as the distances increased, and this trend appeared to be caused by the influence of ground waves. Generally, in this experiment, Thuja orientalis L., which is a coniferous species, showed more effective on the abilities of noise attenuation than that of Euonymus japonicus Thunb., which is a broad-leaved evergreen species.

• Korean Journal of Cognitive Science
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• v.27 no.2
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• pp.325-353
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• 2016

The visual span refers to the number of letters that can be accurately recognized without moving one's eyes. The size of the visual span is affected by sensory factors such as perimetric complexity, crowding, and mislocation of letters. Korean Hangul utilizes rather unique alphabetic-syllabary writing system, quite different from English and Chinese writing systems. Due to this combinatorial nature of the script, the visual span for Hangul characters can also be affected by the letter type (e.g., CV vs CVCC). The present study examined the effect of syllable complexity on the visual span for Hangul by comparing letter recognition accuracy across four letter type conditions (C only, CV, CVC, and CVCC). We also aimed to determine the meaningful letter type(s) that is associated with differences in reading abilities in Korean. Using a trigram presentation method, we found that overall recognition accuracy declined as syllable complexity increased. However, the visual span for CVC type was greater than that for CV type, suggesting that the effect is not necessarily linear, and that there might be other factors affecting the visual span for these types of letters. C and CV type showed fairly strong positive correlations with reading comprehension, suggesting that these might be the meaningful units for measuring visual span in relating to reading abilities.

• The Journal of the Korea Contents Association
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• v.15 no.1
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• pp.64-73
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• 2015

Describing the filmography of Yong-ho KIM simply in a few sentences is considered nearly impossible. For the last 20 years and longer, KIM has been building up his career energetically as he never lets himself obsessed with any particular boundaries or areas but work on everything from paper advertisements to art galleries, advertising photographs and pure photographs. The Photolanguage personally mentioned by Yong-ho KIM himself is to visualize this imaginary story in a form of photograph, which one would come up with before shooting. When it comes to the advertising photographs, since they are used basically to sell products, they are considered rather temporary, and in addition, they photograph the products mostly under these bright lights with colorful backgrounds behind. However, Yong-ho KIM was recognized for presenting very much different work as he went even beyond these old stereotypes of the advertising photographs. The advertising photographs processed by KIM do more than merely introducing details or functions of some products, but they deliver these values and cultures that consumers can enjoy and gain through these original stories about the products. Of several pieces of KIM's work, this advertisement on Hyundai Card named was invited to an exhibition by a private gallery after the work was exposed through various media. The work was even purchased, and that was something that had not happened before in the history of the relevant field. When a photograph is purchased, it makes the photograph recognized for its value to be possessed, and when a photograph is displayed, it, again, makes the photograph win recognition as an art work. This thesis discusses the Photolanguage found in the works of Yong-ho KIM, one of the most well-known advertising photographers in South Korea. The research inquiries that have been analyzed in the body of the thesis, therefore, are the photographs and language in the digital era, the story-telling advertisements and these works by Yong-ho KIM.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.2
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• pp.15-22
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• 2012

The variation in the wind speed with height above ground is called the wind shear profile. In the field of wind resource assessment, analysts typically use one of two mathematical relations to characterize the measured wind shear profile: the logarithmic profile (log law) and the power law profile (power law). The logarithmic law uses the surface roughness as a parameter, and the power law uses the power law exponent as a parameter. The shape of the wind shear profile typically depends on several factors, most notably the roughness of the surrounding terrain and the stability of the atmosphere. Since the atmospheric stability changes with season, time of day, and meteorological conditions, the surface roughness and the power law exponent also tends to change in time. For this study, Using the observed data from Met-mast, located in Pyeongdae, Handong in Jeju. we used the matlab and windograper to calculate roughness length and the law exponents. These calculations are similar to reference the data, but they have different ranges. In the ocean case, each reference data and calculated data was the same, but the crop area is higher than the earlier studies. In addition, the agricultural village is lower than the earlier studies.