• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.5
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• pp.444-450
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• 2012

The evaluation of a zonal RANS-LES approach is documented for the prediction of broadband noise generated by the flow past unmodified and serrated airfoil trailing edges at a high Reynolds number. A multi-domain decomposition is considered, where the acoustic sources are resolved with a LES sub-domain embedded in the RANS domain. A stochastic vortex method is used to generate synthetic turbulent perturbations at the RANS-LES interface. The simulations are performed with a general-purpose unstructured control-volume code FLUENT. The far-field noise is calculated using the aeroacoustic analogy of Ffowcs Williams-Hawkings. The results of the simulation are validated through the full-scaled wind turbine acoustic measurements. It is found that the present approach is adequate for predicting noise radiation of serrated trailing edge flow for low noise rotor system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.145-151
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• 2012

In this study, finite element analysis is carried out to estimate horizontal forces needed for the required power calculation and vertical forces applied on the structural analysis model for the development of automatic serrated surface at metal gasket core machining system. By considering of elasto-plastic material characteristics, nonlinear contact analysis was conducted to compute these loads according to the change of roll reduction, frictional coefficient and core thickness. As the result, horizontal and vertical reaction force variations are found according to parameters and maximum reaction force is also confirmed to be most affected by roll reduction.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.7 s.361
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• pp.31-36
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• 2007

A saw-tooth waveform generator whose frequency can be controlled with a do bias current is proposed. The generator utilizes operational transconductance amplifiers (OTA's) as switching element. It features simple and wide sweep capability The circuit built with commercially avaliable components exhibits good linearity of current-to-frequency transfer characteristics and relatively low temperature sensitivity.

• Animal Systematics, Evolution and Diversity
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• v.12 no.2
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• pp.101-105
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• 1996

A new genus and species belonging to the family Aphodiidae (Coleoptera) Koreoxyomus koreanus gen. et sp. nov., is described from Korea. And a genus known from Japan, Mozartius is discussed because it is almost same taxa with present new genus but its original description is not stable taxonomically.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.466-466
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• 2010

유도결합형플라즈마(ICP)에서 부유 랑뮤어 탐침에 정현파, 톱니파, 사각파, 삼각파 형태의 전압 파형들을 쉬스에 인가하였을 때, 탐침으로 들어오는 고조파전류들의 특성을 넓은 범위에서 연구 하였다. 탐침으로 들어오는 플라즈마전류파형 및 기생전류파형의 모양과 고조파전류들에 대해 고찰하였고, 각각의 전압파형을 인가하였을 때 다양한 압력과 파워조건에서 부유 랑뮤어 탐침법을 이용하여 전자온도와 플라즈마 밀도를 측정하고, 측정결과는 싱글 랑뮤어 탐침법과 비교하였다. 정현파, 삼각파는 싱글 랑뮤어 탐침법과 잘 일치하는 결과를 보였고, 톱니파는 실험상의 오차로 정확한 측정이 안 되었으며, 사각파는 전류파형의 과도현상으로 인해 측정이 안되었다. 그 외에 기존의 부유 랑뮤어 탐침법과 다르게 부유전위의 변화와 제 1 고조파들의 비를 이용해서 전자온도를 구하는 방법도 소개한다.

• Korean journal of applied entomology
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• v.63 no.1
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• pp.67-72
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• 2024

In this study, two mesostigmatic mites, Holostaspella crenulata Krantz, 1967 (Machrochelidae) and Lasioseius floridensis Berlese, 1916 (Blattisociidae) are recognized in Korea for the first time. The diagnoses, distributional data, drawing plates, and microscopic photographs are provided for each species.

• Life and Agrochemicals
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• s.247
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• pp.50-51
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• 2009

북아메리카가 원산지인 일년생잡초로 외래잡초의 하나이다. 잎 가장자리에 톱니 유무가 미국외풀과 밭뚝외풀의 차이점이다. 벼 생육초기에 피해가 현저히 나타나며 방제 소홀시 44%까지 벼 수량이 감소된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.381-390
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• 2016

In this study, aeroacoustic characteristics of combined fan are investigated and noise was reduced by applying Serrated Trailing Edge which is known as the method to reduce fan noises. Unsteady CFD (Computational Fluid Dynamics) analysis was carried out using Lattice Boltzmann Method(LBM) to figure out the combined fan's aeroacoustics and experimental results was used to verify simulation results. Results show that different BPFs are generated at the each inner fan and outer fan on the different frequency while Blade Passing Frequency(BPF) of general fans is constant on the entire frequency range. Boundary vortex and vortex shedding are suppressed or dispersed by applying the Serrated Trailing Edge to the inner fan. Furthermore, broadband noise and fan's torque are reduced.

• Korean Journal of Plant Taxonomy
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• v.39 no.2
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• pp.114-119
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• 2009

Two naturalized species, Euphorbia dentata Michx. and Securigera varia (L.) Lassen were newly reported from Korea. Euphorbia dentata, "Top-Ni-Dae-Geuk", was found from Jungbu Highway, Daechang-ri, Daechang-myeon, Yeongcheon-si, Gyeongsangbuk-do. It is distinguished from E. pulcherrima by its life form, which is herbaceous, and its upper leaves, which are uniformly green. Securigera varia, "Wang-Gwan-Gal-Kwi-Na-Mul", was found from Hangang, Yeouido, Seoul. The genus Securigera is unrecorded in Korea and distinguished from genus Hedysarum by rose-colored flowers, a peduncle 5-10 cm and by having dense umbels at the tips of the peduncles.

• Journal of Industrial Convergence
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• v.21 no.4
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• pp.123-131
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• 2023

The purpose of this study was to investigate difference of activity of scapular stabilizer muscles among push-up, knee push-up and wall push-up exercise. Eight male college students were recruited as participants without any history of shoulder or pathology. The results showed that serratus anterior, anterior deltoid, infraspinatus were higher muscle activities than other scapular stabilizer muscles during push-up exercise and muscle activity of standard push-up exercise was higher muscle activity than that of Knee and Wall push-up exercise. Also, We know that knee push-down exercise was more effective than wall push-down exercise for scapular stabilization.