• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.180-185
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• 2023

To improve the efficiency of water electrolysis, it is essential to develop an oxygen evolution reaction (OER) electrocatalyst with high performance and long-term stability, accelerating the reaction rate of OER. In this study, a hollow metal-organic framework (MOF)-derived ruthenium-cobalt oxide catalyst was developed to synthesize an efficient OER electrocatalyst. As the synthesized catalyst increases the surface exposure of ruthenium, a low overpotential (386 mV) was observed at a current density of 10 mA/cm² with a low Tafel slope. It is expected to be able to replace noble metal catalysts by showing higher mass activity and stability than commercial RuO₂ catalysts.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.3
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• pp.137-142
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• 2022

Every year, the number of wild animals appearing in human settlements increases, resulting in increased damage to property and human life. In particular, the damage is more severe when wild animals appear on highways or farmhouses. To solve this problem, ecological pathways and guide fences are being installed on highways. In addition, in order to solve the problem in farms, horn repelling using sensors, installing a net, and repelling by smell of excrement are being used. However, these methods are expensive and their effectiveness is not high. In this paper, we used YOLO (You Only Look Once), an AI-based image analysis method, to analyze harmful animals in real time to reduce malfunctions, and high-brightness LEDs and ultrasonic frequency speakers were used as extermination devices. The speaker outputs an audible frequency that only animals can hear, increasing the efficiency to only exterminate wild animals. The proposed system is designed using a general-purpose board so that it can be installed economically, and the detection performance is higher than that of the devices using the existing sensor.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.325-335
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• 1996

Visual features are crucial for monitoring the growth state, indexing the drying performance, and grading the quality of oak mushrooms. A computer vision system with neural net information processing technique was utilized to quantize quality factors of a dried oak mushrooms distributed over the cap and gill sides. In this paper, visual feature extraction algorithm were integrated with the neural net processing to deal with various fuzzy patterns of mushroom shapes and to compensate the fault sensitiveness of the crisp criteria and heuristic rules derived from the image processing results. The proposed algorithm improved the segmentation of the skin features of each side, the identification of cap and gill surfaces, the identification of stipe states and removal of the stipe, etc. And the visual characteristics of dried oak mushrooms were analyzed and primary visual features essential to tile quality evaluation were extracted and quantized. In this study, black and white gray images were captured and used for the algorithm development.

• Composites Research
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• v.21 no.5
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• pp.1-8
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• 2008

In recent years, the reversed L-shaped perforated shear connector has been developed to mitigate the problem associated with headed stud and Perforbond shear connector and to simulate the simultaneous failure of concrete and shear connector. And FRP perforated shear connector has been applied to composite concrete and FRP module in the FRP-concrete composite bridge deck. The design criterion of the reversed L-shaped and FRP perforated shear connector has not been established yet since the lack of experimental and analytical study results. In this paper, the existing design equations for the Perforated were briefly discussed and the equation fur the prediction of shear resisting capacity of the reversed L-shaped and FRP perforated shear connector was suggested based on the experimental test, FEM analysis. and the existing equation for the Perfobond. The predict results obtained by the suggested equation arc compared with the experimental results, the applicability and effectiveness of suggested equation was verified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1786-1793
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• 2022

Cyber-attacks such as smishing and hacking mail exploiting COVID-19, political and social issues, have recently been continuous. Machine learning and deep learning technology research are conducted to prevent any damage due to cyber-attacks inducing malicious links to breach personal data. It has been concluded as a lack of basis to judge the attacks to be malicious in previous studies since the features of data set were excessively simple. In this paper, nine main features of three types, "URL Days", "URL Word", and "URL Abnormal", were proposed in addition to lexical features of URL which have been reflected in previous research. F1-Score and accuracy index were measured through four different types of machine learning algorithms. An improvement of 0.9% in a result and the highest value, 98.5%, were examined in F1-Score and accuracy through comparatively analyzing an existing research. These outcomes proved the main features contribute to elevating the values in both accuracy and performance.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.421-421
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• 2021

도시화, 산업화로 인해 하수처리장 유입하수 내 질소 농도가 증가하면서 그에 따른 부영양화 발생, 수생태계에 독성을 미치는 등의 악영향 또한 증가하게 되었다. 하수 내 고농도 질소를 처리하기 위해 1990년 초 연구가 시작되어 현재 보편적으로 사용되고 있는 생물학적 질소 제거 공정은 산소공급과 외부탄소원 보충 과정에서 상당한 비용이 소요된다. 이와 같은 문제점이 대두됨에 따라 고도의 질소 제거 공정이 요구되면서, 경제적으로 개선이 이루어져 기존의 질산화·탈질 공정보다 효율적인 혐기성 암모늄 산화 공정(ANaerobic AMMonium OXidation, ANAMMOX)이 제안되었다. ANAMMOX 공정은 혐기성 조건 아래 전자공여체와 전자수용체로써 암모니아성 질소와 아질산성 질소를 이용해 질소가스 형태로 질소를 제거하는 공정이다. 질산화·탈질 공정과 비교했을 때, 폭기과정에서의 산소요구량 감소, 외부탄소원 불필요, 질소 제거 과정 단축 등의 장점을 가진다. 본 연구는 수처리공정에서의 ANAMMOX 공정의 적용 가능성을 확인하고, 암모니아성 질소대비 아질산성 질소 비율에 따른 Mainstream ANAMMOX 공정의 효율 비교를 통해 공정의 안정성과 높은 제거효율을 확보할 수 있는 NH₄⁺ 대비 NO₂^- 비율을 도출하는데 목적이 있다. 실험실 규모의 Mainstream ANAMMOX 반응조에 적용한 비율은 선행연구를 비롯한 화학양론식에서 제시된 비율을 바탕으로 산정하였다. 1.00부터 1.30의 전체적인 비율을 Initial과 Advanced 2개의 구간으로 나누어 운전한 결과, 각 구간의 NH₄⁺ 제거효율은 각각 58~86%, 94~99%였다. NH₄⁺ 대비 NO₂^- 비율이 증가함에 따라 공정의 안정성이 확보되고, NH₄⁺ 및 총질소(TN) 제거효율이 증가하는 경향이 나타났다. 본 연구의 결과는 수처리공정에서의 안정적인 ANAMMOX 공정 적용을 유도하고, ANAMMOX 공정의 성능개선을 도모하는 연구의 기초로 활용될 수 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.523-533
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• 2009

The purpose of the present study is to examine the dynamic interaction characteristics between moving maglev vehicle and guideway bridge system. For this purpose, the dynamic governing equation of 2-dof maglev vehicle using optimal feedback control scheme of LQG was derived with or without consideration of the dynamic interaction between vehicle and guideway bridge system. From the parametric study, it was found that the dynamic interaction effect between bridge and vehicle was large in case of neglecting the railway roughness effect. But if the railway roughness effect was considered, it was observed two analysis results with or without consideration of the dynamic interaction did not show big difference. As a conclusion, it is required to take into account the dynamic interaction effect of bridge and maglev vehicle and the railway roughness for precise evaluation of runnability of maglev vehicle and impact factor of guideway.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.319-326
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• 2006

A new enhanced 8-node hybrid/mixed plane stress elements based on assumed stress fields and modifed shape functions has been presented. The assumed stress fields are derived from the non-conforming displacement modes, which are less sensitive to geometric distortion. Explicit expression of shape functions is modifed so that it can represent any quadratic fields in Cartesian coordinates under the same condition as 9-node isoparametric element. The newly developed element has been designated as 'HQ8-$14{\beta}$'. The presented element is compared with existing elements to establish its accuracy and efficiency. Over a wide range of mesh distortions, the element presented here is found to be exceptionally accurate in predicting displacements.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.5
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• pp.77-87
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• 2023

Wind turbines playing a critical role in renewable energy generation, accurately assessing their operational status is crucial for maximizing energy production and minimizing downtime. This study conducts a comparative analysis of different neural network models for wind turbine condition diagnosis, evaluating their effectiveness using a dataset containing sensor measurements and historical turbine data. The study utilized supervisory control and data acquisition data, collected from 2 MW doubly-fed induction generator-based wind turbine system (Model HQ2000), for the analysis. Various neural network models such as artificial neural network, long short-term memory, and recurrent neural network were built, considering factors like activation function and hidden layers. Symmetric mean absolute percentage error were used to evaluate the performance of the models. Based on the evaluation, conclusions were drawn regarding the relative effectiveness of the neural network models for wind turbine condition diagnosis. The research results guide model selection for wind turbine condition diagnosis, contributing to improved reliability and efficiency through advanced neural network-based techniques and identifying future research directions for further advancements.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.4-4
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• 2023

다국적 제약회사에서 생산되는 제약화합물은 인간의 질병치료 뿐만 아니라 가축의 생산성을 향상시키는 물질으로도 활발하게 생산되는데 육우의 성장을 촉진하는 기능성 화합물들도 많이 있다. 북미에서 생산되는 소고기의 약 80%가 1번 이상의 성장촉진기술들이 활용되고 있다고 보고된다. 고기소로 생산되는 비육우에 적용되는 방법은 크게 피하 이식에 의해 혈류를 타고 성장을 촉진하는 17β-Estradiol과 합성 남성호르몬제인 Trenbolone acetate가 주로 활용되고, 비육후기 사료에 섞어서 급여하는 사료첨가제 형태인 β2-adrenergic agonist 같은 형태로 적용하게 된다. 근육을 성장하는 기술의 작용기전은 많은 선행연구에 의해 밝혀져 있는 반면 천연 알칼로이드 성분들의 기전은 밝혀진 것이 많지 않다. 한방제재들에서 많이 발견되는 알칼로이드 성분들은 생리활성 기능들을 가진 것으로 알려져 있지만, 생산, 수거, 가공, 추출 등의 공정에서 많은 비용이 발생하므로 비육우의 사료화 가능성은 아주 희박하다. 따라서 비용을 최소화 할 수 있는 후보재료를 검색중에 감자부산물을 확보하였고 기능성 물질의 추출과 사료첨가제 화 하여 비육우에 급여시험을 실시하였다. α-solanine과 α-chaconine은 감자의 잎, 과일 및 괴경에서 발견되는 글리코알칼로이드 화합물로, 쥐, 토끼, 닭과 같은 다양한 동물 모델에서 중독성을 가진 물질로 보고 되고 있다. 최근 연구에서는 비육우의 성능을 유도하는 데 사용되는 것으로 나타났다. 한우 송아지 3마리의 사태(Semimembranosus)와 등심(Longissimus Dorci)근육에서 추출된 근육위성 세포(BSC)에 다양한 수준의 α-solanine(control, 0.001, 0.01, 0.1, 1, 10μM)으로 처리해본 결과 근육관련 지표인 MHC2X과 β2-AR의 발현이 높게 나타난 것을 확인했다. 사료급여실험에서는 대조군에 비해 급여군의 등심단면적과 도체중이 향상되는 것을 확인하였다. 결과적으로 감자유래 농산부산물은 한우 비육우의 근육의 성장을 증가시키고, 그 작용기전은 β2-수용체에 작용하여 단백질 합성을 촉진시켜 근육을 축적시키는 것으로 확인하였다. 농산부산물을 이용한 기능성 사료개발은 최근 이슈가 되고 있는 축산분야 탄소저감을 개선할 수 있는 기술로 축산의 업사이클링 기술로 활용 가능하다.