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Vishara Jayasekara,민경호,노정훈,김민태,서정민,이호용,황병복 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.2
This article describes the joining of thin metal sheets by a single stroke clinching process. Elastic-plastic and rigid-plastic finite element analysis were applied by employing Coulomb friction and constant shear friction in order to investigate the behavior of the clinch joint formation process. Four process variables, such as die diameter, die depth, groove width, and groove corner radius were selected to investigate the parametric effect on the clinch joint. The strength of clinch joints were evaluated by examining the separation strengths,such as peel strength and tensile shear strength, respectively. A failure diagram was constructed that summarizes the analysis results. The simulation results showed that die diameter and depth were the most decisive parameters for controlling the quality of the clinch joint, while the bottom’s thickness was the most important evaluation parameter to determine the separation strengths.
Enhanced Thermal Performance of Absorption Chillers Fired by Multiple Dynamic Heat Sources
Saliya Jayasekara,Jayantha Siriwardana,Saman Halgamuge 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
The main concept of combined cooling, heating and power (CCHP) generation systems, which produce three energy commodities simultaneously, is based on using absorption chillers fired by the waste heat from the engine instead of electricity for air conditioning or for any other cooling purpose where electricity could have been used. Proper selection and design of the heat recovery system plays an important and challenging role in achieving this goal. Minimum exergy destruction in the waste heat recovery process increases the thermal performance. This paper introduces the modulating flow cascade heat recovery system (CHRS) to improve the coefficient of performance (COP) of the absorption chiller at part load engine operation. Due to this novel feature, it is possible to obtain a percentage increase of over 13% in COP at 50%engine load compared to the conventional fixed flow waste heat recovery.
Shanika N. Jayasekara(메쓰캄카남즈사니카닐란가니자야세카라),Wook H. Na(나욱호),Abdulhameed B. Owolabi(오우라비압둘하메드바바툰데),Jong W. Lee(이종원),Adnan Rasheed(라쉬드아드난),Hyeon T. Kim(김현태),Hyun W. Lee(이현우) (사)한국생물환경조절학회 2018 생물환경조절학회지 Vol.27 No.1
본 연구는 공기주입 이중피복온실과 관행 이중피복온실의 생육환경과 단열성능을 비교하기 위하여 수행하였다. 두 온실의 온도, 상대습도, 포차, 이산화탄소농도, 일사량, 딸기 생산량 및 난방연료소비량을 비교하였다. 공기주입온실이 관행온실보다 야간에 상대습도가 더 높고 포차는 더 낮게 나타나 딸기의 생육에 좋지 않은 환경을 보여주었다. 이산화탄소농도는 공기주입온실이 관행온실보다 더 높게 나타났으며, 이는 공기주입온실이 더 밀폐되어 있어 환기량이 적기 때문인 것으로 판단된다. 관행온실의 광투과율이 77%로 공기주입온실의 72%보다 더 높아 관행온실의 광환경이 더 우수한 것으로 나타났다. 관행온실의 딸기 생산량이 더 높게 나타났으며, 이는 관행온실의 생육환경이 공기주입온실보다 더 우수한 결과로 판단된다. 난방연료는 공기주입온실에서 더 적게 소모되어 공기주입온실의 단열성능이 더 우수한 것으로 나타났다. This study was conducted to determine which greenhouse provided good environmental conditions for strawberry production, and performed better at conserving energy. Temperature, RH, VPD, CO₂, solar radiation, yield, and fuel consumption were the parameters analyzed. The temperatures of both greenhouses were well controlled in order to provide optimal day and night temperatures for strawberry production. The air inflated double layer greenhouse had higher RH values (more than 90% at night), which led to higher disease occurrence, in comparison to the conventional double layer greenhouse. Furthermore, the air inflated double layer greenhouse had lower VPD values than the conventional double layer greenhouse. Therefore, better RH and VPD were observed in the conventional double layer greenhouse. Higher CO₂ concentration was observed in the air inflated double layer greenhouse while the conventional double layer greenhouse ventilated better than the air inflated greenhouse, because of its side ventilators. Moreover, higher solar radiation in the conventional double layer greenhouse resulted in higher yield, in comparison to the air inflated double layer greenhouse. Thus, we can conclude that the conventional double layer greenhouse provided a better environment for crop growth, in comparison to the air inflated double layer greenhouse. Regarding fuel consumption, the air inflated double layer greenhouse had lower fuel consumption than the conventional double layer greenhouse. Therefore, from an energy consumption point of view, we can conclude that the air inflated double layer greenhouse performed better than the conventional double layer greenhouse.
Evaluating Fuzzy Voice Commands by Internal Rehearsal for Controlling a Robot Manipulator
A.G. Buddhika P. Jayasekara,Keigo Watanabe,Kiyotaka Izumi 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper proposes a method fore valuating fuzzy voice commands(FVCs) by internal rehearsal. The robot’s experience on previous movements is very useful forunder standing fuzzy linguistic information. Therefore, an internal rehearsal system is introduced to acquire the robot’s experience on previous movements. Such acquisition enhances the robot’s capability to interpret fuzzy linguistic information in FVCs according to the current environmental context The proposed system is used to evaluate the fuzzy linguistic information related to the primitive movements of a robot manipulator. Those primitive movements are realized by behavior evaluation network(BEN) with the guidance of the internal rehearsal system. Mainly, the system is utilized to understand fuzzy voice motion commands(FVMCs) and fuzzy voice joint commands(FVJCs) for controlling the end-effect or movements and the single joint movements of the robot manipulator. The proposed idea is demonstrated with a PA-10 robot manipulator.
Evaluating Fuzzy Voice Commands by User Guided Visual Attention for Controlling a Robot Manipulator
A.G. Buddhika P. Jayasekara,Keigo Watanabe,Kiyotaka Izumi 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper proposes a method for evaluating fuzzy voice commands(FVCs) by user guided visual attention. FVCs inherit fuzzy linguistic information due to the inclusion of fuzzy linguistic terms such as “verylittle.” The contextual meaning of such information depends on the environmental arrangement. Therefore, visual attention system(VAS) is utilized to evaluate the fuzzy linguistic information based on the environmental conditions. It is implemented by assuming that the corresponding distance value for aparticular FVC depends on the spatialar rangement of the surrounding object in the environment. A fuzzy logic based voice command evaluation system(VCES) is proposed to assess the fuzzy linguistic information in user commands. In addition, the user has been given the freedom to adjust command evaluation process by changing the attention level. It is achieved by using attentive voice commands such as “move carefully.” A situation of object manipulation by navigating the tip of a robot manipulator through the user’s working space is demonstrated to illustrate the sysem where a PA-10 robot manipulator is used.
Nilesh Suriyarachchi,Peshala G. Jayasekara,Takashi Kubota 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
Pose tracking for outdoor rovers is generally a complex task which is further complicated in conditions where a Global Positioning System (GPS) signal is denied such as in planetary exploration, underground mines and covered areas. In these conditions the rover’s pose needs to be calculated purely based on the rover’s current environment observations. However, conventional wheel odometry is not reliable on rough terrain where wheels are prone to slip and the wheels do not have a common plane of motion due to suspension systems. This paper proposes a Fast State Variable Extension (Fast-SVE) method in which 2D state variables (x; y; yaw) are extended to the full 3D state (x; y; z; roll; pitch; yaw) to achieve effective real time 3D pose tracking of the rover. A particle filter implementation incorporating the Fast-SVE method is used to track the 3D pose of the rover with roll and pitch values used for weighting. An Enhanced Motion Model (EMM) is also proposed to further improve the accuracy of 2D pose prediction in the particle filter.
메쓰캄카남즈사니카닐란가니자야세카라,나욱호,오우라비압둘하메드바바툰데,이종원,라쉬드아드난,김현태,이현우,Jayasekara, Shanika N.,Na, Wook H.,Owolabi, Abdulhameed B.,Lee, Jong W.,Rasheed, Adnan,Kim, Hyeon T.,Lee, Hyun W. The Korean Society for Bio-Environment Control 2018 생물환경조절학회지 Vol.27 No.1
본 연구는 공기주입 이중피복온실과 관행 이중피복온실의 생육환경과 단열성능을 비교하기 위하여 수행하였다. 두 온실의 온도, 상대습도, 포차, 이산화탄소농도, 일사량, 딸기 생산량 및 난방연료소비량을 비교하였다. 공기주입온실이 관행온실보다 야간에 상대습도가 더 높고 포차는 더 낮게 나타나 딸기의 생육에 좋지 않은 환경을 보여주었다. 이산화탄소농도는 공기주입온실이 관행온실보다 더 높게 나타났으며, 이는 공기주입온실이 더 밀폐되어 있어 환기량이 적기 때문인 것으로 판단된다. 관행온실의 광투과율이 77%로 공기주입온실의 72%보다 더 높아 관행온실의 광환경이 더 우수한 것으로 나타났다. 관행온실의 딸기 생산량이 더 높게 나타났으며, 이는 관행온실의 생육환경이 공기주입온실보다 더 우수한 결과로 판단된다. 난방연료는 공기주입온실에서 더 적게 소모되어 공기주입온실의 단열성능이 더 우수한 것으로 나타났다. This study was conducted to determine which greenhouse provided good environmental conditions for strawberry production, and performed better at conserving energy. Temperature, RH, VPD, $CO_2$, solar radiation, yield, and fuel consumption were the parameters analyzed. The temperatures of both greenhouses were well controlled in order to provide optimal day and night temperatures for strawberry production. The air inflated double layer greenhouse had higher RH values (more than 90% at night), which led to higher disease occurrence, in comparison to the conventional double layer greenhouse. Furthermore, the air inflated double layer greenhouse had lower VPD values than the conventional double layer greenhouse. Therefore, better RH and VPD were observed in the conventional double layer greenhouse. Higher $CO_2$ concentration was observed in the air inflated double layer greenhouse while the conventional double layer greenhouse ventilated better than the air inflated greenhouse, because of its side ventilators. Moreover, higher solar radiation in the conventional double layer greenhouse resulted in higher yield, in comparison to the air inflated double layer greenhouse. Thus, we can conclude that the conventional double layer greenhouse provided a better environment for crop growth, in comparison to the air inflated double layer greenhouse. Regarding fuel consumption, the air inflated double layer greenhouse had lower fuel consumption than the conventional double layer greenhouse. Therefore, from an energy consumption point of view, we can conclude that the air inflated double layer greenhouse performed better than the conventional double layer greenhouse.
오우라비압둘하메드바바툰데,이종원,메쓰캄카남즈사니카닐란가니자야세카라,이현우,Owolabi, Abdulhameed B.,Lee, Jong W,Jayasekara, Shanika N.,Lee, Hyun W. The Korean Society of Agricultural Engineers 2017 한국농공학회논문집 Vol.59 No.5
A model was developed using Artificial Neural Networks (ANNs) based on Principal Component Analysis (PCA), to accurately predict the air humidity inside an experimental greenhouse located in Daegu (latitude $35.53^{\circ}N$, longitude $128.36^{\circ}E$, and altitude 48 m), South Korea. The weather parameters, air temperature, relative humidity, solar radiation, and carbon dioxide inside and outside the greenhouse were monitored and measured by mounted sensors. Through the PCA of the data samples, three main components were used as the input data, and the measured inside humidity was used as the output data for the ALYUDA forecaster software of the ANN model. The Nash-Sutcliff Model Efficiency Coefficient (NSE) was used to analyze the difference between the experimental and the simulated results, in order to determine the predictive power of the ANN software. The results obtained revealed the variables that affect the inside air humidity through a sensitivity analysis graph. The measured humidity agreed well with the predicted humidity, which signifies that the model has a very high accuracy and can be used for predictions based on the computed $R^2$ and NSE values for the training and validation samples.