가전제품의 사용 방법에 따른 전기에너지 소비량 조사

남주석 한국초등과학교육학회 2015 한국초등과학교육학회 학술대회 Vol.68 No.-

흔히 냉장고 문을 자주 열면 전기에너지 소비량이 늘어난다고 한다. 그러나 정말 그런지, 그렇다면 소비량이 얼마나 많이 늘어나는지 알려진 데이터가 없다. 본 워크숍에서는 가전제품의 사용방법의 차이에 따른 전기에너지의 소비량을 조사하는 활동을 소개하고자 한다. 즉, 전력을 실시간으로 측정하고, usb를 통하여 컴퓨터에 저장할 수 있는 전력측정기의 사용법과 이를 통해 얻을 수 있는 데이터를 살펴본다. 또한 전력측정기를 이용하여 가전제품 중 냉장고의 소비전력의 변화양상을 살펴보고, 냉장고 문을 자주 열었다 닫았을 때, 내부의 용량을 채웠을 때 등의 사용 방법 차이에 따른 전력 소비량을 살펴본다. 그리고 냉장고의 전력 소비량을 토대로 하여 다른 가전제품의 전기에너지 소비량과 이에 대한 조사 방법에 대하여 논의하고자 한다.

Tillage Characteristics Estimation of Crank-type and Rotary-type Rotavators by Motion Analysis of Tillage Blades

남주석,김대천,김명호,김대철 한국농업기계학회 2012 바이오시스템공학 Vol.37 No.5

Purpose: This study has been conducted to investigate the applicability of motion analysis of tillage blade for estimation of tillage characteristics of crank-type and rotary-type rotavators. Methods: The interrelation between tillage traces from motion analysis and field test results including rotavating depth, pulverizing ratio and inversion ratio at the same work conditions were analyzed for both crank-type and rotary-type rotavators. The work conditions include working speed of prime mover tractor and PTO speed of rotavators. For the motion analysis, joint conditions of main connecting component were specified considering the actual working mechanism of rotavator. Results: There were important correlations for the trend between motion analysis and field test results. Conclusions: Although further study is needed for applying motion analysis to estimate the accurate tillage related parameters such as rotavating depth, the soil pulverizing ratio and inversion ratio, it could be used to compare the tillage characteristics of various rotavators quickly and simply.

Comparison of Work Performance of Crank-type and Rotary-type Rotavators in Korean Farmland Conditions

남주석,김대철,강영선,김경욱,강대식 한국농업기계학회 2012 바이오시스템공학 Vol.37 No.3

Purpose: This study was conducted to understand the work performance of crank-type rotavators and compare them with those of rotary-type rotavators in Korean farmland conditions. Methods: Tillage operations were carried out using both rotavators with the same nominal rotavating width and rated power. During the operations, PTO speed and torque, actual work speed, and rotavating width and depth were measured. To evaluate work performance, pulverizing ratio, inversion ratio, and specific volumetric tilled soil were calculated and compared for each rotavator. Results: It is found that the crank-type rotavator has better specific volumetric tilled soil performance and deep tillage, while the pulverizing ratio is worse. Conclusions: Crank-type and rotary type rotavator have diffenent properties each other in several work performances. It’s important, therefore, to choose a suitable type of rotavator that satisfy the farmer’s requirements in accordance with the condition of field and the purpose of tillage operation.

Factorial Experiment for Drum-type Secondary Separating Part of Self-propelled Pepper Harvester

남주석,강영선,김수빈,김대철 한국농업기계학회 2017 바이오시스템공학 Vol.42 No.4

Purpose: This study was conducted to determine the appropriate operating conditions through a factorial experiment for the secondary separating part of the self-propelled pepper harvester. Methods: An experimental setup that simulates the secondary separating part of the self-propelled pepper harvester was organized. Test samples were classified into three types according to the number of peppers on a stem, and 12 sets were prepared for each type. Among the operating conditions of the secondary separating part, the rotational speed of drum B (four levels), radial clearance between drums and cylindrical teeth (three levels), and speed ratio between the three drums (two levels) were set as the test factors, and tests were repeated three times for different levels of each factor. The appropriate operating conditions were determined by analyzing the separation ratio and damage ratio of the peppers collected through the secondary separating part. Results: The test factors changed the overall separation ratio and overall damage ratio in similar trends. In other words, the conditions that caused high overall separation ratios also exhibited high overall damage ratios. Owing to the high overall damage ratio in the condition with the highest overall separation ratio, the operating conditions should be selected considering both ratios. Conclusions: When the condition with more than 60% of overall separation ratio and less than 15% of overall damage ratio was considered as the appropriate operating condition, 70 rpm of the rotational speed of drum B, 5 mm of the radial clearance between drums and cylindrical teeth, and 7:3:5 for the speed ratio of the three drums A, B, and C should be applied for the secondary separating part used in this study. Supplementary studies will be required in the future to find optimal operating conditions through the actual field test under further divided test factors.

Development of highly reproducible test rig for pitch and yaw bearings of wind turbine

남주석,한정우,박영준,남용윤,이근호 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.2

Pitch and yaw bearings are essential to the safe and efficient operation of wind turbines. They are classified as a large bearing, and theysuffer from much more severe operational conditions compared to small bearings used for general industrial applications; in particular,they are subjected to greater external forces in each direction, very thin lubrication film thickness during operation, and so on. Furthermore,because they are installed on the wind turbine blade or a tower top of high altitude, it is costly and time consuming to repair orreplace them in the field. Therefore, a laboratory-scale test is required for ensuring the performance of the pitch and the yaw bearingsbefore application in the field. A test rig is developed to verify the performance of the pitch and the yaw bearings, including their fatiguelife and static loading capacity. The test rig can reproduce actual operational conditions such as 6 degree of freedom (DOF) dynamicloadings and rotation of bearings for both directions. The mounting interfaces of the test rig are also the same as those used in the originalenvironment, and various sizes of bearings can be applied by using a changeable adaptor. This high reproducibility of actual loading,driving, and mounting conditions simultaneously as well as applicability to wide size ranges are distinctively advantageous characteristicscompared to previous test rigs. A structural analysis and preliminary friction torque test showed the suitability of the developed rigfor use in pitch and yaw bearings of 2.0-3.0 MW class wind turbines.

A new accelerated zero-failure test model for rolling bearings under elevated temperature conditions

남주석,김형의,김경욱 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6

A method for accelerated zero-failure testing was proposed for rolling bearings at high operational temperature. The life-load relationship of rolling bearings is combined with the Arrhenius model based on a life-temperature relationship on bearing lubricants to take the temperature effect on bearing life into consideration. Testing duration was calculated to demonstrate at least 90% reliability at a designed rating life of rolling bearings with a given confidence level under the service load and temperature conditions. A step by step procedure for calculating equivalent bearing load and speed was also proposed using a data of load distribution duration of bearings. Finally, an example was given for the case of a deep-groove ball bearing.

Application of similarity theory to load capacity of gearboxes

남주석,박영준,김정길,한정우,남용윤,이근호 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

This study suggests the theoretical methodology to construct a small-sized similarity model having the same load capacity as a largegearbox. The prototype gearbox was a 2-MW wind turbine gearbox consisting of two planetary gear stages and one parallel shaft gearstage, and the specifications of its 1/4 scale similarity model were determined by applying similarity theory. The constructed similaritymodel was validated by comparing load capacity parameters with those of the prototype gearbox using analysis tool. The validation resultsshowed that the nominal tooth root and contact stresses of the similarity model and prototype gearbox were identical, whereas thetooth root and contact stresses satisfied the similarity condition within 2% difference. Furthermore, most factors that influenced the toothroot and pitting stress limits were identical. Thus, information related to load capacity, one of the major design evaluation criteria forgears, of large-size gearbox can be replicated by its similarity model. Although this is a theoretical methodology and still has many difficultiesto apply to practical situations, these results have opened up the possibility of applying similarity theory to load capacity of gearboxes. Because the load capacity is the primary cause of commercial gearbox failure, this result also shows the possibility of life similarityin the gearbox application, although some further study is needed.

Measurement of Mechanical and Physical Properties of Pepper for Particle Behavior Analysis

남주석,변준희,김태형,김명호,김대철 한국농업기계학회 2018 바이오시스템공학 Vol.43 No.3

Purpose: This study was conducted to investigate the mechanical and physical properties of a Korean red pepper variety for particle behavior analysis. Methods: Poisson’s ratio, modulus of elasticity, shear modulus, density, coefficient of restitution, and coefficient of friction were derived for “AR Legend,” which is a domestic pepper variety. The modulus of elasticity and Poisson’s ratio were measured through a compression test using a texture analyzer. The shear modulus was calculated from the modulus of elasticity and Poisson’s ratio. The density was measured using a water pycnometer method. The coefficient of restitution was measured using a collision test, and the static and dynamic friction coefficients were measured using a inclined plane test. Each test was repeated 3–5 times except for density measurement, and the results were analyzed using mean values. Results: Poisson’s ratios for the pepper fruit and pepper stem were 0.295 and 0.291, respectively. Elastic moduli of the pepper fruit and pepper stem were 1.152 × 107 Pa and 3.295 × 107 Pa, respectively, and the shear moduli of the pepper fruit and pepper stem were 4.624 × 106 Pa and 1.276 × 107 Pa, respectively. The density of the pepper fruit and the pepper stem were 601.8 kg/m3 and 980.4 kg/m3, respectively. The restitution coefficients between pepper fruits, pepper stems, a pepper fruit and a pepper stem, a pepper fruit and plastic, and a pepper stem and plastic were 0.383, 0.218, 0.277, 0.399, and 0.148, respectively. The coefficients of static friction between pepper fruits, pepper stems, a pepper fruit and a pepper stem, a pepper fruit and plastic, and a pepper stem and plastic were 0.455, 0.332, 0.306, 0.364, and 0.404, respectively. The coefficients of dynamic friction between a pepper fruit and plastic and a pepper stem and plastic were 0.043 and 0.034, respectively.

트랙터 부착형 다기능 작업기의 비용 및 포장능률 비교를 통한 경제성 분석

남주석,김승준,장문경 강원대학교 농업생명과학연구원 2022 강원 농업생명환경연구 Vol.34 No.2

In this study, an economic analysis of the cost and field capacity was conducted to prove the validity of developing and distributing a tractor-mounted multi-working machine. The cases of using a multi-working machine and individual working machines were compared. The results showed that the total hourly cost of the multi-working machine was 308,805 KRW. Compared with individual working machines, the tractor-mounted multi-working machine can save 53.5% of the total hourly cost. The field capacity for the multi-working machine was 12 ares/hour. This is 60.0% higher than that of individual working machines. The cost per 10 ares working area was calculated using the hourly total cost and field capacity. The cost per 10 ares working area for the multi-working machine is 257,337 KRW, meaning that the multi-working machine can save 71.0% of the cost compared with individual working machines. Therefore, it is concluded that the economic validity of the multiworking machine is high.

초등학생 과학 추천도서의 과학 학습에서의 적절성 분석

남주석,전영석 한국초등과학교육학회 2014 한국초등과학교육학회 학술대회 Vol.67 No.-

이 연구에서는 초등학생을 대상으로 하는 과학 추천 도서를 살펴보고 그 특징을 분석하였다. 이를 위해 여러 문헌과 선행연구, 면담 및 의견조사 및 파일럿 테스트를 통하여 검사 도구를 제작하였으며, 과학도서 추천기관에서 추천한 9권의 추천도서를 1권당 3명의 평정자가 검사 도구를 참고하여 검토하고 의견을 반영하여 결과를 도출하였다. 연구 결과는 다음과 같다. 첫째, 추천도서들은 탐구와 과학의 본성 영역에서 다른 영역에 비해 낮은 평가를 받았다. 둘째, 도서에서 다루고 있는 과학 지식과 책의 구성 사이에 적절한 조화가 잘 이루어지지 않았다. 셋째, 편집의 측면에서 일부 도서는 이해하기 쉽고 편하게 읽기에 어려움이 있었다. 이 연구 결과를 토대로, 초등학생과학 추천도서에 대한 교육적 시사점을 도출하여 제시하였다.