• Journal of Power Electronics
• /
• 제10권4호
• /
• pp.434-443
• /
• 2010

A general purpose experimental set-up has been designed and implemented for students to carry out various experiments on inverters in the power electronics laboratories of universities, during a few hours of laboratory work. This is the first inverter setup that incorporates hardware and software control, as well as an optional user interface in a laboratory experimental set-up of a single multi-purpose inverter, thus making the system versatile and very practical for both undergraduate and graduate students. The system can be controlled either by a computer or through a liquid crystal display (LCD) and a keypad control unit, and it constitutes a low-cost alternative to relatively expensive commercial teaching sets. The computer provides a user friendly interface and easier control for laboratory environments equipped with computers. The LCD and keypad units eliminate the need for a computer, which makes this system usable in the laboratory as a standalone unit as well.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2002년도 하계학술대회 및 세미나
• /
• pp.199-207
• /
• 2002

A virtual laboratory for measurement and instrumentation must aim to realize an integrated environment. To achieve this goal, we designed and implemented a client/server distributed environment and developed a web-based virtual laboratory system for electronic circuits. Since our virtual laboratory system is implemented to describe the on-campus laboratory, the learners can obtain similar experimental data through it. The proposed virtual laboratory system is composed of four important components Principle Classroom, Virtual Experiment Classroom, Evaluation Classroom and Overall Management System. Through our virtual laboratory, the learners will be capable of teaming the concepts and theories related to electronic circuit experiments and how to operate the experimental equipments such as multimeters, function generators, digital oscilloscopes and DC power supplies. Also, every activity occurred in our virtual laboratory is recorded on database and Printed out on the preliminary report form. All of these can be achieved by the aid of the Management System. The database connectivity is made by PHP and the virtual laboratory environment is set up slightly differently for each learner. Finally, we have obtained several affirmative effects such as reducing the total experimental hours and the damage rate for experimental equipments and increasing Loaming efficiencies as well as faculty productivity.

• 대한지구과학교육학회지
• /
• 제13권1호
• /
• pp.53-63
• /
• 2020

본 연구는 2019년도에 적용 2년차를 맞이한 고등학교 과학과 공통과목인 통합과학과 과학탐구실험의 2차 년도 적용 현황을 분석하고 이를 토대로 향후 과학과 고등학교 교육과정 개발을 위한 제언을 도출하는 것을 목적으로 한다. 이를 위해 총244개의 과학중점고와 일반고를 대상으로 설문조사를 실시한 결과를 2018년도 1차 년도 조사결과와 양적으로 비교하였다. 또한 초점집단을 구성하는 9명의 과학교사들과 심층면담을 실시하여 2차 년도 적용현황에 대한 심층 답변을 논의하였다. 연구결과에 따르면, 1차 년도와 마찬가지로 적용 2년차에도 통합과학은 대부분 6~8단위로 운영하고 있었으며, 학급당 통합과학을 담당하는 교사는 3~4명이 대부분인 것으로 나타났다. 교사 초점집단 면담에서 현장교사들은 통합과학이 통합적 지도를 필요로 하며 학생의 흥미와 관심 유발에도 좋지만, 평가공정성 확보 등의 문제로 과정중심 평가 등을 구현하기는 어렵다고 주장하였다. 과학탐구실험의 경우 대부분 학기당 1단위로 2개 학기로 운영하고 있었으며, 가르치는 사람이 달라서 통합과학과 과학탐구실험을 거의 연계하지 않는 것으로 나타났다. 2019년도부터 과학탐구실험의 학교생활기록 기재 방식이 절대평가로 변경되어서 상대평가로 성적산출을 하지 않아도 되므로 학생들의 만족도나 수업의 흐름이 기대한 것보다 훨씬 좋고, 부담없이 가르칠 수 있다고 교사들은 말하였다. 연구결과를 토대로 과학과 공통과목인 통합과학과 과학탐구실험 교육과정 안착을 위한 지원방안, 차기 과학과 교육과정 개정에서 통합과학과 과학탐구실험 과목의 개선 방안 등을 제안하였다.

• 한국환경보건학회지
• /
• 제36권5호
• /
• pp.343-350
• /
• 2010

This study was performed to investigate laboratory workers' exposures to airborne nanoparticles at a university laboratory where acid treatment experiments were conducted on the surfaces of engineered carbon nanotubes (CNTs). The surface area concentrations, number concentrations, and mass concentrations of airborne nanoparticles were measured at personal breathing zones (PBZs) for various tasks using direct reading instruments. For all three metrics, airborne nanoparticle concentrations during the experiments were higher than background levels measured before and after the experiments for all three metrics. Among the various tasks that were performed as part of these experiments, one task that involved filtering a mixture of acid and CNTs showed the highest concentrations in all three metrics, with concentrations of $116.6\;{\mu}m^2$/cc, 24320 pt/cc, and $9.0\;{\mu}g/m^3$, respectively. Nanoparticle surface area concentrations measured at a representative area fluctuated with those at the PBZs in the laboratory. This result indicates that nanoparticles generated during the experiments were not just limited to the PBZs of the workers but were also present throughout the room, potentially exposing co-located workers. CNTs were detected by a transmission electron microscope in an air sample collected while handling the CNTs. All the tasks were performed inside fume hoods, with the sliding sashes open to their required heights. It was noted that the capture velocities of the fume hoods were much lower than the American National Standards Institute (ANSI)'s recommendation level (0.4 to 0.6 m/s). In conclusion, this study showed that, due to inadequate control, laboratory researchers performing acid treatment experiments on surfaces of CNTs were exposed to airborne nanoparticles generated during the tasks.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
• /
• pp.348-351
• /
• 2005

In this study, solute breakthrough curves through the unsaturated zone were predicted using artificial neural network (ANN) by numerical tests and laboratory experiments. In the numerical tests, applicability of ANN model to prediction of breakthrough curves was evaluated using synthetic data generated by HYDRUS-2D. An appropriate strategy of ANN application and input data form were recommended. The ANN model was validated by laboratory experiments comparing with HYDRUS-2D simulations. The results show that the ANN model can be an effective method for forecasting solute breakthrough curves through the unsaturated zone when hydraulic data are available.

• 한국동물생명공학회지
• /
• 제37권1호
• /
• pp.13-16
• /
• 2022

The use of animals heavily impacts the mental health of researchers performing the animal experiments. The animal researchers need to take care of animals but also give pain and sacrifice them at the same time. This circumstance can cause a variety of mental stress to the researchers. The stress generated in the laboratory would not only negatively affect the management of animals and the research results, but also would harm the researchers' physical and mental health. Because the feeling of sympathy for animals is a natural feature of humanity, psychological stress following a laboratory animal's death after use is not surprising. It is necessary to revise the relevant laws based on understanding the difficulties of animal researchers in society and to develop related educational programs at the national level to help the psychology and emotions of researchers who conduct animal experiments.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제13권1호
• /
• pp.877-888
• /
• 2021

The water entry behaviors of projectiles with different cone-headed angles were studied numerically, experimentally and theoretically, mainly focusing on the hydrodynamic impact in the initial stage. Based on MMALE algorithm, it was proposed a formula of impact deceleration, which relied on the initial entry velocity and cone-headed angle. Meanwhile, in order to verify the validity of the simulation model, experiments using accelerometer and high-speed camera were carried out, and their results were in a good agreement with simulation results. Also, theoretical calculation results of cavity diameter were compared with experiments and simulation results. It was observed that the simulation method had a good reliability, which would make forecast on impact deceleration in an engineering project.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
• /
• 제22권1호
• /
• pp.1.2-5
• /
• 1994

Ionospheric sounding experiments have been conducted at RRL (Radio Research Laboratory), Ministry of Communications, using Digisonde 256 since its installation in 1990. Routine observations of the vertical sounding are carried out 48 times (or 39 times) a day, at every 24 hour. In addition, we also made oblique sounding experiments to obtain the real time data of Maximum Usable Frequency (MUF) and detect the anomalous HF propagation, as a part of the joint study between RRL and CRL (Communications Research Laboratory) of Japan. The two stations involved in the study were Anyang (RRL, Korea) and Kokubunji (CRL, Japan). The ionosondes used in both stations were Digisonde 256, developed by ULCAR (University of Lowell, Center for Atmospheric Research), U. S. A. , and the synchronization of time was accomplished with the help of GPS receiver. During most part of the experiments RRL transmitted non-modulated pulses, and CRL received them. The experiment was scheduled from October 25 through October 29, 1993. However, the ionosphere was not developed well enough to conduct the experiment with pre-set operation parameters. The experiment became successful (from 0500 UT to 0800 UT, October 29) only after the operation parameters had been changed, and the continuous ionograms were obtained by CRL at 0718 UT and 0733 UT in October 29, 1993. We believe this type of experiment will ensure the qualitative enhancement of solar-terrestrial physics research and a routine observation of the oblique ionospheric sounding. In this report, we present the results of the fore-mentioned oblique sounding as well as the vertical sounding results obtained by Digisonde 256 at Anyang station of RRL.

• 한국축산식품학회지
• /
• 제42권4호
• /
• pp.609-624
• /
• 2022

Tenebrio molitor larvae, as known as edible insects, has advantages of being rich in protein, and has been recognized as a suitable alternate protein source for broiler and pig feed. Moreover, given their ability to biodegrade polystyrene, a major pollutant, Tenebrio molitor larvae has been proposed as an innovative solution to environmental problems. In the present study, we investigated the toxicity of Tenebrio molitor larvae powder (TMlp) ingested with expanded-polystyrene (W/ eps) through in vitro and in vivo experiments. The objective of this study was to determine whether TMlp W/ eps can be applied as livestock alternative protein source. For in vitro experiments, cytotoxicity test was performed to investigate the effects of TMlp-extract on the viability of estrogen-dependent MCF-7 cells. The possibility of estrogen response was investigated in two groups: Expanded-polystyrene-fed (W/ eps) TMlp group and without expanded-polystyrene-fed (W/o eps) TMlp group. For in vivo experiments, The male Sprague-Dawley rats were divided based on the dosage of TMlp administered and oral administration was performed to every day for 5 weeks. A toxicological assessments were performed, which included clinical signs, food consumption, body and organ weights, hematology, serum chemistry, and hematoxylin and eosin staining of liver and kidney. There were no specific adverse effect of TMlp W/ eps-related findings under the experimental conditions of this study, but further studies on both sexes and animal species differences should be investigated. In conclusion, TMlp W/ eps was considered non-toxic and observed to be applicable as an alternative protein source for livestock feed.

• Journal of Power Electronics
• /
• 제10권6호
• /
• pp.579-586
• /
• 2010

This paper presents the organisation and the technical structure of a remote controlled laboratory in the field of high dynamic drives and motion control. It is part of the PEMCWebLab project with the goal of providing students with practical experience on real systems in the field of power electronics and drives. The whole project is based on clear targets and leading ideas. A set of experiments can be remotely performed on a real system to stepwise identify a two axes positioning system and to design different cascaded control loops. Each single experiment is defined by its goals, the content of how to achieve them, and a verification of the results as well as the achieved learning outcomes. After a short description of the PEMCWebLab project, the structure of the remote control is presented together with the hardware applied. One important point is error handling as real machines and power electronics are applied. Finally, a selection of experiments is presented to show the graphical user interface and the sequence of the laboratory.