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Journal of the Japanese Society of Technology Education

Vol. 39, No. 4

 

 

Original Papers

 

Development of a Digital Signal Processing Type AC Phase Control Circuit.

 

Haruyoshi AKIBA, Yoshinori SUYAMA

 

Abstract

In this investigation, we developed an AC phase control circuit consisting of digital signal processing techniques. This scheme detects a half period of source voltage with a counter and a phase control angle a (alpha) which is determined by calculating the digitized numeric value obtained from the counter in a single board computer. A phase control angle command has been provided from the personal computer to the single board computer by using a printer interface. Consequently, the phase control angle a (alpha) automatically follows the source frequency which ranges from 8 to 165 Hz based on commands from the personal computer . Therefore , when using this equipment with commercial frequencies (50 Hz or 60 Hz), this equipment can digitally perform the phase control with the accuracy of the order of 0.7(degrees) and without changing the hardware or the software.

 

Key words : Digital signal processing , Single board computer ,Personal computer , AC phase control

 

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The Transmission Characteristics and a Design for a Chebyshev-Type Low-Pass Filter with Complex Poles

 

Junji FURUYA, Motoharu HAYASHIKAWA

 

Abstract

A design and the transmission characteristics for a low-pass filter which has Chebyshev-type attenuation characteristics and complex poles on the complex frequency plane is presented. When comparing to circuits of the same order, this low-pass filter is an improvement over an ordinary Wegner-type low-pass filter or a conventional Chebyshev-type low-pass filter with regard to the delay characteristics ( the linear phase characteristics ). In addition, it has better slope characteristics than the Wagner-type low-pass filter . The ordinary Chebyshev function used in a lumped-element circuit was developed into a new type Chebyshev function which has conjugate complex poles ( four poles ) both in the right half and in the left half of the complex frequency plane. We obtained an attenuation amount and an amplitude function for the low range filter motion. We calculated this and arrived at the design formula for the low-pass filter which fulfilled the specifications. A design based on actual specifications for this low-pass filter is provided. The circuit was realized with an active circuit using IC operational amplifiers.

Key words: low-pass filter, complex poles, delay characteristics, attenuation characteristics, IC operational amplifier, circuit synthesis

 

 

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Development of a Teaching Tool which Measures the Surface Roughness of Metals: A Simple Surface Roughness Meter Using a Semiconductor Laser

 

Toshikazu YAMAMOTO, Ryoya MAKINO, Masahiro UEDA

 

Abstract

In the junior high school metal working area of the Industrial Arts and Home Making program the final process of material production is, in many cases, a surface treatment such as painting. This is a very important process because making the metal surface smooth will protect the surface from corrosion, and further, give it beauty. The process of surface treatment starts with rough sandpaper and gradually progresses to finer sand paper until the surface looks glossy. It is of fundamental importance for students to develop the ability to evaluate the finished condition of the surface by looking at it or touching it. It is difficult, however, for beginning students to precisely evaluate the condition of the surface using sight and touch only. Therefore, a teaching tool that assists the students in determining the degree of polishing at the completion of each step is desirable. We developed a simple surface roughness meter to quantitatively measure the degree of surface roughness, and conducted an experimental lesson using it. The concept behind this teaching tool involves measuring the surface roughness in a simple way by pointing the irradiated laser light (from a semiconductor laser) on the surface and measuring the intensity of the reflected light. This teaching tool has made it possible for students to make a numerical estimation and therefore a pertinent evaluation of the surface roughness. Using this device, student products have made remarkable improvement and efficient exercises have become possible. The method of producing this tool is also described for the benefit of those who would like to make one.

Key words: metal working, surface roughness, semiconductor laser, evaluation of product

 

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Development of Computer Assisted Learning Teaching Materials that Focused on a Systematic Approach to Teaching Optics

 

Shin-ichi OKUNO, Kazuto TAKAHASHI, Momoko ARAI, Kiichiro KAGAWA, Kiichiro UEDA

 

Abstract

Currently, the contents of Optics is covered in Elementary School, Junior High School and Senior High School. The instruction, however, is not necessarily linked between schools or across subjects, since each school and subject area deal with the content independently. We, therefore, developed CAL (Computer Assisted Learning) teaching materials which focuses on a systematic approach to the content of optics. That is, we proposed an organizational structure in order to systematically teach the content of optics. This structure was based on Hyper Card (Ver. 2.2). We constructed the teaching materials from which pupils learn about the characteristics of light, light energy, and the application of light. We selected 15 items as the "home stacks". The teaching material consisted of a total of 488 cards and the capacity was 18.5 MB. Explanations of the characteristics of light energy, and applications, plus questions, answers, and experimental methods were written on the structured cards within the stacks. We also included some experimental results to support the teaching material and to make it better. The subjects' self-evaluation following the utilization of theses teaching materials was very positive.

 

Key words :optics, HyperCard, computer assisted learning, laboratory-based teaching material

 

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Technical Information

 

The Development of a Teaching Aid for Teaching the Stroke Order of Chinese Characters Using an Authoring Tool

 

Akihiro JKAWASHIMA, Takamasa ASAI

 

Abstract

We selected the written stroke order of Chinese characters as a theme for developing a multimedia teaching aid in the junior high school information basics class. In order to develop a good quality multimedia teaching aid it is not enough to have a good authoring tool. It is also necessary to have an appropriate theme, an overall structure, balance, comprehensive forms of expression, and sensitivity on the part of the producer. Software that shows the stroke order used when writing Chinese characters was developed through the use of moving pictures and sound. The software includes the 1006 characters which are used in junior school. Using only the mouse, one can study the order for making strokes in a dynamic way. The software has 146 MB which is stored on a CD-ROM. We are discovering that this software has applications in junior high school handwriting classes (Shosha) and at Japanese universities for foreign.

 

Key words : multimedia teaching aids, CAI, Kanji, Chineses character stroke order

 

 

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An Analysis of the Current Status of Fundamental Courses Related to Information [Technology] in a Comprehensive Program of Study

 

Takeshi HONGO, Akira KIKUCHI

 

Abstract

Fundamental courses related to information technology are required courses in a comprehensive program of study. These courses are highly likely to contain material related to basic information technology which students in all disciplines are expected to learn. Therefore, it is the focus of attention when we consider information technology education as general education in the upper secondary schools. We conducted a study using questionnaires. The goal was to determine the current status of this subject and the content of these courses. In addition we inquired into information technology related education in the upper secondary schools. Through this research we learned that the teachers who are in charge of comprehensive programs of study think that "fundamental courses related to information technology" can be applied to a general education program or a technical education program. In addition, teachers understand the educational content of information technology in a comprehensive program of study. In terms of the educational content in a comprehensive program of study, teachers consider "hardware" and "multimedia and socialization" to be common concepts. We also learned that teachers place a relatively high degree of importance on the content which addresses the use of the computer as a tool. They valued the computers as a tool used for the expression of thoughts and because they are convenient. It also became clear that the continuity between information basics in junior high school and high school is not always effectively maintained.

 

Key words: fundamental courses, information technology, comprehensive program. technical education program