• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.19-22
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• 2003

Class area is a portion of memory where the constants, fields, and codes of the classes loaded into the Java virtual machine are kept. Knowing the site of the class area is very important especially for embedded Java system with limited memory resources. This paper induces a formula which makes it possible estimate the size of the area. The formula needs some constant values specific to target JVM implementation. We also show that these values can be found using some simple probe classes. An experimental result is included in this paper to confirm the correctness of our approach.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.788-797
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• 2003

Class library is one of the most crucial element of Java runtime environment in addition to Java virtual machine. In particular, embedded Java system depends heavily on the class library due to having a low bandwidth communication link and a small amount of memory which are a common restriction of embedded system. It is therefore quite necessary to find the characteristic of the class library for embedded Java system to build an efficient Java runtime environment. In this paper we have analyzed the characteristic of the class library for embedded system. The analysis includes sorts of classes in the library, typical size of the file which contains the class, and the composition of constant pool which is a major part of the file. We also have found typical number of field and method a class contains, the sizes of stack and local variable array each method requires, and the length of bytecode in the method. The result of this study can be used to estimate the startup time for class loading and the size of memory to create an instance of class which are a mandatory information to design an efficient embedded Java virtual machine.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.177-178
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• 2010

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1794-1797
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• 2003

We developed a web-based virtual laboratory system for electronic circuit experiments on the client/ server distributed environment. Through our virtual laboratory, the learners will be capable of learning 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 suppliers. The proposed virtual laboratory system is composed of four important components: Principle Classroom to explain the concepts and theories of electronic circuit operations, Virtual Experiment Classroom to provide interactive multimedia contents about the syllabus of off-line laboratory class, Assessment Classroom, and Management System. With the aid of the Management System every classroom is organically tied together collaborating to achieve maximum learning efficiency. We have obtained several affirmative effects such as high learning standard, reducing the total experimental hours and the damage rate for experimental equipments.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.547-549
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• 2004

본 논문에서는 IP/MPLS 망에서 QoS 보장형 차별화 서비스 제공을 위한 Virtual Networking 구조를 제안한다. 제안한 구조에서는 멀티미디어 단말장치와 PE(Provider Edge) 사이에서 RSVP-TE를 이용한 signalling을 통해 연결설정을 요청하고 PE에서 CAC(Call Admission Control)가 이루어질 수 있도록 한다. 또한 provider network에서 일반 가입자에게 QoS 보장형 차별화 서비스를 제공해줄 수 있도록 Multiple Virtual Network을 구성하며, class-type별로 차별화된 virtual network을 구성하기 위해서 L-LSP를 PE간에 full-mesh 형태로 설정한다 본 논문에서 제안한 Virtual Networking을 통하며 망 사업자는 보다 효율적으로 망을 관리하며, 통신망 자원의 이용율을 극대화시키고 사용자들에게 QoS 보장형 차별화 서비스를 제공해주는 것이 가능하다.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.397-404
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• 2003

Dedicated-purpose embedded Java system usually takes such model that all class files are converted into a single ROM Image by the ROMizer in the host computer, and then the Java virtual machine in the embedded system executes the image. Defining the ROM Image is a very important issue for embedded system with limited memory resource and low-performance processor since the format directly influences on the memory usage and effectiveness of accessing entries in classes. In this paper we have analyzed the ROMizer and especially the format of the ROM image implemented in the simpleRTJ embedded Jana virtual machine. The analysis says that memory space can be saved up to 50% compared to the original class file and access speed exceeds up to six times with the use of the ROMizer. The result of this study will be applied to develop a more efficient ROMizer for a ROM-based embedded Java system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.278-290
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• 2020

This study evaluated college students' virtual academic experience due to COVID-19. Based on Colaizzi's analysis method, data from advanced interviews with 15 students were analyzed. The results were as follows. The participants showed a desire for eye-level learning, frustration on unsatisfactory academic factors, gratefulness for the factors that enhance academic satisfaction, lonely fight with the shortcomings of online lectures, and the factors predicted by COVID-19, and aim to seek balance through health care. Based on the results, the students should be prepared to learn at an appropriate academic level. Second, the change should be sought to increase delivery and concentration in class. Third, students are motivated by the professor's efforts to communicate in class and their sincerity and passion. Fourth, cooperation between professors and learners is needed to develop a sympathetic and supportive classroom atmosphere. Fifth, until the cessation of COVID-19, the principle of virtual education should persist unless there are exceptional circumstances. These results, which suggested specific ways to increase satisfaction with virtual learning lectures, can be used as basic data for establishing effective virtual teaching directions.

• Journal of Science Education
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• v.46 no.1
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• pp.66-79
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• 2022

This study attempts to find out how science classes using VR content affect students' scientific attitudes and spatial senses. For 4th and 5th graders of an elementary school, a comparative class and an experimental class were set up for each grade, and a total of 11 classes were conducted for each grade. Before and after class treatment, pre- and post-tests were conducted on scientific attitudes and spatial sensations, and interviews with students were conducted during class. After all the classes for the research unit were completed, a survey was conducted to find out the changes in students' perceptions. As results of this study show, it was found that science classes applying virtual reality (VR) content have positive effects on students' scientific attitudes and spatial ability.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.155-162
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• 2021

The purpose of this study were to analyze effects of VR-based intervention on daily living skills and class attitudes of students with intellectual disabilities. To do this, 30 students with intellectual disabilities in the second and third grades of middle school were selected for this study and placed three group. A group took part in a class using only VR program, B group participated in experience activities program, and C group got in the intervention program that combine VR program and experience activities on daily living skills. Intervention programs were conducted 4 times in a week for 4 weeks from the fourth week of July to the third week of August and a class time of each class was 50 minutes. Evaluations were carried out in pre- and post-test. The Evaluation data were analyzed by One-way ANOVA and scheffe'. In Result of study, daily living skills of C group was improved more higher than other groups and class attitudes of C group was improved more higher than group B. These results showed that the intervention combining VR program and direct experience activities was more effective than the other methods.

• Journal of The Korean Digital Architecture Interior Association
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• v.6 no.2
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• pp.17-23
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• 2006

The purpose of this study was to investigate how student felt the strengths and shortness of presentation methods for formation of interior spaces. For this study, the process of the interior architecture design class was divided into three stages: the programming. the design development, and the design completion. In the design development stage, students used presentation methods: hand sketch, scale model, computer modeling, and virtual realty. The strengths of hand sketch was that quick expression. Models provided three-dimensional feelings. Computer modelling provide realistic color and texture. Virtual reality provided three-dimensional immersion and real scale. It is effective that students collect brain storm images using quick hand sketch in the beginning of design development stage. After that, they compose interior spaces in study models with small scale. Watching the models, they design details of spaces by using hand sketch and computer modelling. Using virtual reality, they can check the scale and circulation. Finally, they complete computer modelling by texture mapping and check the final design in virtual reality.