• Journal of the Korea Society of Computer and Information
• /
• v.5 no.2
• /
• pp.7-13
• /
• 2000

I propose implementation-based class testing technique based on the test adequacy criterion of an object-oriented program. Considering inter-data member dependences and a set of axioms for test data adequacy, it generates sequences of methods as test cases which satisfy a flow graph-based testing criterion. For a derived class testing. it considers inheritance relationship and the resuability of the testing information for its parent classes which verified the reduction of test cost through the experiment.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.4
• /
• pp.394-399
• /
• 2015

Because flow uniformity affects the life cycle and performance of the catalyst, it is an important design factor for selective catalytic reduction (SCR) systems. We examined how the diffuser angle and the area ratio of the inlet of the SCR reactor to the front of the catalyst affect flow uniformity. For the numerical analysis, we used STAR-CCM+, a common CFD software program. Analysis results showed that the larger the area ratio was, the less the flow uniformity was, and that the longer the diffuser length was, the greater the flow uniformity was. When the area ratio was greater than 1:5, the flow uniformity appeared very similar at the front of the catalyst. As a result, the spread time of the exhaust gas increased and the flow velocity decreased.

• Journal of Digital Convergence
• /
• v.16 no.8
• /
• pp.373-380
• /
• 2018

The purpose of this study was to know the effects of teaching behavior type of expression activity class on flow and competence in elementary school. The subject for this research consisted of elementary students located in Busan were selected as a population. The sampling method was convenience sampling out of non-probability sampling method. A total of 300 questionnaires were distributed and 280 copies were collected back. Out of those returned questionnaires, insincerely replied or double-replied questionnaires were excluded and finally 216 questionnaires were analyzed for this study. Collected data were put to frequency analysis, exploratory factor analysis reliability analysis, correlation analysis, and multiple regression analysis using the SPSS Win Ver. 22.0 program. The results of these analyses are as follows. First, the commanding type, the autocratic type, the democratic type and the reward type which are the subordinate variables of the teaching behavior type, were all found to have significant effects on the flow. Second, the democratic type and the reward type which are the subordinate variables of the teaching behavior type, were found to have significant effects on the competence. But, the commanding type and the autocratic type which are the subordinate variables of the teaching behavior type, were not found to have significant effects on the competence. Third, the flow were found to have significant effects on the competence.

• Journal of Korean Society on Water Environment
• /
• v.26 no.2
• /
• pp.208-214
• /
• 2010

This study aimed at the introduction of desktop method for assessment of environmental flows developed by International Water Management Institute (IWMI) recently and its application to Geum river basin. This scheme simulated the influence on aquatic ecosystem caused by watershed development and in turn the decrease of water quantity keeping the river's own flow regime. It was found to be as very effective method although it had simple structure. Flow duration curves for different environmental classes at Sutong and Gongjoo sites were estimated according to the natural conditional scenario of Geum river basin and the results were relatively compared well with the previous studies. The behaviors of monthly average runoff time series of both sites showed the level of A class. The results of this study would provide the fundamental data to establish the future plans of monitoring or management for aquatic ecosystem of Geum river basin.

• Proceedings of the KIEE Conference
• /
• 1987.07b
• /
• pp.1174-1177
• /
• 1987

The design of flow control protocols for integrared networks with complete voice traffic on the data link level is investigated. The class of admissible flow control policies analyzed maximized the average data link throughput subject to an average system time delay constraints a finite intervals (O,s). In particular, it is shown that the optimum control law is bang-bang (window flow mechanism). The window size L can be analytically derived from maximum tolerated time delay T, the input arrival C of the queueing system, the duration of the time interval S, the initial number of packets in the queue.

• The KSFM Journal of Fluid Machinery
• /
• v.14 no.2
• /
• pp.41-46
• /
• 2011

This study investigated the changes in performance and operating characteristics of an F-class gas turbine according to the change of working fluid from air to carbon dioxide. The revised gas turbine is the topping cycle of the semi-closed oxy-fuel combustion combined cycle. With the same turbine inlet temperature, the $CO_2$ gas turbine is expected to produce about 85% more power. The main contributor is the greater compressor mass flow and the added oxygen flow for the combustion. Compressor pressure ratio increases about 50%. However, the gas turbine efficiency reduces about 10 %. Modulation of inlet guide vane to reduce the compressor inlet mass flow, the major purpose of which is to reduce the compressor inlet Mach number, was also performed.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1888-1891
• /
• 1996

Recently, FLIC(Fluid In Cell) method has been widely used for the compressible. flow computation. A program which adopts the FLIC method and can analyze the flow conditions with arc in the interrupter was developed in our team. It was applied to the 800kV class gab circuit breaker for flow conditions with arc, and the results are presented and discussed in this paper.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.445-451
• /
• 2004

Four design candidates for a 1.4MW class partial admission turbine have been chosen from a Preliminary design process. Their performance were estimated through the 3-D numerical analyses using a frozen rotor method. In order to select the optimum design, each flow analysis result was compared with others. Flow characteristics in the passages and some types of losses induced by shocks and wakes were found from calculation results. Based on these calculations, a new rotor blade was redesigned and compared with previous one through flow analysis.

• Journal of information and communication convergence engineering
• /
• v.18 no.4
• /
• pp.239-244
• /
• 2020

This study analyzed the influencing factors of learning engagement and teaching presence in online programming practice classes. The subjects of this study were students enrolled in an industrial specialized high school, who practiced creating Arduino circuits and programming using a web-based virtual practice tool called Tinkercad. This research adopted a tool that can measure task value, learning flow, learning engagement, and teaching presence. Based on this analysis, learning flow had a mediating effect between task value and online learning engagement, as well as between task value and teaching presence. Increasing learning engagement in online classes requires sensitizing the learners about task value, using hands-on platforms available online, and expanding interaction with instructors to increase learning flow of students. Furthermore, using virtual hands-on tools in online programming classes is relevant in increasing learning engagement. Future research tasks include: confirming the effectiveness of online learning engagement and teaching presence through pre- and post-tests, and conducting research on various practical subjects.

• Progress in Superconductivity and Cryogenics
• /
• v.15 no.3
• /
• pp.35-39
• /
• 2013

In this paper, we present test results of developed 100 W class linear compressor for Stirling-type pulse tube refrigerator. The fabricated linear compressor has dual-opposed configuration, free piston and moving magnet type linear motor. Power transfer, efficiency and required pressure waveform are predicted with designed and measured specifications. In experiments, room temperature test with flow impedance is conducted to evaluate performance of developed linear compressor. Flow impedance is loaded to compressor with metering valve for flow resistance, inertance tube for flow inertance and buffer volumes for flow compliance. Several operating parameters such as input voltage, current, piston displacement and pressure wave are measured for various operating frequency and fixed input current level. Behaviors of dynamics and performance of linear compressor as varying flow impedance are discussed with measured experimental results. The developed linear compressor shows 124 W of input power, 86 % of motor efficiency and 60 % of compressor efficiency at its resonant operating condition.