• Journal of applied mathematics & informatics
• /
• v.7 no.1
• /
• pp.83-100
• /
• 2000

Many queueing systems such as M/M/s/K retrial queue with impatient customers, MAP/PH/1 retrial queue, retrial queue with two types of customers and MAP/M/$\infty$ queue can be modeled by a level dependent quasi-birth-death(LDQBD) process with linear transition rates of the form ${\lambda}_k$={\alpga}{+}{\beta}k$ at each level $\kappa$. The purpose of this paper is to propose an algorithm to find transient distributions for LDQBD processes with linear transition rates based on the adaptive uniformization technique introduced by van Moorsel and Sanders [11]. We apply the algorithm to some retrial queues and present numerical results.

• Journal of Korea Foundry Society
• /
• v.20 no.3
• /
• pp.197-207
• /
• 2000

Al-Si alloys were solidified in a rotating cylindrical mold by a vertical centrifugal casting process. Under a certain casting condition, there are four distinct zones such as the chill zone, the primary fine columnar zone, the equiaxed zone, and the secondary coarse columnar zone from the mold wall. The columnar-equiaxed transition (CET) and the equiaxed-columnar transition (ECT) were measured as functions of solute content, flow rate (mold velocity), pouring temperature and mold temperature. Within the critical value of solute content, as the flow rate increases, the columnar-equiaxed transition were found, but not the equiaxed-columnar transition. The aspect ratio of the primary columnar zone was more affected by the solute content than the flow rate. However the aspect ratio of the equiaxed zone was more affected by the flow rate than the solute content. The aspect ratio of the secondary columnar zone was affected by both the flow rate and the solute content.

• The Mathematical Education
• /
• v.25 no.1
• /
• pp.1-8
• /
• 1986

It is a common saying that markov-chain is a special case of probability course. That is to say, It means an unchangeable markov-chain process of the transition-probability of discontinuous time. There are two kinds of ways to show transition probability parade matrix theory. The first is the way by arrangement of a rightangled tetragon. The second part is a vertical measurement and direction sing by transition-circle. In this essay, I try to find out existence of procession for transition-probability applied markov-chain. And it is possible for me to know not only, what it is basic on a study of chain but also being applied to abnormal problems following a flow change and statistic facts expecting to use as a model of air expansion in physics.

• Journal of the Korean Society for Heat Treatment
• /
• v.14 no.6
• /
• pp.345-349
• /
• 2001

This study has investigated the effect of thermal stability and mechanical property of $Fe_{80-X}P_{10}C_6B_4M_X$(X=2, 4, 6, M=transition metal) amorphous alloys fabricated by the melt-spun process. The glass transition temperature($T_g$), crystallization temperature($T_x$) and hardness increase with decreasing electron concentration (e/a) from about 7.38 to 7.18. The decrease of e/a implies the increase in the attractive bonding state between the M elements and other constituent element. The decrease in a/e leads to the enhancement of the attractive bonding state among the constituent elements which is favorable for the increase in $T_g$, $T_x$ and hardness.

• Journal of Korean Neurosurgical Society
• /
• v.64 no.3
• /
• pp.367-373
• /
• 2021

Secondary neurulation (SN) is a critical process to form the neural tube in the posterior region of the body including the tail. SN is distinct from the anteriorly occurring primary neurulation (PN); whereas the PN proceeds by folding an epithelial neural plate, SN precursors arise from a specified epiblast by epithelial-to-mesenchymal transition (EMT), and undergo self-renewal in the tail bud. They finally differentiate into the neural tube through mesenchymal-to-epithelial transition (MET). We here overview recent progresses in the studies of SN with a particular focus on the regulation of cell lineage, self-renewal, and EMT/MET. Cellular mechanisms underlying SN help to understand the functional diversity of the tail in vertebrates.

• Journal of Ocean Engineering and Technology
• /
• v.37 no.3
• /
• pp.122-128
• /
• 2023

Autonomous berthing is a crucial technology for autonomous ships, requiring optimal trajectory planning to prevent collisions and minimize time and control efforts. This paper presents a two-phase, two-point boundary value problem (TPBVP) strategy for creating an optimal berthing trajectory for a twin-propeller, twin-rudder ship with autonomous berthing capabilities. The process is divided into two phases: the approach and the terminal. Tunnel thruster use is limited during the approach but fully employed during the terminal phase. This strategy permits concurrent optimization of the total trajectory duration, individual phase trajectories, and phase transition time. The efficacy of the proposed method is validated through two simulations. The first explores a scenario with phase transition, and the second generates a trajectory relying solely on the approach phase. The results affirm our algorithm's effectiveness in deciding transition necessity, identifying optimal transition timing, and optimizing the trajectory accordingly. The proposed two-phase TPBVP approach holds significant implications for advancements in autonomous ship navigation, enhancing safety and efficiency in berthing operations.

• Journal of Gifted/Talented Education
• /
• v.22 no.3
• /
• pp.703-728
• /
• 2012

The purpose of this study was exploring instructive methods to make each gifted child's ability develop as more by selecting the dynamic method instead of existing static method in teaching and evaluating science-gifted students in elementary school and by analyzing conceptual change of electric circuit. In this research, 11 science-gifted students in primary school were chosen, and Dynamic Science Assessment(DSA) intended to comprehension of scientific electric circuit concept was performed as focusing on scaffolding aspects in order to find the transition process. And then, the features on transition process of students' concept were analyzed in quality. The results of the study were checked that the features of useful scaffolding input with respect to comprehending concepts of science gifted-students by using DSA. The less familiar to approach the subjects, the more presented numbers of scaffolding showed. As coming toward transition and same questions, scaffoldings (interactions) were declined because their level of transition was higher than before. Various ways were used in helping the students comprehend the concept on the method of connecting electric circuit and the emitting amount of current, which acted to adapt to daily life.

• Journal of Korean Society of Archives and Records Management
• /
• v.20 no.4
• /
• pp.205-227
• /
• 2020

This paper is a record of the transitioning of the Journal of Korean Society of Archives and Records Management to open access. To understand this process, this paper explains the meaning of the conflict over the copyright among commercial journal aggregators, scholarly societies and public sector aggregators. In addition, this paper explains the declarations for open access transition in scholarly societies in the fields of library and information science and other humanities & social sciences in Korea. This paper records the practices and problems that the scholarly society as a publisher has faced in related to securing the journal publication cost, expanding the channels of distribution, and reforming the regulation of the journal. This paper also attempts to understand this transition process as making a knowledge commons.

• Journal of Technology Innovation
• /
• v.22 no.4
• /
• pp.57-88
• /
• 2014

The 'Grand Challenge' in the global level raises fundamental questions on the role of private firm as a profit maximizer. From the new perspective, firms are recognized as a social entity with social and environmental responsibility. Particularly, the importance of transition-orineted firms, which pursue an objective of socio-technological system transition, have increased. These environmental changes request a new understanding on the identification of firms and the evolution of sustainable business model from the technological innovation perspectives. This paper aims on the new understanding on the motivation of firms who participated on the sustainable system transition and the proposal of 'transition-oriented firms' concept. Based on literature survey, this paper reviews the role of firms in the process of socio-technological system transition, the cases of transition-oriented firm, the types of sustainable business models and their strategies.

• Journal of Korea Technology Innovation Society
• /
• v.22 no.1
• /
• pp.1-27
• /
• 2019

This study deals with the changes in the government-funded research institutes (GRI) in terms of 'responding to social challenges and turning to the institutes that are pursuing sustainability transition'. The newly established societal problem-solving R&D projects in GRIs are core experiments for the transition. In order to discuss about the prospect of transition of GRIs, this study used focus group interview approach. In the interview, the GRIs's stance on the societal problem-solving R&D projects, and its process, problems and the policy direction had been discussed. It is suggested that the necessity of transition is discussed and transition experiments are proceeding on a small scale, but experiments are still underway in the existing framework. In order to facilitate the transition in GRIs, it is necessary to carry out the experiment and the vision making work from the inside the GRI.