• Steel and Composite Structures
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• v.13 no.3
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• pp.239-258
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• 2012

In this paper, experimental investigations on high strength steel (HSS) stud connected steel-concrete composite (SCC) girders to understand the effect of shear connector density on their flexural behaviour is presented. SCC girder specimens were designed for three different shear capacities (100%, 85%, and 70%), by varying the number of stud connectors in the shear span. Three SCC girder specimens were tested under monotonic/quasi-static loading, while three similar girder specimens were subjected to non-reversal cyclic loading under simply supported end conditions. Details of casting the specimens, experimental set-up, and method of testing, instrumentation for the measurement of deflection, interface-slip and strain are discussed. It is found that SCC girder specimen designed for full shear capacity exhibits interface slip for loads beyond 25% of the ultimate load capacity. Specimens with lesser degree of shear connection show lower values of load at initiation of slip. Very good ductility is exhibited by all the HSS stud connected SCC girder specimens. It is observed that the ultimate moment of resistance as well as ductility gets reduced for HSS stud connected SCC girder with reduction in stud shear connector density. Efficiency factor indicating the effectiveness of high strength stud connectors in resisting interface forces is estimated to be 0.8 from the analysis. Failure mode is primarily flexure with fracturing of stud connectors and characterised by flexural cracking and crushing of concrete at top in the pure bending region. Local buckling in the top flange of steel beam was also observed at the loads near to failure, which is influenced by spacing of studs and top flange thickness of rolled steel section. One of the recommendations is that the ultimate load capacity can be limited to 1.5 times the plastic moment capacity of the section such that the post peak load reduction is kept within limits. Load-deflection behaviour for monotonic tests compared well with the envelope of load-deflection curves for cyclic tests. It is concluded from the experimental investigations that use of HSS studs will reduce their numbers for given loading, which is advantageous in case of long spans. Buckling of top flange of rolled section is observed at failure stage. Provision of lips in the top flange is suggested to avoid this buckling. This is possible in case of longer spans, where normally built-up sections are used.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.405-411
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• 2015

Recently, according to the low-carbon green growth policy, the Stirling Engine has been increasing the interest of some sort of external combustion engines Stirling Engine is largely divided into three types ${\alpha}$, ${\beta}$ and ${\gamma}$. Among them, a ${\gamma}$-type engine is easy to design and can be applied variously. However, owing to the connection distance between the cylinder and the crank, there was a problem that ${\gamma}$-type occupies a larger volume than the ${\alpha}$ and ${\beta}$-types. As one of the methods to solve this problem, we have to consider about the Yoke crank which have been applied mainly to the ${\alpha}$-type. Because there are two advantages in not only reduction of engine volume but also parallelizing the cylinder. In this study, leading on from the existing design techniques for the Ross Yoke crank, this paper presents a simple method that can apply the yoke crank design of the ${\gamma}$-type stirling engine.

• Bulletin of the Society of Naval Architects of Korea
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• v.8 no.1
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• pp.67-94
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• 1971

Korean fisheries industry holds 57,255 boats amounting to 269,079 tons in gross as of the end of 1967. The boats of the size under 30G.T., about sixty-two per cent of the total in tonnage, are utilized in coastal and their contribution to the total production of Korean fisheries industry is estimated at over seventy-five percent. Hull forms and construction method of them are partly in transition stage to the western tradition from the oriental tradition, which employs the chine-type straight-framed section, and tick and wide wooden planking fastened on naturally bent timber frames. And only about a half of them are mechanized. About fifty-seven per cent, 7,525 boats amounting to 91,751 gross tons, of the coastal and inshore fishing boats are those of the size ranging 5G.T. to 30G.T., which are engaged mostly in draft-and gill-netting, angling, longlining, anchovy seining, squid fishing and set-netting. The important fishing boats forming main structure of the inshore fishing fleets can be classified as 5G.T.-class multi-purpose boats, 10G.T.-class angling/longlining boats and 20G.T.-class drift-/gill-netters mostly utilized in the east-sea, 15G.T.-class anchovy seiner in the south-sea-sea, 20G.T.- and 28G.T.-class stow-netters in the west sea. Each of the three sea regions, east, south, and west, of Korean water has distinctly different characters from one another in topography, geology and sea aspects, and consequently in marine resources, fishing grounds and fishing tactics desired. Hence, the finishing boats in each sea region have also their own characters in hull form, structural features, deck design and equipments. In this report, analyzing the characteristics of the existing inshore fishing boats ranging 5G.T. to 30G.T. in size from view points of naval architecture and engineering, the author made an integrated investigation of their characteristics, covering size and principal dimensions, hull form, deck design, structural features and mechanization, in close connection with the natural circumstances of Korean water and local techno-socio-economic problems, and, finally, made some suggestions for the rational improvement or modernization of the inshore fishing boats. Further details of the characteristics of Korean inshore finishing boats are referred to the drawings of them compiled by the author and given in the reference[23] listed at the end of this report.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.149-158
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• 2005

This paper proposes a congestion avoidance algorithm which provides stable throughput and transmission rate regardless of buffer size by limiting the TCP congestion window in fixed bandwidth networks. Additive Increase, Multiplicative Decrease (AIMD) is the most commonly used congestion control algorithm. But, the AIMD-based TCP congestion control method causes unnecessary packet losses and retransmissions from the congestion window increment for available bandwidth verification when used in fixed bandwidth networks. In addition, the saw tooth variation of TCP throughput is inappropriate to be adopted for the applications that require low bandwidth variation. We present an algorithm in which congestion window can be limited under appropriate circumstances to avoid congestion losses while still addressing fairness issues. The maximum congestion window is determined from delay information to avoid queueing at the bottleneck node, hence stabilizes the throughput and the transmission rate of the connection without buffer and window control process. Simulations have performed to verify compatibility, steady state throughput, steady state packet loss count, and the variance of congestion window. The proposed algorithm can be easily adopted to the sender and is easy to deploy avoiding changes in network routers and user programs. The proposed algorithm can be applied to enhance the performance of the high-speed access network which is one of the fixed bandwidth networks.

• International Commerce and Information Review
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• v.4 no.1
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• pp.107-128
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• 2002

In order to clarify the relationship between the Internet utilization of the Korean small export firms for export marketing and it's performance, first, a research model and hypothesis have been made on a theoretical basis. This research hypothesis has been examined through gathering survey data and a statistical analysis based on MANOVA. The conclusion, as well as the main point of this thesis, is that, in most cases, there was a significant statistical connection between the variables of export performances and Internet-utilized export marketing strategies, which are both based on the classical AIDA model of effective hierarchy of communication for sales and advertising. This conclusion brings forth a substantial topic as well as provides meaningful implications for the Korean small export firms when putting together a marketing strategy using the Internet. It is also hoped that this will come as a reference for other researchers henceforth. However, there is an issue of lack of representativeness when considering that the samples were chosen on the basis of the convenience sampling method. Another issue may be that a portion of the subjects were not related to actual trade, but were, in fact, Web masters who operated e-trade systems. Furthermore, there are also numerous problems of missing data, and 6 out of the 8 main hypotheses possessed the issue of fitness level with the data. Therefore, in order to enhance both the representative and fitness levels of the data of further research for this topic, future respondents will have to have special trade knowledge, as well as technical knowledge of e-trade. However, unless the Internet begins to greatly contribute to export marketing of corporations, this type of enterprising spirit by corporations in gathering suitable respondents will not surface. Although not used in examining the hypotheses of this particular thesis, the relationship between competitive and circumstantial variables, which were added to the upcoming survey, and export performances will soon be analyzed and announced in order to atone for some of the standards this thesis fell short of.

• Journal of The Korean Association of Information Education
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• v.23 no.6
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• pp.607-619
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• 2019

As software education was introduced through the 2015 revised curriculum, various research activities have been carried out to improve the computational thinking of learners beyond the existing ICT literacy and software utilization education. With this change, the purpose of this study is to examine the research trends of various research activities related to computational thinking which is emphasized in software education. To this end, we extracted the key words from 190 papers related to computational thinking subject published from January 2014 to September 2019, and conducted frequency analysis, word cloud, connection centrality, and topic modeling analysis on the words. As a result of the topical modeling analysis, we found that the main studies so far have included studies on 'computational thinking education program', 'computational thinking education for pre-service teacher education', 'robot utilization education for computational thinking', 'assessment of computational thinking', and 'computational thinking connected education'. Through this research method, it was possible to grasp the research trend related to computational thinking that has been conducted mainly up to now, and it is possible to know which part of computational thinking education is more important to researchers.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.357-368
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• 2017

To establish new metal groundwater standard, 5 metals such as aluminum, chromium, iron, manganese, and selenium were evaluated by Chemical Ranking Of groundWater pollutaNts (CROWN) including possibility of exposure, toxicity, interest factor, connection standard for other media, and data reliability. 430 groundwater samples in 2013 and 2014 were collected semiannually from 110 groundwater wells and they were analyzed for selenium, manganese, iron, chromium, and aluminum. For this study, 430 groundwater samples were categorized into 3 geological distribution features, such as igneous, metamorphic, and sedimentary rock region and geological background levels were divided by pre-selection methods. For the results, the average concentrations of aluminum, chromium, iron, manganese, and selenium in 430 groundwater samples were $0.0008mg\;L^{-1}$, $0.0001mg\;L^{-1}$, $0.174mg\;L^{-1}$, $0.083mg\;L^{-1}$, and $0.0004mg\;L^{-1}$, respectively. In addition, among various geologies, average concentration of selenium was the highest in igneous rock region, average concentrations of chromium, manganese and aluminum were the greatest in sedimentary rock region, and average concentration of iron was the most high in metamorphic rock region. As a result of the geological background concentration with pre-selection method, background concentrations of selenium and aluminum in groundwater samples were the highest from sedimentary rock as $0.0010mg\;L^{-1}$ and $0.0029mg\;L^{-1}$ and background concentrations of manganese and iron in groundwater samples were the greatest from metamorphic rock as $0.460mg\;L^{-1}$ and $1.574mg\;L^{-1}$, and no chromium background concentration in groundwater samples was found from all geology.

• Research in Community and Public Health Nursing
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• v.11 no.2
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• pp.389-398
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• 2000

The work of visiting nursing personnel consists mostly of direct nursing and it is absolutely necessary that training of the nursing personnel for infection control be emphasized because most of patients are composed of elderly people with chronic diseases and malnutrition who are highly susceptible to infection. Accordingly. this study was designed to provide basic data for the development of an infection control program in public health centers as well as the promotion of perception and performance of infection control by analysing the perception of importance and performance in the infection control of visiting nursing personnel who carry out visiting nursing services. The subjects of this study consisted of a number of visiting nursing personnel working for 15 public health centers. 15 health-center branches. and 16 health clinics. The collection of data was grounded on a questionnaire method. The questionnaire breaks down to 8 questions about general characteristics and 108 questions in connection with the perception and performance of infection control. The results of this study are as follows: 1. 82 subjects (78.1%) responded that it is necessary to control infection. 79 subjects(75.3%) responded that education is necessary for infection control. 50 respondents (47.6%) answered in the affirmative in regard to the role of infection carriers. 2. The mean score for the perception of importance in infection control was 4.55 and that performance accounts for 4.03. this turns out to be very high. 3. In terms of the perception of importance per each field of infection control. medication. the management of contamination and sterilization, the control of environments and instruments. washing hands and individual hygiene as well as the prevention of cross-infection and the supervision of infection stand at 4.72. 4.64. 4.60. 4.58. 4.52 and 4.21 respectively. In terms of performance. the supervision of infection. the control of environments and instruments, individual hygiene and the prevention of cross infection. medication. washing hands, and the management of contamination and sterilization was 4.21. 4.12. 4.10. 4.03. 3.91 and 3.81 respectively. 4. In terms of the correlation between the perception of importance and the performance of infection control. the score stands high in all fields: this means the high perception of importance leads to high performance statistically (P< .05). 5. In terms of the perception of importance in general characteristics. there is no significant difference while the form of working places. working career and the career as visiting nursing personnel show a significant difference in terms of performance(P< .05). From the results. it is suggested that the visiting nursing personnel should be constantly educated with the aid of the development of infection control programs and that instructions and instruments for the management of infection should be worked out so as to enhance the performance of infection control on the part of nurses in applicable communities.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.6
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• pp.749-754
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• 2011

In this study, we propose the design of optimized pRBFNNs-based face recognition system using two-dimensional Image and ASM algorithm. usually the existing 2 dimensional face recognition methods have the effects of the scale change of the image, position variation or the backgrounds of an image. In this paper, the face region information obtained from the detected face region is used for the compensation of these defects. In this paper, we use a CCD camera to obtain a picture frame directly. By using histogram equalization method, we can partially enhance the distorted image influenced by natural as well as artificial illumination. AdaBoost algorithm is used for the detection of face image between face and non-face image area. We can butt up personal profile by extracting the both face contour and shape using ASM(Active Shape Model) and then reduce dimension of image data using PCA. The proposed pRBFNNs consists of three functional modules such as the condition part, the conclusion part, and the inference part. In the condition part of fuzzy rules, input space is partitioned with Fuzzy C-Means clustering. In the conclusion part of rules, the connection weight of RBFNNs is represented as three kinds of polynomials such as constant, linear, and quadratic. The essential design parameters (including learning rate, momentum coefficient and fuzzification coefficient) of the networks are optimized by means of Differential Evolution. The proposed pRBFNNs are applied to real-time face image database and then demonstrated from viewpoint of the output performance and recognition rate.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.134-142
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• 2003

We present an ATM switch architectures based on the multistage interconnection network(MIN) for the efficient multicast traffic control. Many of these applications require multicast connections as well as point-to-point connections. Muiticast connection in which the same message is delivered from a source to arbitrary number of destinations is fundamental in the areas such as teleconferencing, VOD(video on demand), distributed data processing, etc. In designing the multicast ATM switches to support those services, we should consider the fairness(impartiality) and priority control, in addition to the overflow problem, cell processing with large number of copies, and the blocking problem. In particular, the fairness problem which is to distribute the incoming cells to input ports smoothly is occurred when a cell with the large copy number enters upper input port. In this case, the upper input port sends before the lower input port because of the calculating method of running sum, and therefore cell arrived into lower input port Is delayed to next cycle to be sent and transmission delay time becomes longer. In this paper, we propose the cell splitting and group splitting algorithm, and also the fairness scheme on the basis of the nonblocking characteristics for issuing appropriate copy number depending on the number of Input cell in demand. We evaluate the performance of the proposed schemes in terms of the throughput, cell loss rate and cell delay.