• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.435-451
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• 2019

Impossible differential cryptanalysis is an essential cryptanalytic technique and its key point is whether there is an impossible differential path. The main factor of influencing impossible differential cryptanalysis is the length of the rounds of the impossible differential trail because the attack will be more close to the real encryption algorithm with the number becoming longer. We provide the upper bound of the longest impossible differential trails of several important block ciphers. We first analyse the national standard of the Russian Federation in 2015, Kuznyechik, which utilizes the 16-byte LFSR to achieve the linear transformation. We conclude that there is no any 3-round impossible differential trail of the Kuznyechik without the consideration of the specific S-boxes. Then we ascertain the longest impossible differential paths of several other important block ciphers by using the matrix method which can be extended to many other block ciphers. As a result, we show that, unless considering the details of the S-boxes, there is no any more than or equal to 5-round, 7-round and 9-round impossible differential paths for KLEIN, Midori64 and MIBS respectively.

• The Research Journal of the Costume Culture
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• v.8 no.5
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• pp.668-680
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• 2000

The study presents the general types and individual differences of the shape of the adult women's neck and shoulder in our country. It is based on the average value, the standard deviation, the maximum value, the standard deviation, the maximum value, the minimum value and c.v. measured from the women at the age of 19 through 64. The results of this study are as follows ; 1. The factors by factor analysis are five. The first is the size factors of the neck and shoulder. The second is shape factor of neck. The third is plane view and length factor of the neck. The fourth is the side view factor of the neck and shoulder. The fifth is the shape factor of shoulder. Therefore the shape of the neck and shoulder should be examined in the shape factors as well as in the size factors as well as in the size factors for the designing body-suitable clothes. 2. The factors of the concrete objects are the solid view of neck and shoulder, the cross-sectional view of neck line, side view of neck and shoulder and length of neck. The explainable measuring items for the factors are the difference of the length between lower neck round line and the 4㎝ above neck round line, the length of neck, the angle of inclination between fore neck and back neck, the angle of inclination of the side shoulder, the difference of the height between fore neck point and back neck point, the width of shoulder, the width of chest and the width of back. 3. The concrete objects of the neck and shoulder have five types ; Type Ⅰ is average type, Type Ⅱ is thick short neck and the drooping shoulder type, Type Ⅲ I is slender long neck and lean-back shoulder type, Type Ⅳ is thick and rising shoulder type and Type Ⅴ is slender and drooping shoulder type.

• Bulletin of the Society of Naval Architects of Korea
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• v.2 no.1
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• pp.9-14
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• 1965

Ship designers make every efforts to get faster ships in accordance with the development of the Naval Architecture. But for the speed lying over factor length ratio 2.5-3.0, we could put a powerful engine into the conventional round bottom displacement type vessels, but it is very difficult in view point of economy, weight and volume. The principal cause of these speed obstacles is the wave making resistance and researchers are trying to decrease this resistance. One of the resolving ways, planing hulls were applied to small high boats. Planing hull's advantage is not restricted to speed, but the workmanship of the planing hull is easier than those of displacement type vessels of round bottom. Planing hull, therefore, are widely applicable to the intermediate speed boats, which don't have enough high speed to take planing advantage, as well as high speed boats. We will discuss related phenomena of the planing hull in details and this paper we particularly interested in the interjection point(speed length ratio 3.0-3.5 by Mr. D. De Groots) between semi-planing and full planing hulls on the resistance characteristic curve. The paper by Prof. Keuck Chun Kim, "Some Characteristics of Straight Framed V-bottom Hull Forms", Journal of the society of Naval Architects of Korea, Vol.1, No.1, Dec.5, 1964, is referred to the V-bottom hull forms belonging to low speed region and determines practical applicable limit of the speed length ratio combined with construction costs, under which are still used by large commercial vessels. This is the interesting contrast between his and authors. We will further discuss the speed length ratio which is considered as a beginning point to planing effect. For this analysis, we choose 3 model ships: Model (1) and (2) have the same principal dimensions, model 3 varied dimension. Model (1) is full-planing hull, (2) is semi-planing hull and (3) is complete planing hull. They are aimed to collect proper design data for purposed ships.

• Explosives and Blasting
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• v.24 no.2
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• pp.1-8
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• 2006

In this study, a charging density has been differently applied to all holes to improve an excavated length per round on excavating a tunnel in quartzite mine and to prevent a dead pressure phenomena and sintering phenomena. A composition initiating system using simultaneously a direct initiating system and a indirect initiating system with 2 detonators in one hole has been introduced to cut holes. As a bottom part which is difficult to make a free face are charged with a higher charging density and a column part are charged with a lower charging density, the composition charging and initiating system which the power of explosives works effectively in the rock mass is developed. As the results, a dead pressure phenomena and a sintering phenomena being often produced in a hard rock or in a long hole could be prevented. Besides, the workability was improved by about 15% and the specific charge was reduced to about 20%, as an excavated length vs. a drilled length per round could be increased over 95%.

• Journal of IKEEE
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• v.12 no.4
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• pp.246-254
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• 2008

This paper represents a design of a 4 way SIMD processor with multi-thread and dual phase instruction pipeline. 8 threads can be performing in round-robin order, so any hazards can’t occur. The dual phase pipeline makes a pipeline operate as two pipelines, and it can fetch maximum 4 unit instructions at once. This variable length instruction set divide into first phase and second phase instructions, and with this function, complex branch and addressing can be executed at one clock cycle. This processor reduces the code size to quarter, pull out the doubled performance improvement than normal SIMD architecture.

• Journal of Biosystems Engineering
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• v.24 no.4
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• pp.301-308
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• 1999

Path planning for field operation of agricultural machinery is an indispensible part for precision farming or autonomous field operation. In this study, two algorithms (I, II) of generating a time-based shortest operation path were suggested to plan an optimal operation of an agricultural tractor-implement in a rectangular shaped field. The algorithms were based on modification of a minimum spanning tree algorithm, and applied for tractor-implement operations. the generated path was consisted of round operation and returning operation sections. The number of round operation was determined from the condition that a tractor can turn smoothly at headlands. The performance of the algorithms was evaluated by the calculation number for path generation and the total path length generated. Their stability was affected by the number of returning operation, but the algorithm II was considered to be more stable. In addition, the performances of the developed algorithms were compared with those of the conventional field operations at selected field sizes and shapes. The results showed that the algorithms could reduce field operation time greatly. For a 100m$\times$40m field, the reduced path length was 78m. The study also included an user interface program for implementing the algorithms and generating GPS coordinates that could be used in GIS softwares for precision farming.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.11
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• pp.1470-1481
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• 2004

The purpose of this study was to research on facial shape to suggest a quantified data for the domestic apparel and beauty industry. Conducted a measurement research of 278 female college students, We took the photographs of front view and lateral view of the subjects by digital camera and obtained the 69 measurements through the facial measurement program. 264 ,subjects' measurement data were analyzed by various statistical methods such as descriptive analysis, factor analysis and cluster analysis. Using the 69 measurement items,4 factors were selected as key factors for the factor analysis of facial shape, the factors are: \circled1 Front face height \circled2 Side face radial length \circled3 Front face breadth \circled4 Ear height and Gnathion radial length. We categorized the facial shape into four types by cluster analysis. Type 4 is the most common facial shape in female college students: \circled1 Type 1: Round face \circled2 Type 2: Oval face \circled3 Type 3: Square face \circled4 Type 4: Heart shaped face According to the facial shape analysis, facial shape of female college students are consisting of Heart shaped face(34.8%), Round face(29.2%), Square face(23.5%), oval face(12.5%).

• The Research Journal of the Costume Culture
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• v.8 no.1
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• pp.133-144
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• 2000

The purpose of this study was to classify women's face types by visual distinction and to analyze the measurement of face types. A survey was conducted by subjects of 167 women's college students in Kwangju City and Chonnam area. Data were analyzed by Frequencies, Mean, one way ANOVA and Ducan's Multiple Range Test. The major results were as followed ; ·Women's face types were classified by 7 types and there were oblong shape(28.3%), egg shape(25.7%), round shape(23.9%), square shape(12.4%), inverted triangle shape(5.3%), diamond shape(3.5%), triangle shape(0.8%) in the subjects. ·From the measurements of the women's face, index of face length to face breadth was 1.38, it means that the index was different from the other refferences. And the lower face length was longer than the upper and the middle face lengths. ·Differences From those measurements like forehead breadth, face length/bizigion breath(p〈.001), bizigion breadth, bignathion slopper, stature(p〈.01) and trichion breadth, tragion-menton length(p〈.05) were significant in the classified face types.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.96-103
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• 1999

A kinematically admissible velocity field is derived to analyze the forming load and the extruded length in the extrusion/forging process of trochoidally headed bars from round billets. The forming load and the extruded length are obtained by minimizing the total energy-consumption rate. Experiments are carried out with lead billets at room temperature using trochoidally shaped punches. The theoretical predictions of forming load and extruded length are in good agreement with the experimental results.

• 대한공업교육학회지
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• v.32 no.2
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• pp.199-216
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• 2007

Stream Control Transmission Protocol(SCTP) is a transport layer protocol to support the data transmission. SCTP is similar to Transmission Control Protocol(TCP) in a variety of aspects. However, several features of SCTP including multi-homing and multi-streaming incur the performance difference from TCP. This paper highlights the data transfer during the initial slow start phase in SCTP congestion control composed of slow start phase and congestion avoidance phase. In order to compare the mean transfer time between SCTP and TCP, we experiment with different performance parameters including bandwidth, round trip time, and data length. By varying data length, we also measure the corresponding initial window size, which is one of factors affecting the mean transfer time. For the experiment, we have written server and client applications by C language using SCTP socket API and have measured the transfer time by ethereal program. We transferred data between client and server using round-robin method. Analysis of these experimental results from the testbed implementation shows that larger initial window size of SCTP than that of TCP brings the reduction in the mean transfer time of SCTP compared with TCP by 15 % on average during the initial slow start phase.