• Journal of the Korean Institute of Navigation
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• v.9 no.1
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• pp.41-81
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• 1985

Tidal phenomenon can be utilized by the wise and cautious mariner to safely perform his duties as pilot and navigator. It can be either a help or hindrance to the mariner. The principle of MULDAE which expresses the determination of the state of the tide based upon knowledge of the lunar date and it has been used in Korea since ancient times. The folk method of calculation was essentially based on an unsystematic division of the lunar month, traditionally using the numbers 7 or 8. As the lunar cycle is complete in 15 days the tidal cycle should also correspondence closely to the lunar date. This paper represents the first scientific attempt to systematically investigate this unique traditional method of tidal calculation and contains a comparison of the MULDAE and ordinary (solar based) tide calculation methods. MULDAE was compared with the standard tide table for standard and island ports in Korea from 1982 to 1985. This study concluded that MULDAE was indeed an accurate adn reliable predictor of tidal activity. Furthermore, the number 6 was found to be the correct divisor upon which to base MULDAE calculations Also a formula expressing MULDAE as a function was discovered. This research show that MULDAE can be applied nationwide and is a reliable and easy way to predict tides based upon mean figures for certain ports and island A calender showing MULDAE is presented here for the first time. A clear relationship between the MULDAE method of calculating tides and the use of ordinary tide tables is proven.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.108-111
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• 2008

In this paper, we propose an advanced hardware architecture for the CAVLC entropy encoder engine for real time Full HD video compression. Since there are 384 data coefficients which are sum of 376 AC coefficient and 8 DC coefficient per one macroblock, 384 coefficient have to be processed per one macroblock in worst case for real time processing. We propose an novel architecture which includes parallel architecture and pipeline processing, and reduction "0" in AC/DC coefficient table. To verify the proposed architecture, we develop the reference C for CAVLC and verified the designed circuit with the test vector from reference C code.

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.514-520
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• 1993

In this paper the cure cycle of carbon fiber/phenolic resin was investigated by the Taguchi Method in an experimental design. Experiments were systematically performed using $L_{18}(2^1 \times 3_7)$ orthorgonal array table of the experimental design. In the experimental design, eight compression molding parameters (heating rate, pressing temperature, pressing rate, molding pressure, curing temperature, dwell time at curing temperature, cooling rate and degassing) were considered and the effects of the parameters on the flexural strength and the apparent porosity of carbon fiber/phenolic composites were investigated. The analysis of variance for the experimental results indicated that molding pressure and curing temperature are the most significant parmeters in the flexural strength and the apparent porosity of carbon fiber/phenolic resin composites, respectively.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.4
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• pp.65-74
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• 2018

The primary objective of this study is to develop a conceptual design of automated pothole patching machine that improves the conventional work in safety, quality, and productivity. For this, the following research works are conducted sequentially; 1)literature review, 2)selection of element technology for conceptual design, 3)deduction of work process and conceptual design, 4)life cycle cost analysis of the conceptual design. As a result, X-Y table telescopic manipulator, pothole patching end effector, realtime pothole recognizer, 3D pothole volume profiler, automated pothole patching machine controller are selected as core technologies. Furthermore, a conceptual design and working process of an automated pothole patching machine are developed based on the core technologies. According to the life cycle cost analysis result, the cost of the automated method was 38.3% less than that of the conventional method, and the economic efficiency was also superior(ROR 77.1%, Break-even Point 23.8month). It is expected that the application range and impact on the construction industry will be enormous due to the increasing trend of road maintenance market.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.1
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• pp.1-9
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• 2022

Fixslicing AES is a technique that omits the Shiftrows step to minimize the cost of the linear layer of Bitsliced AES, showing a 30% performance over the Bitsliced technique. However, the amount of code increases to compensate for the omitted shiftrows. Therefore, it is proposed to be divided into Semi-Fixsliced in which only half of shiftrows are omitted and Fully-Fixsliced in which Shiftrows are omitted completely. In this paper, we propose a CTR mode implementation of Fixslicing AES on RISC-V using the pre-computed table technique. By utilizing the characteristics of the CTR mode, it is possible to perform fast encryption by omitting up to the second round SubBytes from the encryption process through pre-computed up to the second round SubBytes operation. Using this technique, it was confirmed that Semi-Fixsliced has a performance of 1,345 cycles per block and a performance improvement of 7% compared to the previous performance result, and Fully-Fixsliced has a performance of 1,283 cycles per block and a performance of 9% compared to the previous performance result on 32-bit RISC-V.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.247-255
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• 2011

Currently, there is database for per unit requirements of major construction materials in terms of energy consumption and $CO_2$ emission based on the input-output table published by the Bank of Korea in 2000, but no database for per unit requirements based on input-output tables was published in 2005 and 2007. The purpose of this study was to calculate the unit requirement values of major construction materials in terms of energy consumption and $CO_2$ emission generated by using the input-output tables published in 2005 and 2007. To estimate the unit requirement values, a database building method with the input-output tables was adopted by selecting 16 types of construction materials in wide use on construction sites. When the study results were compared with existing unit requirement values based on the input-output table of 2000, there were small discrepancies, from which it can be interpreted that the method used in the study is reasonable. Unit requirement values estimated based on input-output tables of 2005 and 2007 tended to decrease, and the highest value of energy consumption and $CO_2$ emission were found in the materials using cement and rebar.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.34-47
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• 2000

Since carbon fiber epoxy composite materials have excellent properties for structures due to their high specific strength, high specific modulus, high damping and low thermal expansion, the hollow shafts made of carbon fiber epoxy composites have been widely used for power transmission shafts for motor vehicles , spindles of machine tools, motor base, bearing mount for tool up and manufacturing. The molded composite machine elements are not usually accurate enough for mechanical machine elements, which require turning drilling , cutting and grinding. The experiment are surface grinding wheel GC60 to the carbon fiber epoxy composite specimen with respect to staking angle [0]nT , [45]nT, [90]nT on the CNC grinding machine. In this paper, the surface grinding characteristics of composite plate, which are surveyed experimentally and analytically with respect to the grinding force, surface roughness and wheel loading according to the variable depth of cut, wheel velocity and table feed rate are investigated.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.106-112
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• 2000

The purpose of this paper is to study on the control of the engine idle speed under sudden A/C load which is one of the most severe disturbances on engines. Three types of the closed-loop controller are developed for the stable engine idle speed control. The input of the controller is an error of rpm. The output of the controller is an ISCV duty cycle. The anticipation delay is considered to deal with the delay time of the air mass in engine. The PID, Fuzzy and PID-type Fuzzy controllers with the anticipation delay have improved the engine idle speed condition more than current ECU map table under the A/C load.

• Corrosion Science and Technology
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• v.9 no.2
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• pp.67-73
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• 2010

Niobium microalloying is effective in hot-rolled and cold-rolled steels by providing a fine-grained microstructure resulting in increased strength. To optimize the strengthening effect, alloy design and hot-rolling conditions have to be adapted. As a key issue the dissolution and precipitation characteristics of Nb are discussed in particular with regard to the run-out table conditions. It is then considered how the hot-rolled microstructure and the solute state of Nb interact with the hot-dip galvanizing cycle. The adjusted conditions allow controlling the morphology and distribution of phases in the cold-rolled annealed material. Additional precipitation hardening can be achieved as well. The derived options can be readily applied to produce conventional HSLA and IF high strength steels as well as to modern multiphase steels. It will be explained how important application properties such as strength, elongation, bendability, weldability and delayed cracking resistance can be influenced in a controlled and favorable way. Examples of practical relevance and experience are given.

• Journal of the Korean Home Economics Association
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• v.49 no.2
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• pp.51-62
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• 2011

The purpose of this study was to develop field programs to activate family volunteering and thereby promote healthy family life. The programs were based on a review of family ecological theories of family volunteering activities. A focus group interview was conducted about satisfaction of the program with five volunteers who were experiencing the same family life cycle. The results of study showed that growing sprouts, which are environmentally friendly activities in family, and family volunteer activities lead to family leisure, table, community sharing cultures and cooperation culture between the family and the community. These effects can ultimately contribute to the creation of a healthy family culture.