• Journal of Communications and Networks
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• v.11 no.5
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• pp.455-463
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• 2009

We consider the challenges of finding good puncturing patterns for rate-compatible low-density parity-check code (LDPC) codes over additive white Gaussian noise (AWGN) channels. Puncturing is a scheme to obtain a series of higher rate codes from a lower rate mother code. It is widely used in channel coding but it causes performance is lost compared to non-punctured LDPC codes at the same rate. Previous work, considered the role of survived check nodes in puncturing patterns. Limitations, such as single survived check node assumption and simulation-based verification, were examined. This paper analyzes the performance according to the role of multiple survived check nodes and multiple dead check nodes. Based on these analyses, we propose new algorithm to find a good puncturing pattern for LDPC codes over AWGN channels.

• Journal of KSNVE
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• v.4 no.2
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• pp.221-230
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• 1994

This paper deals with the dynamic stability and the nonlinear behavior of a check valve system. The nonlinear equations of motion of fluid-valve interation model are derived, which are composed of the unsteady Bernoulli's equation included the jet flow mechanism and equation of motion of a check valve formulated by one degree of freedom. Also, the derived equations of motion are nondimensionalized. According to the change of the nondimensional parameters, the stabilities of the system are analyzed, and the nonlinear interaction responses of the check valve and the passing flow rate are obtained. As the results, the stability charts are constructed for the variation of nondimensional parameters. It is shown that self-excited vibrations exist in a check valve system. And also the Hopf bifurcation and the periodic doubling are found. The presented theoretical model of a check valve system can be utilized to the design and operation of a piping system with the check valve.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.49-55
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• 2014

This paper examines the effects of spring characteristics and stiffness in relation to the characteristics of hydrodynamic force. Spring forces and stiffness determine the performance of this type of pan check valve and have an effect on the overall operation. The hydraulic efficiency of the pan check valve is relatively low compared to that of a common check valve. However, a pan check valve is structurally more stable than a common check valve. We implemented the optimum design to increase the flow rate and to resolve the suppression of the pressure drop according to the extent of the compression of the spring. From the results of a flow analysis, we demonstrate spring stiffness design criteria depending on the extent of the compression of the spring of pan check valve acting on the fluid at the inlet 1 MPa pressure.

• The KSFM Journal of Fluid Machinery
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• v.8 no.6 s.33
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• pp.15-25
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• 2005

Check valves playa vital role in the operation and protection of nuclear power plants. Check valves failure in nuclear power plants often lead to a plant transient or trip. The analysis of historical failure data gives information on the populations of various types of check valves, the systems they are installed in, failure modes, effects, methods of detection, and the mechanisms of the failures. A majority of check valve failures are caused by improper application. The experimental apparatus is designed and installed to measure the disc positions with flow velocity, Vopen and Vmin for 3 inch and 6 inch swing check valves. The minimum flow velocity necessary to just open the disc at a full open position is referred to as Vopen, and Vmin is defined as the minimum velocity to fully open the disc and hold it without motion. In the experiments, Vmin is determined as the minimum flow velocity at which the back stop load begins to increase after the disc is fully opened or the oscillation level of disc is reduced below $1^{\circ}$. The results show that the Vmin velocities for 3 inch and 6 inch swing check valves are about 27.3% and 17.5% higher than the Vopen velocities, respectively.

• Journal of Communications and Networks
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• v.15 no.1
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• pp.71-76
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• 2013

A new class of quantum low-density parity-check (LDPC) codes whose parity-check matrices are dual-containing matrices constructed based on lines of Euclidean geometries (EGs) is presented. The parity-check matrices of our quantum codes contain one and only one 4-cycle in every two rows and have better distance properties. However, the classical parity-check matrix constructed from EGs does not satisfy the condition of dual-containing. In some parameter conditions, parts of the rows in the matrix maybe have not any nonzero element in common. Notably, we propose four families of fascinating structure according to changes in all the parameters, and the parity-check matrices are adopted to satisfy the requirement of dual-containing. Series of matrix properties are proved. Construction methods of the parity-check matrices with dual-containing property are given. The simulation results show that the quantum LDPC codes constructed by this method perform very well over the depolarizing channel when decoded with iterative decoding based on the sum-product algorithm. Also, the quantum codes constructed in this paper outperform other quantum codes based on EGs.

• The Research Journal of the Costume Culture
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• v.17 no.5
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• pp.746-757
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• 2009

This study is focused on the elucidation of efficient and correct marking methods by comparing and analyzing marker efficiency depending on the marking job condition such as interval of checking-pattern, width of materials, and marker orientation using man's shirts. To compare the marking efficiency of shirts, plain and check-patterned materials with the intervals of $1.5{\times}1.5cm$, $3{\times}3cm$, and $5{\times}5cm$ were selected. First, in the comparison of marking efficiency depending on materials width, the highest efficiency was obtained with nap-either-way position of 150cm, plain materials and lowest efficiency with nap-one-way position of 150cm, $5{\times}5cm$ check-pattern materials. Regardless of the direction of marker position, the marking efficiency of 150cm width was higher than 110cm width in the plain, $1.5{\times}1.5cm$ and $3{\times}3cm$ check-pattern interval, but the marking efficiency of 110cm width was higher than 150cm width in the $1.5{\times}1.5cm$ check-pattern interval. Second, in the comparison of marking efficiency depending on the direction of marker position, regardless of check-pattern interval and material width, the highest efficiency was obtained with nap-either-way position. And nap-up-and-down and nap-one-way follows next. Third, in the comparison of marking efficiency depending on check-pattern interval, the efficiency of plain materials was higher than those of check-patterned materials. And increasing the intervals decreased marking efficiency and vice versa. So the lowest efficiency was obtained with $5{\times}5cm$ check patterned materials.

• Korean Journal of Digital Imaging in Medicine
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• v.3 no.1
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• pp.126-132
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• 1997

Purpose : To apply to Program of Auto processor quality control after comparison of Film density variations with amendments to Auto density by using Check density program and Adjust density program of calibration mode into the Laser imager. Methods : Observe Check and Adjust density variations on the Control chart with standard step and value during seven months from December, 1995 to June, 1956 extending twice a week. (1) Measure density value on the steps after printing out 17-step sensitometric pattern of the Check density program. (2) In the same way, measure density values after amending density by using Adjust density program If they are exceeding allowable error limit. Results : In case of Check density program, the exceeding limit rates of Density difference(DD) and Middle density(MD) are: FL-IM3543 DD=75%. MD=72.5%, FL-IMD DD=0%. MD=30.8%(14.5%) After amending density by using Adjust density program, the exceeding limit rates of all both Laser imager were zero percent. The standard deviations are show lower FL-IM D than FL-IM3543 on the Check density control chart, but higher on the Adjust density control chart. Conclusion : (1) Check density variations by printingout sensitometric pattern extending once a week at least for quality control of the Laser imager. (2) In case of a dusty place, check the Laser beam transmission after cleaning Laser optical unit extending once a month. (3) Be sure to measure and check density values by using adjust density program if they are exceeding allowable error limit. (4) Maintain much better film density by performing the adjust density program even if check density values are existed within normal limit.

• Journal of the Korean Society of Costume
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• v.52 no.2
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• pp.31-44
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• 2002

This study was intended to inquire into Check Pattern. The purpose of this study attempted to make a systematic investigation of the characteristic of the Check Pattern, the checker using vertical and horizontal lines which was the universal plastic element and inquire into it in terms of era, designers and combined work. By doing so, this study attempted to Investigate the phase of the Check Pattern in world fashion and further forecast the future of checker design applicable to the 21th century fashion. The result can be summarized as follows : 1. Mondrim's neo-plasticism has not only had a great influence on Op Art and Minimalism work but is deeply related to fashion and textile design. Mondrian used vertical and horizontal line ad the dualistic element. 2. The checker is estimated to have been used since the Etruian times, though uncertain. and largely divided into the Madras check and Scotland Check. Though the origin of the tartan representation of the Scotland check can not be accurately found out, it began to emerge in around the 13th century. 3. Check Pattern has began to be widely used with the development of the textile industry since 1826 and been used in every typical Sihoutto appearing in each era up to the present. And Check Pattern is used most designer in the world, who represent their own personality in their works. This study could find out that the checker is the element of Infinite applicability in the future. It is expected that the sophisticated and beautiful design using the chocker will be presented by many korean designer though the overall and systematic study of the checker.

• The Journal of Industrial Distribution & Business
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• v.12 no.1
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• pp.15-30
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• 2021

Purpose: Year of 2020, COVID-19 has been changing the people's everyday life to ways never been thought of before all over the world. The IT and electronic industry, the methods of supplying goods and services have been changed from contact to un-tact environments based on un-tact systems very rapidly. COVID-19 has been striking the tourism and the travel industry, especially the airline and hotel industry of which services are provided by human. For the passenger service of airliner, automation has been propelled and un-tact style of service has become mainstreams except cabin service since 2000's. For passenger transportation, due to traffic regulations and exclusions etc., switching to new ways is not easy. However, under the new environment made by COVID-19, kiosk check-in, web check-in and mobile check-in has become more important. In this study, the characteristics of airline customers using mobile goods are investigated to find ways to raise the rate of utilizing mobile check-in and to increase the efficiency of boarding process. Research design, data, and methodology: Considering the COVID-19 environment, survey was done by online research company. The research model is designed to integrate the user characteristics and usage/purchase motive and technology acceptance theory. Especially considering infectious diseases prevention, concern of safety is adopted as one of the usage motive variable. Results: Extraversion or conscientiousness characteristics prefers counter check-in(contact service), while openness characteristics prefers mobile check-in(un-tact service). Concern of safety for infectious disease shows strong non-preference on counter check-in. Conclusions: Regarding service type regardless of type of the industry, automation and un-tact have been mainstreams due to high costs of labor, efficiency and standardization issue, etc., and COVID-19 has given impetus to them. For airliner, un-tact service including boarding process service has been more and more important. To raise the rate of un-tact service use, the characteristics of the user should be analyzed first. The study results indicate that for extraversion or conscientiousness, some kinds of methods to induce them to use un-tact service more are needed.

• Parasites, Hosts and Diseases
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• v.61 no.1
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• pp.53-59
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• 2023

Head louse infestation is a significant public health problem across the world, particularly among preschool and primary schoolchildren. This study investigated the trends of head louse infestation in the Republic of Korea over a 9-year period (2011-2019), targeting primary schoolchildren in 3 areas of Seoul, 4 other large cities, and 9 provinces. A survey was administered annually by the health staff of each regional office (n= 16) of the Korea Association of Health Promotion (KAHP). The branch offices of KAHP examined a total of 51,508 primary schoolchildren, comprising 26,532 boys and 24,976 girls. Over the 9-year survey, a total of 1,107 (2.1%) schoolchildren tested positive for adults and/or nits of Pediculus humanus capitis. The prevalence was 2.8% (133/4,727) in 2011-2012 and gradually decreased to 0.8% (49/6,461) in 2019 (P< 0.05). Head lice were found more frequently in girls (3.0%; 746/24,976) than in boys (1.4%; 361/26,532) (P< 0.05). In terms of geographic localities, the highest infestation rate, 4.7% (average prevalence over 9 years), was observed in southern Seoul (Gangnam branch of KAHP), whereas the lowest infestation rate, 0.7%, was seen in Gyeongsang (north and south provinces) and western Seoul. Although the prevalence decreased significantly during the 9-year period, head louse infestation remains a health and hygiene issue among primary schoolchildren in the Republic of Korea. Regular surveys along with health education are needed to further improve children's hair hygiene.