• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.814-821
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• 2005

When there are many tags using the same frequency around the reader in RFID system, they disturb each other and in the end their response cannot be received by the reader. To solve this disturbance and fast identify the tags, the anti-collision algorithm, which is the core technology in RFID system, is needed. We propose two ALOHA-type Dynamic Framed Slotted ALOHA(DFS-ALOHA) algorithms using Dynamic Slot Allocation(DSA), which dynamically allocates the frame size in accordance with the number of tags and Tag Estimation Method(TEM), which estimates the number of tags around the reader. We also compare the performance of the proposed DFS-ALOHA algorithms with that of the conventional Framed Slotted ALOHA (FS-ALOHA) algorithms and the algorithms proposed by Vogt using OPNET simulation. According to the analysis, the two proposed DFS-ALOHA algorithms(DFS-ALOHA I and DFS-ALOHA II) show better performance than the conventional ALOHA-based algorithms regardless of the number of tags. Although the two proposed DFS-ALOHA algorithms show the similar performance, BFS-ALOHA ll is better because it is easier to be implemented in the system and the complexity is lower.

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.351-359
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• 2019

Recognizing that the fundamental cause of construction safety accidents was a lack of safety management activities in the planning and design phases, the government made the Design for Safety (DFS) system mandatory in May 2016. However, awareness among ordering parties and designers regarding this system is significantly low, and the system has not been properly established due to reasons such as the need for additional work and a lack of professional manpower. In this study, the awareness of ordering parties and designers of the DFS system was analyzed through a survey, various problems in DFS work execution were identified and measures for improvement were presented. Measures to improve the efficiency in DFS work execution involve the discovery of risk factors and establishment of countermeasures, and here the establishment of a DFS work support system that enables the sharing of information between institutions is the most urgent priority. In addition, it is also urgently necessary to establish a dedicated organization in charge of DFS work, cultivate professional manpower, develop the relevant education programs and establish a proper cost calculation standard for DFS work execution by design offices.

• Korean Journal of Construction Engineering and Management
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• v.20 no.5
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• pp.95-103
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• 2019

While the Design for Safety (DFS) system has been introduced to Korea, the ordering parties and designers who are implementing this system still have a very low awareness of it. Most ordering parties and designers have a negative view of this system due to a variety of reasons, including the additional workload and their lack of professional manpower. The purpose of this study is to suggest measures to improve the DFS work performance by standardizing the DFS work process and analyzing the level of work performance in each business carried out by ordering parties and designers in order to ensure the efficient execution of DFS business. In conclusion, to improve the DFS work performance of ordering parties and designers, the development of a business support system is suggested, which supports key works such as the identification of risk factors, the provision of measures to reduce such factors, and risk assessment, and provides relevant information to allow ordering parties and designers to prepare the DFS report smoothly.

• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.101-112
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• 2009

Recently, with the existing speed-management by law enforcements and physical speed-reduction facilities, the country newly adopted Driver Feedback Sign (DFS) system, which displays driving speed in order to guide the driver to an advisable driving condition. DFS is mainly used in school zones due to reasons related to the ITS. Accordingly, because it is predictable that DFS will result in speed-reduction without legal forces and would have an effect on physical speed-reduction facilities, intersection, crosswalks, and road-alignments, this study will try to verify the efficiency of DFS by researching the vehicle speed in national highways and school zones, which have similar conditions to the urban arterial road. In consequence, on national highways, the drivers had a tendency to travel according to the road-environment such as urban arterial road and not reduce speed voluntarily. In school zones, drivers tend to reduce speed in mornings and afternoons when children travel to school or home, showing that the resulting effect is different according to the road-environment where DFS is installed, and the time slot of the DFS.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.31-38
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• 2008

Under the recent situation that there increase the efforts to facilitate DFS(driver feedback sign) in school zones and children's protection areas caused by severity of traffic impact on children, the current study aims at predictively evaluating how and to what extent the reduced car speed is influential to the reduction of traffic accidents in elementary schools located in Buchon city by analyzing the velocity variation before and after DFS installation including its reduction ratio in traffic accidents as well as related literature survey. It, furthermore, aims at identifying applicable effectiveness in DFS operation for elementary schoolers in Buchon based on the data collected.

• Journal of the Korean Society of Safety
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• v.34 no.6
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• pp.38-49
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• 2019

While the overall industrial accident rate has been decreased, but those of the construction industry has not been. For safety management during the planning/design phase, which accounts for 45% of the cause of accident at the construction site, Design For Safety (DFS) was established to minimize a hazard and risk in 2016. Currently, DFS system has difficulty settling down in Korea due to the several reasons. So, this paper aims to propose to the Key Success Factor (KSF) and related action plan to improve DFS system. This study was conducted by following 2 steps: i) identification of problems on current DFS, and ii) proposal of KSF and following action plan for DFS. The DFS in Korea was compared with UK, Singapore, Australia, and US on 7 criteria (application target, execution period, change of design, collaboration among participants, expert participants, alternative review and decision support system). DFS was compared with other countries's system based on the identical criteria and the corresponding improvement measures were also proposed. The results of this study can be utilized to improve DFS system in various aspects.

• Atmosphere
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• v.33 no.4
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• pp.387-398
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• 2023

The double Fourier series (DFS) spectral dynamical core is evaluated for the two idealized test cases in comparison with the spherical harmonics (SPH) spectral dynamical core. A new approach in calculating the meridional expansion coefficients of DFS, which was recently developed to alleviate a computational error but only applied to the 2D spherical shallow water equation, is also tested. In the 3D deformational tracer transport test, the difference is not conspicuous between SPH and DFS simulations, with a slight outperformance of the new DFS approach in terms of undershooting problem. In the baroclinic wave development test, the DFS-simulated wave pattern is quantitatively similar to the SPH-simulated one at high resolutions, but with a substantially lower computational cost. The new DFS approach does not offer a salient advantage compared to the original DFS while computation cost slightly increases. This result suggests that the current DFS spectral method can be a practical and alternative dynamical core for high-resolution global modeling.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2000.05a
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• pp.260-277
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• 2000

최근 미국의 모토롤라(주)에서 시작된 6 시그마(Six Sigma) 경영이 우리나라의 기업들에게 큰 관심의 대상이 되고 있다. 이 논문은 6 시그마 중에서 설계 및 개발분야에 사용되는 6$\sigma$ 설계(Design for Six Sigma: DFSS)에 관하여 고찰하여 보는 논문이다. 6 시그마에 관한 많은 이론이 나와 있으나 아직 DFSS에 관해서는 매우 미약한 편이다. 이 논문에서는 먼저 DFSS의 정의, DFSS 프로세스의 단계, DFSS의 로드맵 등을 먼저 다루고, 다음으로 DFSS에서 사용되는 각종의 과학적 관리기법들(품질기능전개, Scorecard, FMEA, TRIZ, 다구찌설계 등)에 대하여 간단히 기술하기로 한다. 마지막으로 DFSS의 실무적용방법을 제안한다.

• KIEAE Journal
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• v.6 no.2
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• pp.43-50
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• 2006

A Double Facade System(DFS) is well known as an innovative solution of ecological facade in the west european countries. There are more than 200 various realized DFS in Germany. At the same time, the korean engineers have researched to find out the physical advantages of DFS in the moderate korean climate, which has a very humid summer with high temperature and a dry winter with low temperature. For example, the monthly mean temperature in Korea comes up to 28K, while that in Germany comes up to only 19K. That is, why a other solution of DFS is needed in Korea. This study has experimented the physical performance of the natural ventilation in the heating period. The preheating function of the cold air by DFS can improve no doubt the performance of the natural ventilation at the cold season as well as spring and autumn. The physical difference between single and double facade on natural ventilation has been tested at the newly constructed laboratory, which can turn $360^{\circ}$ to confirm the characteristic of a facade with the various directions. The results show the natural ventilation of the DFS has definitely much more comfortable than that of the single facade system. The air velocity of the inflow as well as the air temperature in the DFS provide a more stable condition than in the SFS. The theoretical limit(air velocity max 0.2m/s, air temperature min. $18^{\circ}C$, temperature difference between 100mm and 1700mm height max. 3K) on the indoor comfortableness doesn't go over in the DFS. On the other hand, the SFS showed an unstable condition with an excess of comfortableness limit on air velocity as well as temperature. In view of the researching results so far achieved, the research came to a conclusion, that the DFS can provide a more comfortable indoor condition by the preheating in the heating period than a SFS, and the period of natural ventilation in winter time could be definitely increased at the DFS.

• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.2
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• pp.85-92
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• 2015

Background: Many people experience varying levels of discomfort when confronted with the prospect of dental treatment. Dental treatment can be a traumatic experience, especially for children and adolescents with dental anxiety. In this age group, dental fear causes a significant problem in dental management and has been related to severe dental caries and dental pain. The Dental Fear Survey (DFS) is the most widely used measure of dental fear. This study was undertaken to develop the Korean version of the DFS (K-DFS) and test its reliability and validity. Methods: The K-DFS, which uses projective techniques to measure children's and adolescents' dental fear, was developed. The DFS was translated into Korean and participants were selected via convenience sampling. Reliability and validity were tested using data from a sample of 813 middle school students in Gyeonggi Province, selected from the Self questionnaire survey. The K-DFS was administered twice to 102 adolescents aged 12-15 years. Results: The K-DFS had high internal consistency reliability (99.1%) but low test-retest reliability. Conclusions: The results indicate that the Korean versions of the DFS have good internal consistency reliabilities and test-retest validities. However, we need to further examine the test-retest reliability of the K-DFS and replicate the current study in different samples covering various age groups.