초록  In this study, the structural analysis of sway brace device for earthquake-proof which can fix a pipe installed in the building was carried out. The sway brace device was analyzed to evaluate not only the deformations of adaptor fitting, support brace member, structure attachment fitting and clamp sway brace fitting that compose it, but also the effective stress of adaptor fitting combined with support brace member by shear bolt. As a result of structural analysis, it can be seen that the deformation of support brace member influences most of the deformation of sway brace device and the design of adaptor fitting must be modified. Above all, it indicates that the sway brace device is suitable for Korea Fire Institute(KFI) approval standard since its total deformation is smaller than the maximum displacement proposed by KFI. The result of this study can be effectively used to investigate the effective stresses and deformations without the performance test of sway brace device according to its setting angle.

NDF (No Defect Found) is a phenomenon in which defects have been found in the manufacturing, operation and use of a product or facility, but phenomenon of defects is not reproduced in the subsequent investigation system or the cause of the defects cannot be identified. Recently, with the development of the fourth industrial revolution, convergence of hardware and software technologies in various fields is spreading to products such as aircraft, home appliances, and mobile devices, and the number of parts is increasing due to functional convergence. The application of such convergence technologies and the increase in the number of parts are major factors that lead to an increase in NDF phenomena. NDF phenomena have a significant negative impact on cost, reliability, and reliability for both manufacturers, service providers and operators. On the other hand, due to the nature of NDF phenomena such as difficult and intermittent cause identification and ambiguity in judgment, it is common to underestimate the cost of NDF or fail to take appropriate countermeasures in corporate management. Therefore, in this paper, we propose a methodology for estimating NDF costs by the PAF model which is a quality cost analysis model and ABC (Activity Based Costing) technique. The methodology of this study suggests a detailed procedure and the concept to accurately estimate the NDF costs, using ABC analysis, accounting system information, and IT system data. In addition case studies have validated the methodology. We think this could be a valid methodology to refer to when estimating the cost of other parts. And, it is meaningful to provide important judgment information in the decision-making process based on quality management and ultimately reduce NDF costs by visualizing them separately by major variable factors.

이 논문은 드럼 세트를 구성하는 악기들 중 스네어 드럼에 사용되는 진동제어장치의 크기와 질량의 변화에 따라 음량과 음색 및 엔벨로프가 어떻게 변화되는지에 대해 연구하였다. 스네어 드럼을 사용하여 연주하는 드럼 연주자 및 음향 엔지니어들에게 진동제어장치의 변화에 따라 도출되는 소리의 특성을 제공하여 표현하고 싶은 스네어 음색을 구사할 수 있는 정보를 제공하는 목적을 가지고 있으며 스네어 드럼의 음색을 구사하는 능력이 향상된다는 것은 음악의 장르와 스타일에 따라 연주자 및 음향 엔지니어의 표현 능력이 향상될 수 있는 긍정적 영향을 끼칠 수 있다. 실험 결과 진동제어장치를 사용하여 면적과 질량의 변화를 준 환경에서 라우드 니스의 변화는 발생하지 않았으며, 주파수 응답의 변화는 미미한 수준이었고, 엔벨로프의 길 이에서는 큰 변화가 발생하였다. 실험과정에서 실제로 듣는 청감상의 스네어 드럼 음색 변화는 매우 크게 나타났으며 특히 질량보다는 면적의 변화에 따른 실험환경에서 큰 음색 변화가 있었다. 결과적으로 진동제어장치는 실질적으로 엔벨로프에만 관여하며, 스네어 드럼은 엔벨 로프의 길이가 짧아 엔벨로프의 앞부분에서 발생하는 음색이 더 중요하다는 일부 인식과 달 리, 엔벨로프의 뒷부분도 인간이 지각하는 음색에 큰 영향을 준다는 연구들이 도출되었다.

With the development of technology, innovations are taking place in the education field, with smart device-based Chinese educational applications drawing attention. This study examines the current status of Chinese educational applications in Korea, China, and the U.S., and explores possible directions to design effective applications for Korean young learners. A total of 179 applications from three countries were investigated and classified based on educational application criteria. Among them, the top five applications were selected from each country using ratings and reviews. Each application was then evaluated and analyzed according to the evaluation criteria. The results demonstrated that applications from the U.S. were the highest scoring overall and highest in terms of content, with applications from China highest in terms of function. The result also presented three common problems, which are limited types of applications, the absence of camera function utilization, and the lack of learning activities to experience Chinese culture. This study recommends further discussions on Chinese educational applications with the broadened scope of application types and target learners.

철근콘크리트 기둥에서 후프철근의 내진갈고리 시공성을 개선하기 위하여 기존 연구에서 “띠철근 갈고리 뽑힘 방지 장치”인 RCC장치(Rebar Confinement Clip)를 제안하여 인발실험을 통한 부착 및 정착성능 실험을 실시하였다. 그러나, 기존 연구의 실험에서는 콘크리트 구조기준에서 제시하는 피복두께를 준수하지 않았다. 그러므로, 보다 신뢰성 있는 실험 결과를 도출하 기 위하여 기준에서 제시하는 피복두께를 준수한 실험체로 실험을 실시할 필요가 있다. 이를 위하여 총 6개 실험체를 제작하여 실험을 실시하였으며 실험결과, 부착 및 정착의 합성강도는 RCC장치로 체결된 띠철근의 갈고리가 내진갈고리가 발휘하는 강도 보다 높게 나타났다. 또한, 내진갈고리의 실험체 균열 진전 및 파괴 양상과 RCC장치로 체결된 띠철근의 실험체는 유사하게 나타났다. 그러므로, 콘크리트 피복두께를 준수한 실험체에서 RCC장치로 띠철근에 체결할 경우 내진갈고리가 발휘하는 동등한 성능을 보유하고 있는 것으로 평가된다.

Recently, with the development of technologies for the fourth industrial revolution, convergence and complex technology are being applied to aircraft, electronic home appliances and mobile devices, and the number of parts used is increasing. Increasing the number of parts and the application of convergence technologies such as HW (hardware) and SW (software) are increasing the No Defect Found (NDF) phenomenon in which the defect is not reproduced or the cause of the defect cannot be identified in the subsequent investigation systems after the discovery of the defect in the product. The NDF phenomenon is a major problem when dealing with complex technical systems, and its consequences may be manifested in decreased safety and dependability and increased life cycle costs. Until now, NDF-related prior studies have been mainly focused on the NDF cost estimation, the cause and impact analysis of NDF in qualitative terms. And there have been no specific methodologies or examples of a working-level perspective to reduce NDF. The purpose of this study is to present a practical methodology for reducing NDF phenomena through data mining methods using quantitative data accumulated in the enterprise. In this study, we performed a cluster analysis using market defects and design-related variables of mobile devices. And then, by analyzing the characteristics of groups with high NDF ratios, we presented improvement directions in terms of design and after service policies. This is significant in solving NDF problems from a practical perspective in the company.

본 연구는 골프참여자들의 골프 디바이스 데이터의 신뢰, 만족 및 인지된 경기력에 대한 관계를 규명하는데 목적이 있다. 연구대상은 일반 골프참여자들을 대상으로 서울, 경기도, 강원도, 경상도, 충청도, 전라도, 제주도 등 7개 시, 도 지역에 온라인 설문을 통해 수집하였으며, 온라인 설문은 총 328부를 수집하여 사용되었다. 수집된 자료는 SPSSWIN 프로그램과 AMOS 를 이용하여 자료를 분석하였으며, 빈도분석, 확인적 요인분석, 신뢰도 분석, 상관관계분석, 구조방정식모형분석 및 경로분석을 실시하였다. 변인 간 관계를 검증한 결과는 다음과 같다. 첫째, 골프참여자들의 골프 디바이스 데이터의 신뢰는 만족에 정( + )에 유의한 영향을 미쳤다. 둘째, 골프참여자들의 골프 디바이스 데이터의 신뢰는 인지된 경기력에 영향을 미치지 않았다. 셋째, 골프참여자들의 골프 디바이스 데이터 만족은 인지된 경기력에 영향을 미치지 않았다. 결론적으로 골프참여자들이 골프 디바이스를 통해 제시된 데이터를 신뢰하고 만족한 결과를 얻고 있다는 것을 알 수 있었다. 하지만 인지된 경기력에는 영향을 미치지 못했다는 점에서 골프참여자들은 골프 디바이스를 경기력을 높여준다는 생각보다는 골프를 하기 위해서 당연히 사용해야 되는 것으로 생각할 수 있다.

Dynamic behavior of piezoelectric ZnO nanowires is investigated using finite element analyses (FEA) on FE models constructed based on previous experimental observations in which nanowires having aspect ratios of 1:2. 1:31, and 1:57 are obtained during a hydrothermal process. Modal analyses predict that nanowires will vibrate in lateral bending, uniaxial elongation/contraction, and twisting (torsion), respectively, for the three ratios. The natural frequency for each vibration mode varies depending on the aspect ratio, while the frequencies are in a range of 7.233 MHz to 3.393 GHz. Subsequent transient response analysis predicts that the nanowires will behave quasi-statically within the load frequency range below 10 MHz, implying that the ZnO nanowires have application potentials as structural members of electromechanical systems including nano piezoelectric generators and piezoelectric dynamic strain sensors. When an electric pulse signal is simulated, it is predicted that the nanowires will deform in accordance with the electric signal. Once the electric signal is removed, the nanowires exhibit a specific resonance-like vibration, with the frequency synchronized to the signal frequency. These predictions indicate that the nanowires have additional application potential as piezoelectric actuators and resonators.

PURPOSES : The purpose of this study is to propose the certification process of International Roughness Index measuring device, i.e., a method for evaluating riding quality on road surfaces. METHODS : ROMDAS was selected as a reference device for verifying the accuracy of the IRI measuring device and the reliability of ROMDAS was checked through leveling in the laboratory and outdoors. To verify four different IRI measuring devices in Korea, the proper field test section was selected and IRI evaluation was conducted. A distance measuring instrument (DMI) - for verifying the accuracy of mileage - and IRI (as an index of roughness) were selected as the main evaluation parameters. For DMI verification, five repeated experiments were conducted for a 1 km section and, for IRI verification, speed variables of 40 km/h, 60 km/h, and 80 km/h were selected. Each device was tested at each speed 10 times. The accuracy of the measurement device was analyzed by comparing the measurement results with the verification criteria. RESULTS : As a result of the comparative experiment between the leveling and ROMDAS devices, the deviation of each measurement point value was within 1 mm and the R2 value was 0.8, demonstrating an excellent correlation. As a result of DMI verification, the tolerance of the three devices was found to be within 0.1 %; however, one device had a tolerance of 0.8 %, indicating that correction was necessary. For IRI evaluation, the average IRI value of the two reference devices was 2.02 m/km and the Minnesota standard was used as an analysis criterion. After the test, only one of the four devices was found to be effective across all speed ranges. Therefore, it was determined that additional sensor calibration is required to improve accuracy. CONCLUSIONS : In this study, the IRI device accuracy was evaluated through field tests. Hence, a new certification process for the IRI test device was proposed via four steps. To improve the accuracy of the IRI measurement, it is necessary to periodically verify the device. If this proposed certification process is applied, the accuracy of the IRI devices can be improved.

This paper proposes a methodology for gantry route optimization in order to maximize the productivity of a odd-type surface mount device (SMD). A odd-type SMD is a machine that uses a gantry to mount electronic components on the placement point of a printed circuit board (PCB). The gantry needs a nozzle to move its electronic components. There is a suitability between the nozzle and the electronic component, and the mounting speed varies depending on the suitability. When it is difficult for the nozzle to adsorb electronic components, nozzle exchange is performed, and nozzle exchange takes a certain amount of time. The gantry route optimization problem is divided into the mounting order on PCB and the allocation of nozzles and electronic components to the gantry. Nozzle and electronic component allocation minimized the time incurred by nozzle exchange and nozzle-to-electronic component compatibility by using an mixed integer programming method. Sequence of mounting points on PCB minimizes travel time by using the branch-and-price method. Experimental data was made by randomly picking the location of the mounting point on a PCB of 800mm in width and 800mm in length. The number of mounting points is divided into 25, 50, 75, and 100, and experiments are conducted according to the number of types of electronic components, number of nozzle types, and suitability between nozzles and electronic components, respectively. Because the experimental data are random, the calculation time is not constant, but it is confirmed that the gantry route is found within a reasonable time.

목적 : 본 연구는 복지용구 사용자의 보호자들을 대상으로 현상학적 연구방법을 실시하여 복지용구 품목 및 서비스에 대한 개선방안을 제시하고자 한다. 연구방법 : 복지용구를 2년 이상 사용하고 있는 사용자의 보호자들 5명을 대상으로, 반 구조화된 전화인터 뷰를 실시하였다. 전화 인터뷰는 2회 실시되었고 인터뷰 후 추가적인 질문이나 내용확인은 전화 통화나 이메일로 하였다. 인터뷰 한 모든 내용은 전사한 후 Giorgi의 현상학적 연구방법론에 따라 분석되었다. 결과 : 인터뷰 내용은 18개의 의미단위, 9개의 하위구성요소 그리고 구성요소 5개로 정리하였다. 복지용구 사용자의 보호자들은 복지용구 품목에 대한 개선점으로 사용자 질환 및 특성을 고려한 복지용구, 다양 한 옵션기능이 내제된 복지용구, 고령친화용품 기반의 복지용구 그리고 보호자의 부담을 덜 수 있는 복 지용구에 대한 필요성을 제시하였다. 복지용구와 관련된 서비스에서는 복지용구의 선택과 사용방법에 대 한 훈련을 담당하는 전문가 복지용구 전문가와 복지용구 사용에 대한 지속적인 사후관리의 필요성을 언 급하였다. 결론 : 본 연구는 복지용구의 사용과 전달과정에 영향을 미칠 수 있는 보호자의 견해를 살펴 복지용구와 관련한 개선방안을 사회적 환경의 시선에서 제시했다는 점에서 의의가 있다. 본 연구 결과가 추후 재가 복지서비스 제도개선에 기초자료로 활용되기를 기대한다. 추후에는 본 연구결과를 기반으로 사용자 및 보호자들의 요구도를 바탕으로 한 복지용구의 품목 개발이 필요할 것이다.

When an unexpected excessive seismic load is applied to the base isolation of arch structure, the seismic displacement of the base isolation may be very large beyond the limit displacement of base isolation. These excessive displacement of the base isolation causes a large displacement in the upper structure and large displacement of upper structure causes structural damage. Therefore, in order to limit the seismic displacement response of the base isolation, it is necessary to install an additional device such as an anti-uplift device to the base isolation. In this study, the installation direction of the base isolation and the control performance of the base isolation installed anti-uplift device were investigated. The installation direction of the base isolation of the arch structure is determined by considering the horizontal and vertical reaction forces of the arch structure. In addition, the separation distance of the anti-uplift device is determined in consideration of the design displacement of the base isolation and the displacement of the arch structure.