• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.143-146
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• 2007

Due to the expansion of cities and the increasing number of large-scale and complex public spaces, there is an increase in public signage. Moreover, the information described on these signs tends to be diverse and complicated. Complex signs that contain multiple destinations or other information must be considered to determine not only the proper size, color, etc. but also the most effective arrangement of design elements. In the previous research, the cognitive utility of complex public signs was estimated using computer simulation software. In the current research, we focused on the objective estimation of the effectiveness of the results obtained in the previous research utilizing an eye mark recording system. Two cognitive engineering experiments clarified five points for improvement in the usability of complex signs, as follows: 1) Parallel construction of characters and pictograms is more efficient. 2) Grouping elements result in rapid recognition of information chunks. 3) Visual characters and pictograms are effective, along with proper density of information. 4) Specific arrangement of sign arrows is effective. 5) Figures on signs influence the sequence of information searches.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.96-104
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• 2003

This paper presents the measurement and correction method of PCB alignment errors for PCB screen printer. Electronic equipment is getting smaller and yet must satisfy high performance standard. Therefore, there is a great demand for PCB with high density. However conventional PCB screen printer doesn't have enough accuracy to accommodate the demand for high-resolution circuit pattern and high-density mounting capacity of electronic chips. It is because the alignment errors of PCB occur when it is loaded to the screen printer. Therefore, this study focuses on the development of the system which is able to measure and correct alignment errors with high-accuracy. An automatic optical inspection part measures the PCB alignment errors using machine vision, and the high-accuracy 3-axis stage makes correction for these errors. This system used two CCD cameras to get images of two fiducial marks of PCB. The centers of fiducial marks are obtained by using moment, gradient method. The first method is calculating the centroid by using first moment of blob, and the latter method is calculating the center of the circle whose equation is obtained by curve-fitting the boundaries of fiducial mark. The operating system used to implement the whole set-up is carried in Window 98 (or NT) environment. Finally we implemented this system to PCB screen printer.

• Journal of the Korean Society of Safety
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• v.29 no.2
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• pp.1-6
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• 2014

In this paper, safety certification products and safety condition of small transformer is analyzed in industries field and educational facilities. In transformer of 50places, absolute majority is step down transformer to measure of instrument. Most transformers were below 5kVA and 1~3kVA capacity was the mainstream. In industries field, 5 transformers were found without safety certification according to the Electrical Appliances Safety Control Act as cheap product prefer and lack of safety consciousness. Mark & number, voltage, date of manufacture of safety certification must show item of certification. However date of manufacture showed in product of 18%, 9places. As result of thermal imaging camera, running temperature of transformer was showed in below of target temperature. However as a narrow space of transformer and wall, power cable was touched on a ventilating flue in transformer. It was simple carelessness case that surface fouling and temperature ageing of transformer accelerate. Power poor connection, neglect of transformer in production equipment, fall damage by setup incongruity and ground omission were found in case of illogicality item of transformer.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.52-59
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• 2008

Most accident reconstruction or analysis depend on the coefficient of friction to estimate the vehicle speeds. Skid mark and coefficient of friction are usually utilized to calculate the velocity and behavior of vehicles. For a critical case such as traffic accident reconstruction, however, the initial velocity of the car should be calculated precisely. In this paper, emergency brake tests on ABS and Non-ABS brake system are conducted on the dry pavement asphalt road on speed 40, 60, 80 and 100 km/h respectively. The SWIFT sensor was established in the front wheel and rear wheel at driver side to measure the forces, moments and speeds of revolution of the tires. These tests results can be available to brake tests and accident reconstruction.

• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.90-95
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• 2008

The letters and marks on the hull of vessels are marked by welding bead or steel plate to resist the corrosion environment. It has done by manual work. So, it cause deterioration of welding quality and process delay and so on. The automated welding device for draft mark has developed partially in the field of shipbuilding. But it can be used for draft mark only. And it has caused a few problems about that workablity and movablity are decreased owing to the size and weight of device. So we developed the automated welding device that can be used for most letters and marks on the hull. It designed to 3 axises mobile robot include to ratoation axis and stand alone type controller with multi GUI base on imbedded windows.

• The Journal of the Korea Contents Association
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• v.3 no.1
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• pp.21-30
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• 2003

Retracing schemes using packet marking are currently being studied to protect network resources by isolating DDoS attack. One promising solution is the probabilistic packet marking (PPM). However, PPM can't use ICMP by encoding a mark into the IP identification field. Likewise, it can't identify the original source through a hash function used to encode trace information and reduce the mark size. In addition, the retracing problem overlaps with the result from the XOR operation. An algorithm is therefore proposed to pursue the attacker's source efficiently. The source is marked in a packet using a router ID, with marking information abstracted.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.942-948
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• 2021

The aim of this work is to help inform the decision for choosing a convenient material for the PGAA (Prompt Gamma Activation Analysis) collimator plug to be installed at the tangential channel of the Moroccan Triga Mark II Research Reactor. Two families of materials are usually used for collimator construction: a mixture of high-density polyethylene (HDPE) with boron, which is commonly used to moderate and absorb neutrons, and heavy materials, either for gamma absorption or for fast neutron absorption. An investigation of two different collimator designs was performed using N-Particle Monte Carlo MCNP6.2 code with the ENDF/B-VII.1 and MCLIP84 libraries. For each design, carbon steel and lead materials were used separately as collimator heavy materials. The performed study focused on both the impact on neutron beam quality and the neutron-gamma background at the exit of the collimator beam tube. An analysis and assessment of the principal findings is presented in this paper, as well as recommendations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.100-109
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• 2022

In this study, calibration technology that increases the alignment accuracy in large flexible flat panels was studied. For precise of calibration, a systematization of the calibration algorithm was established, and a calibration correction technique was studied to revise calibration errors. A coordinate systems of camera and UVW stage was established to get the global position of the mark, and equations for translational and rotational calibration were systematically derived based on geometrical analysis. Correction process for the calibration data was carried, and alignment experiments were performed sequentially in cases of the presence or absence of calibration-correction. Alignment results of both calibration correction and non-calibration correction showed accuracy performance less than 1㎛. On the other hand, the standard deviation in calibration-correction is smaller than non-calibration correction. Therefore, calibration correction showed improvement of the alignment repeatability.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.357-365
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• 1998

목적: 치과용 수복재료의 방사선 불투과성은 매우 다양하다. 따라서 다양한 수복재료의 방사선 불투과성을 인지하여 치질과 비교하면 이차우식의 진단에 도움이 될 수 있다. 도재의 방사선 불투과성에 따라 적절한 luting cement의 선택이 가농해진다. 수복재료의 방사선 불투과성은 알루미늄 step wedge 의 후경과 방사선 불투과성과의 상관관계 의해 측정된다. 본 연구의 목적은 CAD/CAM용 도재와 이틀의 접착에 쓰이는 접착재료의 방사선 불투과성을 조사해 적절한 재료의 선택과 이차우식 진단의 효율결정에 도움이 되게 하는데 있다. 방법: 본 실험에서는 CAD/CAM용 도재인 Vita MarkII, Dicor MGC와 이의 접착에 사용되는 Z-100, 그리고 luting cement인 Duo cement, Scotchbond resin cement를 사용해 방사선 불투과성을 측정하였다. 시편 제작을 위해 도재를 저속절단기로 두께 2mm, 3mm로 절단하였으며 Z-100과 cement시편은 두께 2mm와 3mm, 직경 7.0mm의 금속 주형을 제작한 후 재료를 양쪽 면에 유리판을 대고 조임쇠로 압접하였으며 광조사기를 사용하여 각 재료마다 두 가지 두께로 10개씩 100개의 시편을 제작하였다. 치질의 시편을 얻기 위해 교정 목적으로 최근에 발거된 정상적인 상악 소구치를 저속 절단기를 사용하여 협설측 교두정을 기준 삼아 2mm, 3mm 두께로 절단하였으며 방사선 불투과성의 기준을 위해 12개의 step으로 구성된 12mm두께의 aluminum step wedge를 사용하였다. Kodak E-Speed occlusal film에 aluminum step wedge와 시편들을 위치시킨 후 70kVp, 7mA, 2.16mm aluminum filtration으로 고정된 dental X-ray unit을 사용하여 target과 film 사이의 거리는 25cm, 노출시간은 0.2초로 하여 방사선 촬영을 한 다음, 현상된 방사선 사진상에 나타난 방사선 불투과성을 X-rite 301 densitometer를 이용하여 측정한 값들의 평균을 냈다. 얻어진 결과는 one-way ANOVA Duncan test(P<0.01)로 검증하였다. 결론: 1. Dicor MGC의 방사선 불투과성은 법랑질보다 약간 높게 나타났다.(P<0.01) 2. Vita Mark Il는 상아질보다 낮은 방사선 불투과성을 보였다.(P<0.01) 3. Z-100과 Luting cement들의 방사선 불투과성은 법랑질보다 높았다. Duo cement가 방사선 불투과성이 가장 높았고 그 다음이 Z-100, 그리고 Scotchbond resin cement 순이었다. 4. Z-100과 2종류의 방사선 불투과성 luting cement들은 Vita Mark II 와 같이 사용하면 2차우식 진단에 도움이 된다.

• Korean Journal of Human Ecology
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• v.20 no.3
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• pp.665-675
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• 2011

The purpose of this study was to examine the attitude toward food safety and the HACCP of college students in Daejeon. 51.9% of respondents had experienced food poisoning. The main symptoms of food poisoning were diarrhea(73.4%), stomachache(57.3%), and vomiting(24.7%). Most students answered that food hygiene was important and more students in private residences recognized the importance of food hygiene than in non-private residences (p<0.05). More information about hygine was obtained from TV & radio(44.9%) than the internet(38.1%). Half of them were afraid of food safety and more females felt unsafe about food sold than males(p<0.01). 37.6% of them were aware of HACCP, more females(44.6%) than males(28.4%) had such knowledge(p<0.001). The more information they had on HACCP, the higher the perception of the HACCP mark(p<0.001). 45.4% of them had seen HACCP mark on food packages and more females had seen it than males(p<0.001), 64% of them purchased HACCP products, The more information they had on HACCP, the more experience they had with HACCP consumption(p<0.001), 44% of them were willing to buy HACCP products. Males(32.3%) wanted to buy HACCP products for their health and females(49.6%) wanted to buy HACCP products if they were the same price (p<0.001). Education about food hygiene and HACCP should be conducted for collage students' health though TV, radio, and the internet.