• Korean Journal of Digital Imaging in Medicine
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• v.13 no.4
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• pp.145-151
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• 2011

The purpose of this study is to know some changes of resolution and image if we remove scattered ray using lead plate when doing lumbar lateral projection. Using 3 DR system(2 FD types, 1 CCD type) equipments and 2 film system equipments, we gain the image whether the phantom of abdomen equivalent sticking resolution chart has lead plate or not, whether we do collimation or not. Also, we use ion chamber, measure radiation exposure rate and change to entrance surface dose from it. we gain that images in the greatest condition of taking in clinic. 5 people in this group decoded resolution with our eyes, measured thickness of images and compared them from each equiments. Resolution has difference to size of collimation in DR FD type. Also there is no difference the original image with the new image which we abbreviated mAs. In DR CCD type, resolution didn't have difference whether lead plate is or not and whether we do collimation or not. In film type, existing or nonexisting of lead plate didn't influence on resolution. Lead plate makes the quality of image higher due to reducing scattered ray, it doesn't influence on resolution.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.451-451
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• 2000

This study aims for the optimization of process conditions in a fixed-bed catalytic reactor system with a circulating molten salt bath, in which partial oxidation of propylene to acrolein takes place. Two-dimensional pseudo-homogeneous model is adopted with estimation of suitable parameters and its validity is corroborated by comparing simulation result with experimental data. The temperature of the molten salt and the feed composition are found to exercise significant influence on the yield of acrolein and the magnitude of hot spot. The temperature of the molten salt is usually kept constant. This study, however, suggests that the temperature of the molten salt must be axially adjusted so that the abrupt peak of hot spot should not appear near the reactor entrance. The yield of acrolein is maximized and the position and the magnitude of hot spot are optimized by the method of the iterative dynamic programming (IDP).

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.4
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• pp.178-187
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• 2003

In this study, ventilation flow rate and pressure rise through a tunnel are simulated numerically using computational fluid dynamics (CFD) for various conditions such as roughness height of the surface of tunnel, swirl angle and hub/tip ratio of jet fan, and entrance and exit effects. By using a modified wall function, friction factor can be predicted with respect to the Moody chart within 10% of error for the circular pipe flow and 15% for the present tunnel. For more accurate design, the effect of the swirl angle and hub/tip ratio of jet fan, which is not included in the theoretical equation of pressure rise by jet fan needs to be considered.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.18-25
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• 2012

This work investigated the influence of the chimney dimensions(exit and entrance length, and diameter) on the heat transfer of a vertical cylinder in a duct. The measured mass transfer rates for the natural convection of vertical cylinder in a duct were presented for Prandlt number 2,094, Rayleigh number in the range of $4.55{\times}10^9$, $5.79{\times}10^{10}$, and $1.69{\times}10^{11}$. Experiments were performed using a copper sulfate electroplating system to simulate heat transfer based upon the analogy concept. The diameter of the duct was varied from 0.06 m to 0.14 m, and the heights from 0.30 m to 1.10 m. Nusselt numbers measured at open channel condition agreed well with the existing laminar heat transfer correlations for vertical plate developed by Le Fevre. The increase of the exit length enhanced the heat transfer up to a certain duct height but further increase does not affects the heat transfer. The heat transfer decreased with increasing the entrance length up to a certain duct height and was constant at further increase. The Nusselt number decreased with increasing the diameter of duct, until Nusselt number becomes similar to that at open channel beyond a certain diameter.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.45-51
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• 2022

Fear of contact exists due to the prevention of the spread of infectious diseases such as COVID-19. When using the common entrance door of an apartment, access is possible only if the resident enters a password or obtains the resident's permission. There is the inconvenience of having to manually enter the number and password for the common entrance door to enter. Also, contactless entry is required due to COVID-19. Due to the development of ICT, users can be easily identified through the development of face recognition and voice recognition technology. The proposed method detects a visitor's face through a CCTV or camera attached to the common entrance door, recognizes the face, and identifies it as a registered resident. Then, based on the registered information of the resident, it is possible to operate without contact by interworking with the elevator on the server. In particular, if face recognition fails with a hat or mask, the visitor is identified by voice or additional authentication of the visitor is performed based on the voice message. It is possible to block the spread of contagiousness without leaving any contactless function and fingerprint information when entering and exiting the front door of an apartment house, and without the inconvenience of access.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.12
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• pp.21-29
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• 2019

The purpose of the study is to be the pedestrian integrated circulation system of malling route and the third route in Mixed-use Building based on User Behavior. The study has performed by the following approaches: Initially, literature reviews are performed related to a pedestrian route by user in mixed-use building. Second, general and stroller users moving route are analyzed based on the outcome of the case study. Finally, the study develops the efficient pedestrian integrated circulation system of malling route and the third route in Mixed-use Building. According to the study, the following conclusions were made: First, An integrated plan for escalators and EVs, which are accessible to both users and strollers, is needed. Second, The entrance automatic door and circulation elements should be connected for continuous move by the stroller users. Finally, The circulation system of complex buildings should be a simple spatial structure and route plan that users can easily recognize.

• Korean Journal of Comparative Education
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• v.27 no.4
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• pp.155-186
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• 2017

The purpose of the study is to analyze the operational case of gap year which can explore about guidance in some times before college entrance or during college life in the universities of main nations(England, American, and Japan) and draw from some implications for possibility of it's introduction in Korean university. It means that before students enter the college after finishing high school, they have various guidance activity and voluntary service activity for experiencing self-understanding out of regular curriculum. The study analyzed four universities in America, two universities in England, and one university in Japan. The main results indicate that the gap year can divide into system and university assisting finance. Based on the results and their implications of gap year case analysis in universities of England, America, and Japan, the study suggests that it needs to consolidate the related system of university and assist some finances, and systematic steps such as career exploration, career decision-making, career plan, and career preparation should be constructed.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.660-665
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• 2006

본 논문에서는 유비쿼터스 컴퓨팅 구현에 있어서 중요 핵심 요소 기술인 실내에서의 사용자의 위치를 인식하면서 동시에 사용자를 식별하는 방법에 대해 제안하고자 한다. 제안된 사용자 식별 방법은 초음파 센서의 물체까지의 거리를 측정할 수 있는 특성에 기초하여 구성원의 키 높이의 다름을 주요한 식별 특성으로 이용하는 방법이다. 또한 사용자 식별을 수행하는 것과 동시에 식별된 사용자가 센서가 장착된 문을 통과하여 들어왔는지 나갔는지를 감지하는 출입 감지 방법도 제안한다. 기본적인 출입 감지 방법의 아이디어는 2개 초음파 센서의 물체 감지 순서를 이용하여 개발되었다. 제안된 방법의 성능 검증을 위해 1단계의 프로토타입을 만들었으며, 개발된 프로토타입을 이용하여 3명의 가족 구성원으로 이루어진 일반 가정집의 화장실에 장착하여 성능 실험을 실시하였다. 실험 결과 100%의 사용자 식별 성능 및 평균 98%의 출입 감지 성능을 얻었다.

• Journal of the Semiconductor & Display Technology
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• v.6 no.2 s.19
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• pp.59-63
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• 2007

Radio Frequency Identification (RFID) is a common term for technologies using micro chips that are able to communicate over short-range radio and that can be used for identifying physical objects. RFID technology already has several application areas and more are being envisioned all the time. While it has the potential of becoming a really ubiquitous part of the information society over time, there are many security and privacy concerns related to RFID that need to be solved. This paper proposes a method which could protect private information and ensure RFID's identification effectively storing face feature information on RFID tag. This method improved linear discriminant analysis has reduced the dimension of feature information which has large size of data. Therefore, face feature information can be stored in small memory field of RFID tag. The proposed algorithm in comparison with other previous methods shows better stability and elevated detection rate and also can be applied to the entrance control management system, digital identification card and others.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.169-171
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• 2013

The ships always have had the risk of collision. There are also a number of near-miss situations especially in the congested area such as port entrance, restricted waters and crossing point of the ship's route. In those areas, the navigator might have more stress than other areas. If the collision risk of decided area is calculated, it might be possible to analyse the human factors by using this data. It is also helpful for deciding a position of aids to navigation or any other system for the safety navigation. For this purpose, the model of collision risk with AIS data has been explained in this paper. The calculated result from the proposed model has been examined by using the simulation.