• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.454-459
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• 2013

Recently, remote phosphors have been reported for application to white LEDs to provide enhanced phosphor efficiency compared with conventional phosphor-based white LEDs. In this study, a remote phosphor was produced by coating via screen printing on a glass substrate with different numbers of phosphor coating. The paste consists of phosphor, lowest softening glass frits, and organic binders. The remote phosphor could be well controlled by varying the phosphor content rated paste. After mounting the remote phosphor on top of a blue LED chip, CCT, CRI, and luminance efficiency were measured and values of 5300 K, 62, and 117 lm/W were respectively obtained in the 80 wt% phosphor with 3 coating layers sintered at $800^{\circ}C$.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.322-323
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• 2015

Traditional rotation type large beacon was characterized by frequent failure, long repair time and high cost etc. These problems are caused by traditional light sources(metal halide lamps or tungsten halogen lamps). In order to solve these problems, IALA standards-based(efficiency and reliability) large LED beacon technologies are needed. we developed by applying a LED. The object of the this project, to design a reflective optics and the high power LED lighting engine module. And to develop a rotational speed control system for controlling flash pattern of beacon. As a result, to develop of LED beacon for landfall mark that distance to reach the light 20NM to 27NM.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.267-270
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• 2016

Currently, tire has a variety of information to know the information of the tire are displayed on the tire side. the market are marked with raised letters showing a variety of information relating to the tires. Such information enables people and tire related companies to distinguish between tires upon the information marked on the tires. Generally, people see the information including max press, manufacturing date, etc. Accordingly, studies on automated recognition of raised letters on tire by using image processing technology have been presented consistently. However, they lack a method for recognition of letters and improvement of the recognition. Moreover, the raised letters have been previously recognized through image processing. Further, to obtain the character recognition of a conventional side in video, it is suitably utilized the effects of lighting time of acquisition, so as part of the background and the character has a gray level values between approximately the same, is the part that is not relatively clear are many scattered. In this paper, we see the characters of the tire side using the laser sensor, recognition, was designed for character recognition of the tire side.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.2
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• pp.104.1-104.1
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• 1997

The purpose of this study is to grasp the characteristics of user''''s response to perceived safety and visual preferences for outdoor green spaces by the types of campus layouts. This research was investigated by color slide ratings and questionnaire survey to the students who are majoring in Landscape architecture in three universities locating at Taegu area. Two research sites have similarities in many ways but have differences in campus land form and design type such as ''''Closed'''' and ''''Open'''' types. Major results were summarised as follows ; 1. As a result of the slide test, the high degree of visual preference was shown in the campus that is ''''Closed'''' type. However the degree of perceived safety was lower than that of in Youngnam Univ. campus. 2. According to the result of the comparative analysis between user''''s perceived safety and visual preferences in each campus, the degree of perceived safety at ''''Closed'''' type was lower than that of ''''Open'''' type, but the degree of visual satisfactioni was higher at ''''Closed'''' type. 3. The factors affecting visual preference in campus were shown as density of wood, land form, and diverse type of the spaces. On the other hand, the factors affecting perceived safety were ''''enclosed space by wood'''' at the day time, and ''''the condition of lighting'''' at night. 4. Regarding gender differences in sensation of each space variables, female users showed higher satisfactio on the scenic beauty. 5. Regression analysis showed that general satisfation was determined by the variables such as ''''arrangement'''', familiarity'''', ''''cleanness'''', and ''''closed feeling'''', in Kyungbook Univ. And in Youngnam Univ. , the variables were ''''texture'''', ''''perceived beauty'''', ''''cleanness'''', and ''''complexity'''' respectively. 6. In conclusion, campus users wanted the outdoor spaces that have various land form and somewhat ''''open-closed'''' mixture type, which has a good ''''Edge Effect'''' to satisfy both aspects in safety and visual preferneces.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.2
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• pp.104-116
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• 1997

The purpose of this study is to grasp the characteristics of user's response to perceived safety and visual preferences for outdoor green spaces by the types of campus layouts. This research was investigated by color slide ratings and questionnaire survey to the students who are majoring in Landscape architecture in three universities locating at Taegu area. Two research sites have similarities in many ways but have differences in campus land form and design type such as 'Closed' and 'Open' types. Major results were summarised as follows ; 1. As a result of the slide test, the high degree of visual preference was shown in the campus that is 'Closed' type. However the degree of perceived safety was lower than that of in Youngnam Univ. campus. 2. According to the result of the comparative analysis between user's perceived safety and visual preferences in each campus, the degree of perceived safety at 'Closed' type was lower than that of 'Open' type, but the degree of visual satisfactioni was higher at 'Closed' type. 3. The factors affecting visual preference in campus were shown as density of wood, land form, and diverse type of the spaces. On the other hand, the factors affecting perceived safety were 'enclosed space by wood' at the day time, and 'the condition of lighting' at night. 4. Regarding gender differences in sensation of each space variables, female users showed higher satisfactio on the scenic beauty. 5. Regression analysis showed that general satisfation was determined by the variables such as 'arrangement', familiarity', 'cleanness', and 'closed feeling', in Kyungbook Univ. And in Youngnam Univ. , the variables were 'texture', 'perceived beauty', 'cleanness', and 'complexity' respectively. 6. In conclusion, campus users wanted the outdoor spaces that have various land form and somewhat 'open-closed' mixture type, which has a good 'Edge Effect' to satisfy both aspects in safety and visual preferneces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.350-354
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• 2017

In this study, the DIAlux program was simulated for the optimal conditions of daylight and artificial light sources(LED) in a glass greenhouse. From the results of the daylight simulation, the optimal design conditions for the glass greenhouse were established, which had a $90^{\circ}$ installation angle and a higher transmittance of glass. In the case of growing lettuce in a glass greenhouse, it was compared with artificial light sources, the artificial light source (LED) was used to produce a power consumption effect of 41%. These results suggest that lettuce be grown in an energy saving glass greenhouse.

• Journal of Power Electronics
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• v.15 no.2
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• pp.555-566
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• 2015

A TRIAC dimming LED driver that can control the brightness of LED arrays for a wide range of source voltage variations is proposed in this paper. Unlike conventional PWM LED drivers, the proposed LED driver adopts a TRIAC switch, which inherently guarantees zero current switching and has been proven to be quite reliable over its long lifetime. Unlike previous TRIAC type LED drivers, the proposed LED driver is composed of an LC input filter and a variable switched capacitance, which is modulated by the TRIAC turn-on timing. Thus, the LED power regulation and dimming control, which are done by a volume resistor in the same way as the conventional TRIAC dimmers, can be simultaneously performed by the TRIAC control circuit. Because the proposed LED driver has high efficiency and a long lifetime with a high power factor (PF) and low total harmonic distortion (THD) characteristics, it is quite adequate for industrial lighting applications such as streets, factories, parking garages, and emergency stairs. A simple step-down capacitive power supply circuit composed of passive components only is also proposed, which is quite useful for providing DC power from an AC source without a bulky and heavy transformer. A prototype 60 W LED driver was implemented by the proposed design procedure and verified by simulation and experimental results, where the efficiency, PF, and THD are 92%, 0.94, and 6.3%, respectively. The LED power variation is well mitigated to below ${\pm}2%$ for 190 V < $V_s$ < 250 V by using the proposed simple control circuit.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.339-348
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• 2017

Power supply for railway cars can be divided into propulsion system power supply and auxiliary power units (APU). The propulsion system power supply is for propulsion of railway cars, and regenerative braking; the APU provides power for the air compressor, lighting, car control and other auxiliary parts. According to high voltage and high current specifications, generally, an insulated-gate bipolar transistor (IGBT) is adopted for the switching component. For appropriate switching operation, a gate driver unit (GDU) is essentially required. In this paper, the technical trends of GDU for railway cars are analyzed and a design consideration for IGBT GDU is described.

• International Journal of Knowledge Content Development & Technology
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• v.11 no.1
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• pp.65-84
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• 2021

Our understanding of how barriers to access systematically varies with the compositional and contextual characteristics of users is incomplete. Using a public university library in Ghana, this study assessed the heterogeneous barriers or constraints students encounter in accessing electronic resources based on their demographic and contextual attributes. A descriptive survey design was adopted and structured questionnaires were administered randomly to 558 students in the four constituent colleges of the University of Cape Coast, Ghana. Data were collected and analysed using SPSS and descriptive statistics were generated. The results revealed that students faced six key challenges in accessing electronic information resources in the library namely delays in download of information, poor internet connectivity, and limited accessibility of university portal, inadequate computers in the library, poor lighting and limited ancillary services (on the spot printing facilities), with differences based on gender, academic level, and college affiliation. Only 24% males and 26% females had no challenges or problems with delays in download of electronic information. About three-fourth of all users had poor internet connectivity and complained about inadequate computers associated with accessing electronic resources. 40% percent of undergraduate students in the Colleges of Education Studies, Agriculture and Natural Sciences, and Humanities and Legal Studies each encountered four to six simultaneous challenges. Irrespective of gender, first year undergraduate students in all the four colleges were the least likely to report multiple challenges. This suggests the need for targeted and context-specific interventions to address the identified challenges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.50-56
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• 2021

This study examines 3D scanning and how it is used in the construction field. 3D scanning technology was applied to a real space and compared with drawings in the planning and construction stages. 3D scanning technology has been widely applied in the field of construction, design, construction, and safety. The results of comparing 3D scanning data with drawings are as follows. First, the external shape and dimensions do not show much difference. Second, the internal shape and dimensions are different. Third, indoor lighting layouts are different in all buildings. 3D scanning should be an essential element in the construction stage before completion and should be used for supervision tasks such as material management, improving the efficiency of construction, and safety management through continuous 3D scanning using automation and robots. Follow-up studies in the field of architecture, such as BIM and process management, will be needed.