• 한국전기전자재료학회논문지
• /
• 제37권5호
• /
• pp.486-493
• /
• 2024

Lighting has been used for a long time as a medium to convey brightness from darkness, and through incandescent lamps and fluorescent lamps, LED light sources have now become the standard in the lighting industry. Recently, the lighting equipment industry has been undergoing rapid digital transformation, starting with smart lighting, and is evolving into smart lighting customized for individuals and spaces through the development of IoT technology, cloud-based services, and data analysis. However, the blue light emitted from digital devices (computers, smartphones, tablets, etc.) or LED lights stimulates the melanopsin in the optic ganglion cells in the retina of the eye, which in turn stimulates the secretion of melatonin through the pineal gland, which regulates the secretion of melatonin. This can reduce sleep quality or disrupt biological rhythms. This interaction between blue light and melatonin has such a significant impact on human sleep patterns and overall health that it is essential to reduce exposure to blue light, especially in the evening. Human-centered lighting refers to lighting that takes into account the effects of light on the physical and mental areas, such as human activity and awakening, improvement of sleep quality, and health management. Many research institutes study the effects in the visible area and the non-visible area. By studying the impact, it is expected to improve the quality of human life. In this study, we plan to study ways to implement human-centered lighting by collecting sunrise and sunset data and linking commercialized LED packages and control devices with open-source hardware.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.22.2-22.2
• /
• 2011

Reliability and degradation mechanism of conventional phosphor-converted white GaN-based light-emitting diodes (LEDs) were investigated. Under electro-thermal stress condition, the optical output degraded rapidly at the initial stress time accompanied by the change of chromatic properties. This could be attributed to the optical degradation of packaged materials, in particular, the browning of encapsulants and the darkening of reflective packages. At longer stress times, the optical output gradually decreased according to the degree of the reverse leakage currents, namely, the generation ofnonradiative recombination defects. This indicates that the optical degradation of white LEDs are dominated by the darkening of packaged materials and the generation of defects depending on the injection current and ambient temperatures. Using analyses of electroluminescence spectra, optical microscopy, electrical, optical, and thermal properties, optical degradations of white LEDs are discussed.

• Journal of Information Display
• /
• 제13권1호
• /
• pp.1-6
• /
• 2012

Decreasing the thermal resistance is the critical issue for high-brightness light-emitting diodes. In this paper, the effects of some design factors, such as chip size (24 and 35 mil), substrate material (AlN and high-temperature co-fired ceramic), and die-attach material (Ag epoxy and PbSn solder), on the thermal-dissipation characteristics were investigated. Using the thermal transient method, the temperature sensitivity parameter, $R_{th}$ (thermal resistance), and junction temperature were estimated. The 35-mil chip showed better thermal dissipation, leading to lower thermal resistance and lower junction temperature, owing to its smaller heat source density compared with that of the 24-mil chip. By adopting an AlN substrate and a PbSn solder, which have higher thermal conductivity, the thermal resistance of the 24-mil chip can be decreased and can be made the same as that of the 35-mil chip.

• 마이크로전자및패키징학회지
• /
• 제19권4호
• /
• pp.51-56
• /
• 2012

습식공정으로 thermal via용 SI 관통 via를 형성하기 위해 TMAH 용액의 농도와 온도에 따른 Si 기판의 이방성 습식식각 거동을 분석하였다. TMAH 용액의 온도를 $80^{\circ}C$로 유지한 경우, 5 wt%, 10 wt% 및 25 wt% 농도의 TMAH 용액은 각기 $0.76{\mu}m/min$, $0.75{\mu}m/min$ 및 $0.30{\mu}m/min$의 Si 식각속도를 나타내었다. 10 wt% TMAH 용액의 온도를 $20^{\circ}C$와 $50^{\circ}C$로 유지시에는 각기 $0.07{\mu}m/min$와 $0.23{\mu}m/min$으로 식각속도가 저하하였다. Si 기판의 양면에 동일한 형태의 식각 패턴을 형성하여 $80^{\circ}C$의 10 wt% TMAH 용액에 장입하고 5시간 식각하여 깊이 $500{\mu}m$의 관통 via hole을 형성하였다.

• 한국치위생학회지
• /
• 제12권5호
• /
• pp.943-952
• /
• 2012

Objectives : The purpose of this study was to examine the impact of the systemic osteoporosis of Korean adults on their periodontal diseases and CPI index based on the data of their systemic osteoporosis. Methods : The third-year raw data of the 4th 2009 National Health & Nutrition Survey that turned out to be representative and reliable were utilized. The subjects in this study were 7,285 adults who were over the age of 19 and got both of health and dental checkups. As for data analysis, the statistical packages PASW 19.0 and SAS 9.0 were employed. Results : The most periodontal diseases were found in those who had osteoporosis in the entire parts, entire femur, femoral neck and spiral bone, but there was no significant relationship between periodontal diseases and osteoporosis. As for the connections between peridontal diseases and osteoporosis, the adults who had femoral neck osteoporosis had a 2.057-fold less bone mass than those who had a normal bone density in this part, and the former's periodontal diseases increased in proportion to that. There was consequently a statistically significant relationship between the two(p<0.05). Among the prevalence factors of osteoporosis, a lower entire femur bone mineral density led to a lower CPI index(p<0.01), and a lower femoral neck bone mineral density led to a higher CPI index(p<0.05). Thus, there was a significant relationship between osteoporosis and the oral health indicator. Conclusions : The above-mentioned findings confirmed that in terms of the relationship among the periodontal diseases, CPI index and osteoporosis of Korean adults, a higher risk of osteoporosis affected the increase of chronic periodontal diseases.

• 디지털산업정보학회논문지
• /
• 제11권1호
• /
• pp.69-78
• /
• 2015

Internet of Things(IoT) is electronic devices and household appliances use wireless sensor network in environment of high speed wireless network and LTE mobile service. The combination of the development of Internet and wireless network led to development of new forms of service such as electronic devices and household appliances can connect to the Internet through various sensors and online servers such as a Home Network. Even though Internet of Things is useful, there are problems in Internet of Things. In environment of Internet of Things, information leakage could happens by illegal eavesdropping and spoofing. Also illegal devices of wireless communication interference can cause interfere in Internet of things service, physical damage and denial of service by modulation of data and sensor. In this thesis, it will analyze security threats and security vulnerability in environment of mobile services and smart household appliances, then it will suggest plan. To solve security issues, it is important that IT and RFID sensor related companies realize importance of security environment rather than focus on making profit. It is important to develop the standardized security model that applies to the Internet of Things by security-related packages, standard certification system and strong encrypted authentication.

• 한국세라믹학회지
• /
• 제49권1호
• /
• pp.111-117
• /
• 2012

Dependencies of thermal properties on the crystallization behavior of $0.9CaMgSi_2O_6-0.1MgSiO_3$ glass-ceramics were investigated as a function of heat-treatment temperature from $750^{\circ}C$ to $950^{\circ}C$. The crystallization behavior of the specimens depended on the heat-treatment temperature, which could be evaluated by differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis by the Rietveld-reference intensity ratio (RIR) combined procedure. With an increase of the heat-treatment temperature, the thermal conductivity and thermal diffusivity of the heat-treated specimens increased. These results could be attributed to the increase of crystallization with heat-treatment temperature. However, the specific heat capacity of the heat-treated specimens was not affected by the heat-treatment temperature. The thermal conductivities measured from $25^{\circ}C$ to $100^{\circ}C$ were also discussed for application to lighting-emitting diode (LED) packages and substrate materials.

• 정보관리연구
• /
• 제41권4호
• /
• pp.69-91
• /
• 2010

제한된 예산, 고가의 패키지 구독비, 출판사 주도의 라이선스 협상 등의 불리한 환경에서 자관의 실정에 맞는 전자저널을 구성하기 위해 도서관은 전자저널 이용데이터를 수집하고 분석해야 한다. 본 연구는 전자저널 이용통계 연구 동향 및 COUNTER 3판에 근거한 이용통계 제공 현황을 살펴보고 현장에서 쉽게 활용 가능한 이용통계 분석의 가이드라인을 제시하고자 하였다. 현재 제공되는 이용통계 보고서를 기반으로 분석할 수 있는 핵심 이용통계치로 저널별 원문이용도, 저널이용률, 원문이용단가, 고이용군, 저이용군을 제안함으로써 전자저널 관리를 위한 이용통계의 효과적인 활용 방안을 다루었다.

• Design & Manufacturing
• /
• 제14권4호
• /
• pp.58-64
• /
• 2020

Lately, the development of the semiconductor industry has led to the miniaturization of electronic devices. Therefore, semiconductor wafers of very thin thickness that can be used in Multi-Chip Packages are required. There is active research on the backgrinding process to reduce the thickness of the wafer. The backgrinding process polishes the backside of the wafer, reducing the thickness of the wafer to tens of ㎛. The equipment that performs the backgrinding process requires ultra-precision. Currently, there is no full auto backgrinding equipment in Korea. Therefore, in this study, ultra-precision backgrinding equipment was designed. In addition, finite element analysis was conducted to verify the equipment design validity. The deflection and structural stability of the backgrinding equipment were analyzed using finite element analysis.

• 한국경제지리학회지
• /
• 제12권4호
• /
• pp.438-453
• /
• 2009

외국인 투자를 유치하여 지역개발을 도모하려는 전략은 여러나라에서 쓰이고 있고, 이는 우리나라도 마찬가지이다. 본 연구는 외국인 투자를 대거 유치하여 지역성장을 이뤘다는 평가를 일각에서 받고 있는 영국 웨일즈 지역의 사례를 심층적으로 분석하여 과연 외국인 투자 중심의 지역발전 전략이 유효한지를 알아보려 하였다. 기존 문헌들을 비판적으로 검토 종합한 결과, 웨일즈는 투자 유치 총량을 기준으로 보면 성공적이라 할 수 있지만 상당한 부작용도 있었음을 알 수 있었다. 웨일즈 정부는 세제상의 혜택, 정상적인 계획심의 과정 생략, 개발유보지 제공 등, 각종 혜택을 주었는데 반해, 기업들이 내놓은 성과는 미미했다. 숙련 노동보다는 비숙련 노동, 연구개발보다는 단순조립중심의 공장들이 많이 유치되었고 외국인 투자기업들은 지역의 기업과의 연계도 강하지 않았다. 웨일즈의 경험이 우리에게 주는 교훈은, 외국인 투자만 유치하면 지역발전이 저절로 보장될 것이라는 환상을 버려야 하며, 투자 유치과정에서 중앙정부와 지방정부, 또 지방정부들간에 긴밀한 협력을 통해, 외국인 투자기업을 적절히 규제할 필요가 있는 경우도 있다는 점이다.