• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1516-1522
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• 2014

A series of 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ surface treatments were applied to $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates. The $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates were synthesized using a co-precipitation method. Sample (a) was left pristine and variations of the 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ were applied to samples (b), (c) and (d). XRD was used to verify the space group of the samples as R$\bar{3}$m. Additional morphology and particle size data were obtained using SEM imagery. The $Al_2O_3$ coating layers of sample (b) and (d) were confirmed by TEM images and EDS mapping of the SEM images. 2032-type coin cells were fabricated in a glove box in order to investigate their electrochemical properties. The cells were charged and discharged at room temperature ($25^{\circ}C$) between 2.0V and 4.8V during the first cycle. The cells were then charged and discharged between 2.0V and 4.6V in subsequent cycles. Sample (d) exhibited lower irreversible capacity loss (ICL) in the first charge-discharge cycle as compared to sample (c). Sample (d) also had a higher discharge capacity of ~250 mAh/g during the first and second charge-discharge cycles when compared with sample (c). The rate capability of the $Al_2O_3$-coated sample (b) and (d) was lower when compared with sample (a) and (c). Sample (d), coated with $Al_2O_3$ after the surface treatment with $(NH_4)_2SO_4$, showed an improvement in cycle performance as well as an enhancement of discharge capacity. The thermal stability of sample (d) was higher than that of the sample (c) as the result of DSC.

• 대한소아치과학회지
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• 제36권2호
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• pp.199-208
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• 2009

본 연구는 기존의 $DIFOTI^{TM}$ 시스템의 문제점을 개선하고자 LED와 디지털 카메라를 결합한 발전된 형태의 prototype DIFOTI시스템을 만들고, 이를 기존 시스템과 비교 평가하기 위하여 인공 우식 용액으로 탈회시킨 법랑질 시편에 대하여 1일부터 7일까지 영상을 촬영하고 분석하여 다음과 같은 결과를 얻었다. 1. 실험 기간에 따라 두 시스템 모두 우식 법랑질의 광투과도(index of transillumination)가 감소하는 양상을 보여 주었다. 2. $DIFOTI^{TM}$ 시스템에 비해 prototype DIFOTI 시스템에서 건전 법랑질과 탈회 법랑질 간의 발광도(intensity of luminance) 차이가 더 적게 나타나는 양상을 보였다. 이상의 결과를 종합해보면 prototype DIFOTI 시스템은 전류 소모량이 적은 LED를 사용하여 배터리를 사용한 무선 시스템으로의 개발 가능성을 보여 주었고, 디지털 카메라는 디지털 영상 기술의 발달과 함께 무선 전송 시에도 매우 높은 화질을 기대할 수 있어 차후에 보다 작고 사용이 편리한 DIFOTI 시스템을 개발할 수 있는 가능성이 크다 할 수 있다.

• 전기화학회지
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• 제7권3호
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• pp.131-137
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• 2004

Sol-gel method which provides better electrochemical and physiochemical properties compared to the solid-state method was used to synthesize the material of $LiFe_yMn_{2-y}O_4$. Fe was substituted to increase the structural stability so that the effects of the substitution amount and sintering temperature were analyzed. XRD was used for the structural analysis of produced material, which in turn, showed the same cubic spinel structure as $LiMn_2O_4$ despite the substitution of $Fe^{3+}$. During the synthesis of $LiFe_yMn_{2-y}O_4$, as the sintering temperature and the doping amount of Fe(y=0.05, 0.1, 0.2)were increased, grain growth proceeded which in turn, showed a high crystalline and a large grain size, certain morphology with narrow specific surface area and large pore volume distribution was observed. In order to examine the ability for the practical use of the battery, charge-discharge tests were undertaken. When the substitution amount of $Fe^{3+}\;into\;LiMn_2O_4$ increased, the initial discharge capacity showed a tendency to decrease within the region of $3.0\~4.2V$ but when charge-discharge processes were repeated, other capacity maintenance properties turned out to be outstanding. In addition, when the sintering temperature was $800\~850^{\circ}C$, the initial capacity was small but showed very stable cycle performance. According to EVS(electrochemical voltage spectroscopy) test, $LiFe_yMn_{2-y}O_4(y=0,\;0.05,\;0.1,\;0.2)$ showed two plateau region and the typical peaks of manganese spinel structure when the substitution amount of $Fe^{3+}$ increased, the peak value at about 4.15V during the charge-discharge process showed a tendency to decrease. From the previous results, the local distortion due to the biphase within the region near 4.15V during the lithium extraction gave a phase transition to a more suitable single phase. When the transition was derived, the discharge capacity decreased. However the cycle performance showed an outstanding result.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.105-110
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• 2009

The On Line Electric Vehicles(OLEV) that can pick up inductive power from underground coils on driving with high efficiency have been developed this year, and is now proposed in this paper. The IPS(Inductive Power Supply) system consists of power supply inverters, power supply rails, pick up modules, and a regulator. There are 3 generations of IPS have been developed so far, and the $4^{th}$ generation IPS is being developed. The $1^{st}$ generation has been demonstrated this Feb. 27, which is equipped with mechanically auto tracking pick-up module with 1cm air gap, and showed 80% power efficiency. The $2^{nd}$ generation IPS applied to an 120kW (average)/240kW(peak) motor powered electric bus has 17cm air gap with 72% power efficiency. For the $2^{nd}$ generation IPS, the Power supply inverter has 440V, 3phase input and 200A @ 20kHz output. The test power supply rail of 240m long is segmented by 60m each, where newly developed core structure and power cable are constructed under the road covered with asphalt of 5cm thickness. The pick-up modules which consist of core, winding wire, and rectifiers are fixed to the bottom of the bus which can carry more than 40 passengers and can pick up max. 60kW. To remove parasitic component and to transfer maximum power between them resonant circuit topology is applied to the primary and secondary sides. The EMF level is below 62.5mG at 1.75m from the center of the road to meet the regulation. Several effective ways of reducing EMF levels have been developed. In addition, effective ways to solve problems related high frequency power cables buried in ground and it's proof from soil have been studied also. This development shows that the IPS system is capable of supplying enough power to the pick-up of OLEV and can reduce battery size, weight and cost, which means the IPS with OLEV is one of the best candidate for EV.

• 한국정보과학회논문지:정보통신
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• 제31권1호
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• pp.37-52
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• 2004

브로드 캐스트(Broadcast)는 하나 또는 여러 개의 채널을 이용해서 다수의 이동 단말기들이 빈번하게 필요로 하는 데이타를 효과적으로 전송하기 위한 방법 중에 하나이다. 이동 단말기의 배터리 소모량을 최소화하기 위해서, 브로드캐스트 되는 데이타를 위한 접근시간을 최소화하는 것이 가장 중요한 문제로 대두되었다. 이런 관점에서 브로드캐스트 되는 데이타에 인덱스를 제공함으로써 데이타 접근시간을 최소화하는데 초점을 맞춘 연구들이 수행되어 왔다. 이 논문에서는 멀티채널(Multi Channels) 환경에서의 효과적인 브로드캐스트(Broadcast)를 위한 인덱스 할당 방법에 대해 연구하였다. 지금까지 제안된 방법들은 브로드캐스트 되는 데이타와 인덱스의 크기가 같아야 한다는 가정을 필요로 하거나 사용되는 인덱스 트리의 깊이와 같은 수의 채널이 주어지지 않을 경우 본래의 성능을 보이지 못하는 단점을 가지고 있다. 앞에서 언급한 두 가지 문제점은 브로드캐스트 데이타에 대해서 평균 접근시간의 증가를 초래하게 된다. 이러한 문제점을 극복하기 위하여 본 논문에서는, 채널을 데이타와 인덱스 채널로 분리한 후, 빈도수가 높은 데이타와 해당 데이타에 대한 트리 구조 인덱스를 보다 많이 브로드캐스트 함으로써 브로드캐스트 데이타에 대한 평균 접근 시간을 최소화하는 방법을 제안한다. 본 논문에서는 제안하는 방법의 실험적 및 이론적인 성능 분석을 이와 비슷한 다른 방법들과 비교함으로써 수행한다. 제시한 방안의 성능 분석은 현존하는 다른 방법과 비교해서 브로드캐스트 데이타에 대해서 현저한 평균 접근 시간 감소를 보여준다.

• 전력전자학회논문지
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• 제12권6호
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• pp.456-464
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• 2007

본 논문에서는 새로운 연료전지용 3상 전류형 능동클램프 DC-DC 컨버터를 제안한다. 전류형 컨버터 구조에 능동클램프 회로를 채용하여 과도기에 발생하는 서지전압을 저감하였고 모든 스위치에서 영전압 스위칭을 하며, 그 장점으로 : 연속적인 입력전류, 전압 오버슈트 제거, 영전압 턴 온 스위칭, 고주파 변압기 1차/2차 측에 부가적인 스너버 회로의 필요성 제거, 소프트 스위칭에 의한 저속 다이오드 적용 등이 있다. 더구나 대용량 발전 시스템에 적합하도록 전류형 컨버터 구조와 3상 전력변환 회로를 결합하였다. 3상 전력변환 적용의 장점은 : 입력전류 및 출력전압 주파수의 3배 증가, 스위치에 흐르는 RMS 전류 저감, 필터소자 용량 및 부피 감소, 고주파 변압기 이용률 증가, 단순화된 전력회로에 따른 전체 크기 축소 및 신뢰성 향상 등이 있다. 제안하는 3상 전류형 능동 클램프 DC-DC 컨버터는 이러한 장점들 때문에 발전용 연료전지 시스템의 승압형 DC-DC 컨버터에 적합하며 대용량 태양전지 발전 시스템 및 배터리 충전기 등에도 적용할 수 있다. 새로운 3상 DC-DC 컨버터와 3상 PWM 알고리즘을 제안하며, 시뮬레이션과 프로토타입의 제작 및 실험을 통하여 그 성능을 평가 및 확인하였다.

• 한국환경과학회지
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• 제19권11호
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• pp.1397-1405
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• 2010

Mass mortalities of cultivated organisms have occurred frequently in Korean coastal waters causing enormous losses to cultivating industry. The preventive measures require continuous observation of farm environment and real-time provision of data. However, line hanging aquaculture farm are generally located far from monitoring buoys and has limitations on installation of heavy equipments. Substituting battery pack for solar panels and miniaturizing size of buoy, newly developed system can be attached to long line hanging aquaculture farm. This system could deliver measured data to users in real-time and contribute to damage mitigation and prevention from mass mortalities as well as finding their causes. The system was installed off Gijang and Yeongdeck in Korea, measuring and transmitting seawater temperature at the sea surface every 30 minutes. Short term variation of seawater temperature, less than one day, in Gijang from June to July 2009 corresponded tidal period of about 12 hours and long term variation seemed to be caused by cold water southeast coast of Korea, particularly northeast of Gijang. Seawater temperature differences between Gijang station and the other station that is about 500 m away from Gijang station were $1^{\circ}C$ on average. This fact indicates that it is need to be pay attention to use substitute data even if it is close to the station. Daily range of seawater temperature, one of crucial information to aquaculture, can be obtained from this system because temperature were measured every 30 minutes. Averages of daily range of temperature off Gijang and Yeongdeok during each observation periods were about $2.9^{\circ}C$ and $4.7^{\circ}C$ respectively. Dominant period of seawater temperature variation off Yeongdeok was one day with the lowest peak at 5 a.m. and the highest one at 5 p.m. generally, resulting from solar radiation.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1261-1262
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• 2008

Laser-based crystallization techniques are ideally-suited for forming high-quality crystalline Si films on active-matrix display backplanes, because the highly-localized energy deposition allows for transformation of the as-deposited a-Si without damaging high-temperature-intolerant glass and plastic substrates. However, certain significant and non-trivial attributes must be satisfied for a particular method and implementation to be considered manufacturing-worthy. The crystallization process step must yield a Si microstructure that permits fabrication of thin-film transistors with sufficient uniformity and performance for the intended application and, the realization and implementation of the method must meet specific requirements of viability, robustness and economy in order to be accepted in mass production environments. In recent years, Low Temperature Polycrystalline Silicon (LTPS) has demonstrated its advantages through successful implementation in the application spaces that include highly-integrated active-matrix liquid-crystal displays (AMLCDs), cost competitive AMLCDs, and most recently, active-matrix organic light-emitting diode displays (AMOLEDs). In the mobile display market segment, LTPS continues to gain market share, as consumers demand mobile devices with higher display performance, longer battery life and reduced form factor. LTPS-based mobile displays have clearly demonstrated significant advantages in this regard. While the benefits of LTPS for mobile phones are well recognized, other mobile electronic applications such as portable multimedia players, tablet computers, ultra-mobile personal computers and notebook computers also stand to benefit from the performance and potential cost advantages offered by LTPS. Recently, significant efforts have been made to enable robust and cost-effective LTPS backplane manufacturing for AMOLED displays. The majority of the technical focus has been placed on ensuring the formation of extremely uniform poly-Si films. Although current commercially available AMOLED displays are aimed primarily at mobile applications, it is expected that continued development of the technology will soon lead to larger display sizes. Since LTPS backplanes are essentially required for AMOLED displays, LTPS manufacturing technology must be ready to scale the high degree of uniformity beyond the small and medium displays sizes. It is imperative for the manufacturers of LTPS crystallization equipment to ensure that the widespread adoption of the technology is not hindered by limitations of performance, uniformity or display size. In our presentation, we plan to present the state of the art in light sources and beam delivery systems used in high-volume manufacturing laser crystallization equipment. We will show that excimer-laser-based crystallization technologies are currently meeting the stringent requirements of AMOLED display fabrication, and are well positioned to meet the future demands for manufacturing these displays as well.

• 전기화학회지
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• 제11권4호
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• pp.268-272
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• 2008

본 연구에서는 $LiFePO_4$의 입자크기를 조절함으로써 우수한 전극특성을 나타낼 수 있도록 최적의 입자크기($50{\sim}100\;nm$)를 가지는 $LiFePO_4$ 양극 활물질을 전기방사법을 이용하여 합성하였다. XRD 분석결과 FeP, $Fe_2P$ 등의 불순물이 존재하지 않는 Pnma의 공간군을 가지는 잘 발달된 사방정 구조의 $LiFePO_4$가 합성됨을 확인하였으며, SEM 분석을 통하여 시료의 입자형태 및 크기를 관찰하였다. $0.1\;mA/cm^2$의 전류밀도와 $2.8{\sim}4.0\;V$의 전위영역에서 충 방전 테스트 수행시 135 mAh/g의 초기 방전용량을 나타내었으며, 50 싸이클 후에도 99.9% 이상의 용량 보존율을 보이는 우수한 싸이클 특성을 나타내었다.

• Asian-Australasian Journal of Animal Sciences
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• 제25권11호
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• pp.1605-1610
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• 2012

Two experiments were conducted to study the effects of red pepper (Capsicum frutescens) powder or red pepper pigment on the performance and egg yolk color of laying hens. In Exp. 1, 210, thirty-wk old, Hy-line Brown laying hens were fed one of seven diets containing 0.3, 0.6, 1.2, 2.0, 4.8 or 9.6 ppm red pepper pigment or 0.3 ppm carophyll red. Each diet was fed to three replicate batteries of hens with each battery consisting of a row of five cages of hens with two hens per cage (n = 3). In Exp. 2, 180, thirty-wk old, Hyline Brown laying hens, housed similarly to those in Exp. 1, were fed an unsupplemented basal diet as well as treatments in which the basal diet was supplemented with 0.8% red pepper powder processed in a laboratory blender to an average particle size of $300{\mu}m$, 0.8% red pepper powder processed as a super fine powder with a vibrational mill ($44{\mu}m$) and finally 0.8% red pepper powder processed as a super fine powder with a vibrational mill but mixed with 5% $Na_2CO_3$ either before or after grinding. A diet supplemented with 0.3 ppm carophyll red pigment was also included (n = 3). In both experiments, hens were fed the red pepper powder or pigment for 14 days. After feeding of the powder or pigment was terminated, all hens were fed the basal diet for eight more days to determine if the dietary treatments had any residual effects. In Exp. 1, there were no differences in egg-laying performance, feed consumption or feed conversion ratio due to inclusion of red pepper pigment in the diet. Average egg weight was higher (p<0.05) for birds fed 1.2, 2.4 or 9.6 ppm red pepper pigment than for birds fed the diet containing 0.3 ppm red pepper pigment. On d 14, egg color scores increased linearly as the level of red pepper pigment in the diet increased. In Exp. 2, feeding red pepper powder did not affect egg-laying performance, feed consumption or feed conversion ratio (p>0.05). However, compared with the control group, supplementation with all of the red pepper powder treatments increased egg weight (p<0.05). All the red pepper powder treatments also increased (p<0.05) the yolk color score compared with the control. The results of the present study suggest that both red pepper powder and pigment are effective feed additives for improving egg yolk color for laying hens.