• 대한의용생체공학회:의공학회지
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• 제32권2호
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• pp.177-184
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• 2011

In this study, the system for application of the bone stimulation was implemented using high frequency and low strain method. The whole system consists of the high frequency and low strain vibration stimulation system 177 for stimulating bone, LVDT sensor, and wireless sensor based on tri-axial accelerometer. To evaluate the usefulness of the system, the frequencies and accelerations from function generator were applied to the vibration stimulation system. The range of frequency was 17 Hz, 30 Hz, 45 Hz, 50 Hz and the range of acceleration was set 0.3 g, 0.6 g, 1g, and 2 g. The measured frequencies and acceleration using LVDT (linear variable difference transformer) sensor and 3-axial accelerometer were estimated and compared. The range of frequencies average difference was from 0.0 to 0.004 Hz. As the standard deviation of frequencies estimated by LVDT sensor and accelerometer was below 0.03 Hz and the output frequencies of function generator were similar: Also the results of t-test were satisfied with conditions of p > 0.05. And the acquired frequencies and acceleration from vibration measuring device module were estimated and analyzed. As the mean of accelerations was similar to the acceleration applied from function generator. And the standard deviation of acceleration estimated from vibration measuring device module was ranged from 0.019 g to 0.038 g. Also the results of t-test were satisfied with conditions of p > 0.05. Therefore, these results were airy similar to the acceleration applied from function generator. As a result, the usefulness of the system was confirmed. n a further study, clinical experiment will be carried out with the authorization of IRB (institutional review board) so that appropriate frequency and strain would be investigated in clinical field.

• 한국전자통신학회논문지
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• 제13권4호
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• pp.819-826
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• 2018

일반화된 해밍무게는 선형부호의 중요한 파라미터의 하나로써 암호시스템에 적용할 때 부호의 성능을 결정한다. 그리고 격자도를 이용하여 블록부호를 연판정으로 복호할 때 구현에 필요한 상태복잡도를 평가하는 척도가 되기도 함으로써 그 중요성이 한층 부각되고 있다. 특별히 삼항다항식을 기반으로 하는 유한체 상의 비트-병렬 곱셈기에 대한 연구가 진행되어왔다. 셀룰라오토마타(Cellular Automata, 이하 CA)는 국소적 상호작용에 의해 상태가 동시에 업데이트되는 성질이 있어서 LFSR보다 랜덤성이 우수하다. 본 논문에서는 효과적인 암호시스템 설계에 있어 중요한 요소 중 하나인 의사난수열 생성기의 효과적 합성에 관하여 다룬다. 먼저 간단한 90/150 전이규칙 블록의 특성 다항식의 성질을 분석하고, 이 규칙블록을 이용하여 삼항다항식 $x^2^n+x^{2^n-1}+1$($n{\geq}2$)에 대응하는 가역 90/150 CA와 $2^n$차 최대무게다항식에 대응하는 90/150 가역 CA(RCA)의 합성알고리즘을 제안한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.425-425
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• 2008

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3mW is obtained at the temperature difference of 45K. We provide a promising approach for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which can employ nanostructures for high thermoelectric properties.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.443-447
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• 2009

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_{2}Te_{3}$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $5{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_{2}Te_{3}$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_{2}Te_{3}$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3 ${\mu}m$ is obtained at the temperature difference of 45 K.

• 대한수학회보
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• 제55권6호
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• pp.1627-1638
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• 2018

In this paper, we study an special type of cyclic codes called skew cyclic codes over the ring ${\mathbb{F}}_p+v{\mathbb{F}}_p+v^2{\mathbb{F}}_p$, where p is a prime number. This set of codes are the result of module (or ring) structure of the skew polynomial ring (${\mathbb{F}}_p+v{\mathbb{F}}_p+v^2{\mathbb{F}}_p$)[$x;{\theta}$] where $v^3=1$ and ${\theta}$ is an ${\mathbb{F}}_p$-automorphism such that ${\theta}(v)=v^2$. We show that when n is even, these codes are either principal or generated by two elements. The generator and parity check matrix are proposed. Some examples of linear codes with optimum Hamming distance are also provided.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.219-222
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• 2013

Alloy 690 has been selected as a steam generator tubing material for SMART owing to a near immunity to primary water stress corrosion cracking. The steam generators of SMART are faced with a neutron flux due to the integrated arrangement inside a reactor vessel, and thus it is important to know the irradiation effects of the thermal conductivity of Alloy 690. Alloy 690 was irradiated at HANARO to fluences of (0.7-28) ${\times}10^{19}n/cm^2$ (E>0.1MeV) at $250^{\circ}C$, and its thermal conductivity was measured using the laser-flash equipment in the IMEF. The thermal conductivity of Alloy 690 was dependent on temperature, and it was a good fit to the Smith-Palmer equation, which modified the Wiedemann-Franz law. The irradiation at $250^{\circ}C$ did not degrade the thermal conductivity of Alloy 690, and even showed a small increase (1%) at fluences of (0.7~28) ${\times}10^{19}n/cm^2$ (E>0.1MeV).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.142-142
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• 2007

Micro thermoelectric generator has been attractive for the alternative power source to operate the wireless sensor node. In this paper, we designed the column-type micro thermoelectric device and their device characteristics were measured. n-type Bi2Te3 and p-type BiSbTe3 thermoelectric thin films were grown on (001) GaAs substrates by metal organic chemical vapour deposition (MOCVD) and they were pattemed. The height of thermoelectric film were controlled by the deposition time, temperature and MO-x gas pressure. Seebeck coefficient was measured at room temperature and hole concentration and electrical resistivity of thermoelectric film were also characterized.

• Journal of Korean Neurosurgical Society
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• 제58권4호
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• pp.368-372
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• 2015

Objective : The occurrence of acute cerebral infection following deep brain stimulation (DBS) is currently being reported with elevation of C-reactive protein (CRP) level. The aim of the present study was to establish normal range of the magnitude and time-course of CRP increases following routine DBS procedures in the absence of clinical and laboratory signs of infection. Methods : A retrospective evaluation of serial changes of plasma CRP levels in 46 patients undergoing bilateral, two-staged DBS was performed. Because DBS was performed as a two-staged procedure involving; implantation of lead and internal pulse generator (IPG), CRP was measured preoperatively and postoperatively every 2 days until normalization of CRP (post-lead implantation day 2 and 4, post-IPG implantation day 2, 4, and 6). Results : Compared with preoperative CRP levels ($0.12{\pm}0.17mg/dL$, n=46), mean CRP levels were significantly elevated after lead insertion day 2 and 4 ($1.68{\pm}1.83mg/dL$, n=46 and $0.76{\pm}0.38mg/dL$, n=16, respectively, p<0.001). The mean CRP levels at post-lead implantation day 2 were further elevated at post-IPG implantation day 2 ($3.41{\pm}2.56mg/dL$, n=46, respectively, p<0.01). This elevation in post-IPG day 2 rapidly declined in day 4 ($1.24{\pm}1.29mg/dL$, n=46, p<0.05) and normalized to preoperative value at day 6 ($0.42{\pm}0.33mg/dL$, n=46, p>0.05). Mean CRP levels after IPG implantation were significantly higher in patients whose IPGs were implanted at post-lead day 3 than those at post-lead day 5-6 ($3.99{\pm}2.80mg/dL$, n=30, and $2.31{\pm}1.56mg/dL$, n=16, respectively, p<0.05). However, there was no difference in post-IPG day 2 and 4 between them (p>0.05). Conclusion : The mean postoperative CRP levels were highest on post-IPG insertion day 2 and decreased rapidly, returning to the normal range on post-IPG implantation day 6. The duration of post-lead implantation period influenced the magnitude of CRP elevation at post-IPG insertion day 2. Information about the normal response of CRP following DBS could help to avoid unnecessary diagnostic and therapeutic efforts.

• 한국분말재료학회지
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• 제22권5호
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• pp.321-325
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• 2015

The triboelectric property of a material is important to improve an efficiency of triboelectric generator (TEG) in energy harvesting from an ambient energy. In this study, we have studied the TEG property of a semiconducting $SnO_2$ which has yet to be explored so far. As a counter triboelectric material, PET and glass are used. Vertical contact mode is utilized to evaluate the TEG efficiency. $SnO_2$ thin film is deposited by atomic layer deposition on bare Si wafer for various thicknesses from 5.2 nm to 34.6 nm, where the TEG output is increased from 13.9V to 73.5V. Triboelectric series are determined by comparing the polarity of output voltage of 2 samples among $SnO_2$, PET, and glass. In conclusion, $SnO_2$, as an intrinsic n-type material, has the most strong tendency to be positive side to lose the electron and PET has the most strong tendency to be negative side to get the electron, and glass to be between them. Therefore, the $SnO_2$-PET combination shows the highest TEG efficiency.

• 한국조명전기설비학회지:조명전기설비
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• 제9권2호
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• pp.123-123
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• 1995

본 논문은 대전원 탈락 사고시 계통의 지나친 주파수하락을 방지하기 위하여 주파수하락의 초기변화율을 근거로 하여 적정부하를 차단할 수 있도록 저주파수계전기의 합리적인 정정방법을 제시한다. 본 연구에서의 부하차단 전략은, 주파수가 59.5[Hz]에 이를 때 부하차단 제1단을 일으키고 제1,2단에의 크기가 주파수하락의 초기변화율을 근거하여 주어진 계통외란의 크기인 총 정태부하 차단량의 1/2이되도록 정정하였다. 그 결과 새로 제안한 방법이 주파수 회복특성에 있어서 종래의 방법보다 더 효과적임을 알 수 있다.