• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.297.2-297.2
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• 2016

Photoacoustic generation of ultrasound is an effective approach for development of high-frequency and high-amplitude ultrasound transmitters. This requires an efficient energy converter from optical input to acoustic output. For such photoacoustic conversion, various light-absorbing materials have been used such as metallic coating, dye-doped polymer composite, and nanostructure composite. These transmitters absorb laser pulses with 5-10 ns widths for generation of tens-of-MHz frequency ultrasound. The short optical pulse leads to rapid heating of the irradiated region and therefore fast thermal expansion before significant heat diffusion occurs to the surrounding. In this purpose, nanocomposite thin films containing gold nanoparticles, carbon nanotubes (CNTs), or carbon nanofibers have been recently proposed for high optical absorption, efficient thermoacosutic transfer, and mechanical robustness. These properties are necessary to produce a high-amplitude ultrasonic output under a low-energy optical input. Here, we investigate carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite transmitters and their nanostructure-originated characteristics enabling extraordinary energy conversion. We explain a thermoelastic energy conversion mechanism within the nanocomposite and examine nanostructures by using a scanning electron microscopy. Then, we measure laser-induced damage threshold of the transmitters against pulsed laser ablation. Particularly, laser-induced damage threshold has been largely overlooked so far in the development of photoacoustic transmitters. Higher damage threshold means that transmitters can withstand optical irradiation with higher laser energy and produce higher pressure output proportional to such optical input. We discuss an optimal design of CNT-PDMS composite transmitter for high-amplitude pressure generation (e.g. focused ultrasound transmitter) useful for therapeutic applications. It is fabricated using a focal structure (spherically concave substrate) that is coated with a CNT-PDMS composite layer. We also introduce some application examples of the high-amplitude focused transmitter based on the CNT-PDMS composite film.

• 융합보안논문지
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• 제11권4호
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• pp.37-42
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• 2011

본 논문에서는 유비쿼터스 도시(Ubiquitous City, u-City) 건설시 고려해야 하는 정보보안의 설계 방안을 제시한다. 이를 위하여 먼저, u-City에 대한 정의, 개념 및 주요 유비쿼터스 서비스를 정리한다. 그리고 유비쿼터스 서비스를 제공하기 위해 필요한 u-City 통합운영센터의 주요 구성요소 및 기능을 제시하고, 정보 수집, 가공, 교환시 개인정보의 보호를 위해 준수해야 하는 관련 법률을 분석하며 통합운영센터에서의 네트워크 보안 설계 방안을 제시한다. 개인정보 보호를 위하여 통합운영센터에서는 Router/Switch, Firewall/VPN(Virtual Private Network),IPS(Intrusion Prevention System)의 3단계 보안을 적용해야 하며, 1단계에서는 비정상적 패킷의 유입 차단, 2단계에서는 서비스별 접근 통제, 3단계에서는 실시간 네트워크 침입 감시 기능을 수행한다. 끝으로, 제시된 3단계 보안 방법론의 검증을 위하여 실제 적용 사례를 제시함으로서 u-City에서의 효율적인 개인 정보보호 방안을 제시한다.

• 한국콘텐츠학회논문지
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• 제17권6호
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• pp.632-642
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• 2017

본 연구의 목적은 수술 후 24시간 동안 수술 후 오심과 구토의 영향요인을 파악하고자 시도되었다. 연구 대상은 G시에 소재한 일 대학병원 일반외과, 신경외과, 정형외과, 산부인과, 이비인후과 수술을 받은 332명의 환자였다. 자료수집은 2014년 12월부터 2015년 12월까지 이루어졌으며, 자료는 t-test, $x^2$-test와 logistic regression analysis를 이용하여 분석하였다. 대상자 중 수술 후 오심과 구토가 발생한 유발군은 41.0%였다. 다변량 분석으로 분석한 결과, 흡연을 하지 않는 경우(p=.009), 멀미 과거력이 있는 경우(p=.016), 수술 후 오심과 구토 과거력이 있는 경우(p=.006), 수술 후 통증(p=.001)이 수술 후 오심과 구토 발생의 영향요인으로 나타났다. 따라서 비흡연, 멀미 과거력, 수술 후 오심과 구토 과거력이 있는 경우 수술전부터 집중적인 관리가 필요하며 수술 후 통증에 대한 적극적인 중재가 필요하다.

• 대한족부족관절학회지
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• 제5권2호
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• pp.120-128
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• 2001

Purpose: This study was undertaken to review the precise morphological patter'ns of polydactyly of the foot and to evaluate outcomes of surgical interventions. Materials and Methods: The records of patients who had polydactyly of foot from 1983 to 2000 were reviewed retrospectively. 29 duplicated toes(24 patients) were analyzed. All cases were evaluated and classified with Temtamy and McKusick's axial pattern, Watanabe's morphologic pattern and level of duplication. Clinical evaluation was performed according to Phelps and Grogan's. Mean age at surgery was 5.7 years(range: 10 months$\sim21$ years). All the patients were subsequently evaluated during mean 17 months(range: 13 months-$\sim5$ years). Results: Preaxial polydactyly was seen in 3 cases, central polydactyly in 3 cases, postaxial polydactyly in 22 cases and remaining 1 case was multiple my involvement. Only 2 patients have familial history and the most common associated anomaly was hand deformity(20.8%). Clinical results were excellent in 14 cases, good in 5 cases, poor in one. 17 patients(70%) were operated before 6 years olds and they had better results than those of who were operated after 6 years olds. Conclusion: The Method of surgical correction for the polydactyly should be individualized by its morphological pattern because the purpose of operation was to give comfort in wearing shoes and patient's psychological relief. This study showed that polydactyly of the foot could be corrected surgically with good results in most cases, and the better results would be achieved if the operation is performed before preschool age according to its individualized pattern of duplication.

• 한국군사과학기술학회지
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• 제16권3호
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• pp.322-331
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• 2013

Wireless Mesh Networks(WMNs) is generally composed of radio nodes in the mesh topology. WMNs consists of mesh client, mesh router and gateway connected to a wired network. Each client and router relay messages to the gateway for communication. WMNs is widely used recently in many areas can provide extended coverage based on multi-hop communication and ubiquitous communication at any time and any location. However the competition and collision between each node to transmit data is inevitable when the same channel is used for transmission. The transmission opportunities and the throughput of nodes located far from gateway decrease more if the communication channel is accessed based on competitive CSMA/CA scheme using DCF(Distributed Coordination Function) provided by IEEE 802.11 MAC. In this paper, we improve the performance of the TCP fairness and throughput of the nodes with more than 2 hops by applying various algorithms for controlling contention window values. Also, we evaluate the performance using ns-2 simulator, According to the results, proposed scheme can enhance the fairness characteristic of each node irrespective of data to the gateway.

• 정보처리학회논문지C
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• 제12C권4호
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• pp.535-542
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• 2005

본 논문은 새로운 대체경로 확보 방안을 통하여 라우팅 성능을 개선하는 요구형 애드학 라우팅 프로토콜인 Node Density Based Routing(NDBR)을 제안한다. 모바일 노드들의 이동이나 전력 고갈 등으로 인해 애드학 망의 연결은 장애를 일으킬 가능성이 매우 높기 때문에 발신지에서 목적지까지의 연결 설정 시 대체경로를 확보해 두는 것이 중요하다. NDBR은 목적지까지의 대체경로들을 확보하기 위해 상대적으로 더 많은 이웃 노드들을 갖는 중간 노드들로 구성되는 연결 설정을 목표로 하며 이를 위해 노드 밀집도라는 새로운 경로선택기준을 도입한다. NDBR은 경로 장애 발생 시 발신지에 의한 경로재탐색 절차 없이 목적지에 대한 도달성을 향상시킴으로써 경로장애의 영향을 국소화시키고, 제어 트래픽에 의한 오버헤드를 줄이며, 경로재설정 시간을 감소시킬 수 있다 본 논문에서는 노드 밀집도를 이용하여 대체경로를 포함하는 경로설정 절차와 경로 상의 중간 노드에서 대체경로 정보를 유지하여 활용하는 방법에 대해 기술하고 시뮬레이션을 통한 기존 프로토콜과의 비교를 통해 라우팅 성능이 개선됨을 보였다.

• 한국컴퓨터산업학회논문지
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• 제2권3호
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• pp.363-368
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• 2001

이동통신(Mobile Telecommunication), X선 발생장치, 오존발생기, 레이저시스템 등에 사용되는 임펄스의 지속시간(pulse duration)은 충분히 짧고 빠른 상승률을 갖는 임펄스 전압을 발생시킬 수 있는 펄스발생장치(Pulse Generator)가 필요하다. 펄스발생장치 설계시 회로정수, 전력용 스위치는 임펄스 특성을 직접적으로 결정하게 된다. 펄스발생장치는 출력에너지가 순간적으로 부하에 전달될 때 최소의 손실로 전류지속시간 동안 안정성을 갖고 전류차단시 소호특성이 우수한 전력용 스위치가 요구된다. 펄스에너지 효율은 펄스 상승시간(rising time), 첨두치(peak value), 지속시간(pulse duration), 부하와의 임피던스 매칭(impedance matching) 등에 따라 민감하게 반응한다. 또한, 짧은 펄스지속시간과 높은 첨두치의 펄스에너지를 얻기 위해서는 펄스발생장치의 크기 및 경제성을 고려하지 않을 수 없다. 본 연구에서는 수$\mu$s의 펄스지속시간(pulse duration), 수 l00ns의 상승시간(rising time) 및 수 10kV의 첨두값(peak value), 수 10~100회의 반복율 갖는 안정적인 임펄스 형성을 위해 소형 펄스트랜스 2개를 조합한 cascading 방식을 적용하여 컴팩트(compact)한 펄스발생장치(pulse generator)를 구성하여 부하에 직접 제작한 임펄스를 인가한 결과 우수한 효과를 거둘 수 있었고, 그 적용에 대한 연구는 차후에 진행하고자 한다.

• 사상체질의학회지
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• 제14권1호
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• pp.26-33
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• 2002

1. Purpose The purpose of this article was to find the change of Dong-mu's conceptions about constitutional disease through comparing with ${\ulcorner}$Sasang-Yihak-chobonguen${\lrcorner}$, ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ written in 1894(Old edition) and ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ published in 1901(In Edition) 2. Methods Comparing with ${\ulcorner}$Sasang-Yihak-chobonguen${\lrcorner}$, ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ written in 1894(Old edition) and ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ published in 1901(In Edition) we found the change of Dong-mu's conceptio ns about constitutional disease 3. Result 1) In ${\ulcorner}$Sasang-Yihak-chobonguen${\lrcorner}$, diseases were classified 'Oi-Gam(外感)‘, ’Nae-sang(內傷)‘, ’Ok-roi(牢獄)‘. ’Wi-gyoung(危傾)‘. In ${\ulcorner}$Sasang-Yihak-chobonguen${\lrcorner}$ ordinary symptoms was more impotant than disease, and good life style was emplasized for health 2) In ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ written in 1894(Old edition), diseases were classified 'Oi-Gam(外感)‘, ’Nae-sang(內傷)‘. siseases from exterior causes was classified into 'Oi-gam-noi-chu-byoung(外傷腦?頁病)’, and diseases from interior causes was classified into 'Nae-sang-wi-wan-byoung(內觸胃脘病).‘ Herbal medication yet was't used by Disease 3) In ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ published in 1901(In Edition), diseases was classified not by causes of disease but by mechanism and symptom of disease, so into Exterior-cold disease' and 'Interior-hot disease'. Herbal medication was used by pattern of Disease. 4) Conception of constitutional diseases was gradualy complished through edition.

• 한국학교보건학회지
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• 제21권1호
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• pp.33-41
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• 2008

Purpose : The purpose of this study was to provide the basic data for p lanning oral health education in elementary schol. Methods conducted using a postal, self-administered questionnaire. A questionnaire containing 19 questions about oral health education which was provided by health teachers in elementary schol was used for data colle ction. Total response rate was 64.3% (119 out of 185). Results : Oral health education except one through textbooks was conduc of which taught oral health themselves. The contents of oral he alth education through special clas was mainly focusing on the tothbrushing method, dental caries, and the use of fluo ride. Acording to the grades clasified by the level of education, the order was the 3rd, 1st, and 2nd grade, which mea ns that the lower grades got more training than the h was acquired through the internet (72.2%), health-related organizations or academies (51.5%). Also, materi als for oral health education were obtained from health-related organizations or academies (67%), self-productio n (49.5%). According to the data during the past 5 years it was found that 13.4% health teachers had oral health-related that more traing neded to be conducted from 89.7% health tea chers. The most dificult problem in oral health education were insufficient time (56.7%). Conclusion : For effective oral health education, there needs a developmen t of targeted goal to achieve a systemic oral health education for each grades as wel as a ned for as health teachers to eficiently acquire knowledge and materials for oral health education, it is necessary to hold regular workshops for health teachers, and develop and distribute appro priate educational materials.

• Journal of Magnetics
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• 제15권3호
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• pp.103-107
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• 2010

We investigated spin-polarized current switching of Pac-man type II (PM-II) nanoelements in Pac-man shaped nanoscale spin-valves (Co/Cu/Py) using micromagnetic simulations. The effects of slot angle and antiferromagnetic (AFM) layer were simulated to obtain optimum switching in less than 2 ns. At a critical slot angle of $105^{\circ}$, the lowest current density for anti-parallel to parallel (AP-P) switching was observed due to no vortex or antivortex formation during the magnetic reversal process. All other slot angles for AP-P formed a vortex or antivortex during the magnetization reversal process. Additionally, a vortex or anti-vortex formed for all slot angles for parallel to anti-parallel (P-AP) switching. The addition of an AFM layer caused the current density to decrease significantly for AP-P and P-AP at slot angles less than $90^{\circ}$. However, at slot angles greater than $90^{\circ}$, the current density tended to decrease by less amounts or actually increased slightly as shape anisotropy became more dominant. This allowed ultra-fast switching with 5.05 and $5.65{\times}10^8\;A/cm^2$ current densities for AP-P and P-AP, respectively, at a slot angle of $105^{\circ}$.