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이동현,이승환,이성갑,이규탁,이영희,Lee, Dong-Hyun,Lee, Seung-Hwan,Lee, Sung-Gap,Lee, Ku-Tak,Lee, Young-Hie 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.7
We studied sintering temperature to enhance the piezoelectric properties of $0.98(Na_{0.5}K_{0.5})NbO_3-0.02Li(Sb_{0.17}Ta_{0.83})O_3$+0.01wt%ZnO (hereafter NKN-LST+ZnO) lead free piezoelectric ceramics. The synthesis and sintering method were the conventional solid state reaction method and sintering was executed at $1,080\sim1,120^{\circ}C$. We found that NKN-LST+ZnO ceramics at optimal sintering temperature showed the improved piezoelectric properties at the optimal sintering temperature. The NKN-LST+ZnO ceramics show good performance with piezoelectric constant $d_{33}$= 153 pC/N sintered at $1,090^{\circ}C$. The results reveal that NKN-LST+ZnO ceramics are promising candidate materials for lead-free piezoelectric application.
이동현,김지은,송채빈,이현주,송원영,이태준,이상훈,태기식,Lee, D.H.,Kim, J.E.,Song, C.B.,Lee, H.J.,Song, W.Y.,Lee, T.J.,Lee, S.H.,Tae, Ki-Sik 대한의용생체공학회 2016 의공학회지 Vol.37 No.3
Sexual addiction is accompanied with anxiety, psychological and physical dependence. Also, sexual addict want to make their presence through sexual adventures and seem sexually obsessed. In this study, we examined the changes of brain activity related to sexual addiction by utilizing the developed multi-sensory therapy after 4-weeks sex offender treatment program. We analyzed the electroencephalogram (EEG) activity changes in the subjects and regions of brain. As a result, the theta wave significantly increased after treatment than before (p < 0.001). The absolute alpha wave was increased whereas the relative alpha waves were decrease significantly (p < 0.001). The results could conclude that multi-sensory therapy on sex offender shows more stable status against sexual stimulations. Moreover, the reduction of the relative alpha waves in parietal lobe of sex offender is correlated to the less attention on sexual stimulations. The multi-sensory therapy not only provides a neurobiological explanation, but also can be used for clinical implications, i.e. prevention and treatments, for sex addiction.
이종입자 강화 SiC/Al7075 금속복합재료의 압축특성 및 마모특성 연구
이동현,조승찬,김양도,이상관,이상복,조일국,Lee, Donghyun,Cho, Seungchan,Kim, Yangdo,Lee, Sang-Kwan,Lee, Sang-Bok,Jo, Ilguk 한국복합재료학회 2017 Composites research Vol.30 No.5
본 연구에서는 액상가압공정을 통해 고체적율의 SiC 입자가 균일 분산된 알루미늄 금속복합재료를 제조하고, 미세조직, 기계적 특성 및 내마모 특성에 대해 분석하였다. 입자크기가 다른 이종 SiC 입자가 약 60 vol.% 이상의 체적율로 균일하게 분산된 SiC/Al7075 복합재료는 단일 SiC 입자로 강화된 복합재료에 비해 체적율이 약 12% 이상 높았으며 압축강도가 200 MPa 이상 증가하였다. 내마모시험 결과 이종 SiC 입자 금속복합재료의 경우 마모너비와 깊이가 각각 $285.1{\mu}m$, $0.45{\mu}m$이며, 마찰계수는 0.16으로 내마모 특성이 가장 우수하였다. In this study, we have investigated microstructure, mechanical properties and wear characteristic of aluminum metal matrix composites with a high volume fraction and uniformly dispersed SiC particles which produced by a liquid pressing process. The volume fraction of bimodal SiC/Al7075 composite was 12% higher than that of the monomodal SiC/Al7075 composite and a compressive strength is increased about 200 MPa. As a result of the abrasion test, the wear width and depth of the bimodal SiC/Al7075 composite were $285.1{\mu}m$ and $0.45{\mu}m$, respectively. The coefficient of friction of bimodal SiC/Al7075 was 0.16.
하악 전돌증 환자에서 전산화 단층 촬영을 이용한 하악관의 해부학적 위치에 관한 연구
이동현,김재원,이수연,김재현,안상헌,이상한,장현중,Lee, Dong-Hyun,Kim, Jae-Won,Lee, Su-Youn,Kim, Jae-Hyun,An, Sang-Heon,Lee, Sang-Han,Jang, Hyun-Jung 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.6
Purpose: In this study, we analyzed and compared the anatomical position of the mandibular canal in normal occlusion and mandibular prognathism patients. Patients and Methods: Computed tomography image from 58 patients were divided into normal occlusion group and mandibular prognathism group, and each measurement were taken in the each measuring points(2nd premolar, 1st molar, 2nd molar, 3rd molar, ramus). Measurements were statistically analyzed by student's t-test. Results: BC (Thickness of the buccal cortex) value was 2.3~2.7 mm, CB (Distance from the canal to the lingual aspect of the buccal cortex) value was 1.3~4.3 mm, MC (Diameter of the canal) value was 3.2~3.8 mm, LI (Distance from the canal to the lingual aspect of the lingual cortex) value was 2.0~3.7 mm, TM (Thickness of the total mandible) value was 9.5~12.9 mm and CM (Distance from the canal to the inferior border of the mandible) value was 6.9~17.5 mm. Conclusion: In the comparison between two groups, there was statistically significant difference in CB value of 2nd, 3rd molar between normal occlusion and mandibular prognathism, and other value in the rest of the measuring points didn't show statistically significant difference.
표면 전류 분포를 이용한 T자형 UWB 평면형 모노폴 안테나 해석
이동현,박위상,Lee Dong-Hyun,Park Wee-Sang 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.9
본 논문에서는 T자형의 방사체를 가지는 초광대역 평면형 모노폴 안테나를 제안하고, 방사체와 그라운드 표면에 흐르는 전류 분포를 분석하였다. 측정된 임피던스 대역폭은 VSWR 2 미만 기준으로 3.1${\~}$11 GHz이고, 이는 UWB 대역을 만족한다. 제안된 안테나의 주파수에 따른 표면 전류 분포를 분석하여 제안된 안테나는 두개의 90도 굽은 비대칭적인 다이폴이 대칭으로 놓여 있는 안테나로 동작함을 설명하였다. 이 안테나의 표면 전류 분포가 방사 패턴에 영향을 미치는 양상이 다이폴의 경우와 유사하며, 그라운드 평면의 길이와 너비는 다이폴의 굵기와 길이에 해당한다. 이러한 해석이 다른 일반적인 평면형 모노폴 안테나에도 적용 가능함을 보였다. 끝으로 그라운드 평면의 모서리를 테이퍼링을 하여 공진 주파수를 낮추는 예과 방사체에 역 U자 슬랏을 추가하여 특정 대역을 저지하는 예를 제시하고 이를 표면 전류를 이용하여 설명하였다. We propose a T-shaped UWB printed monopole antenna and investigate the effect of the surface currents of the radiator and ground plane. The measured impedance bandwidth of the antenna covers the range of 3.1 to 11 GHz for a VSWR$\le$2, which satisfies the requirement of the UWB operation. From the analysis of the surface currents, the proposed antenna can be treated as two asymmetric dipoles with the included angle of 90 degrees which lie along z-direction symmetrically. It is observed that the effect of the surface currents on the radiation patterns is similar to that of the corresponding dipole. The length and width of the found plane correspond the radius and length of the dipole respectively. This approach is also valid to general printed monopole antennas. Finally, we included an antenna example having resonance at a lower frequency by tapering the edges of the ground plane and another example having a bandstop characteristic by inserting an inverted-U slot on the radiator, and explain those antennas using the surface currents.
정맥하 진정요법에서 Midazolam 단독 사용과 Midazolam, Fentanyl 또는 Propofol 병용 요법의 비교
이동현,김재원,이상준,김재현,장태화,안상헌,장헌수,Lee, Dong-Hyeon,Kim, Jae-Won,Lee, Sang-Jun,Kim, Jae-Hyeon,Jang, Tae-Hwa,An, Sang-Heon,Jang, Heon-Su 대한치과마취과학회 2008 Journal of Dental Anesthesia and Pain Medicine Vol.8 No.2
Background: The purpose of this study was to compare the use of midazolam only with midazolam with fentanyl or propofol in IV sedation. Methods: 24 cases were divided to midazolam group (M group), midazolam + fentanyl group (MF group), midazolam + propofol group (MP group) and midazolam + fentanyl + propofol group (MFP group). In M group, 2 ml midazolam was injected at first, than at 2 minutes interval 1-2 ml injected continuously depending on the level of sedation. In MP, MFP groups, propofol was injected at the speed of 15-20 ml/hr by infusion pump. In this study, the sedation level was evaluated by using OAA/S scale. In each groups, the recovery time was measured until OAA/S scale score level was 5, and pre and postoperative blood pressure change was measured. Each group's data was statistically analyzed using one-way ANOVA. If significant statistical difference were observed, Dunnet test was performed, and control group was M group. Results: Pre and postoperative blood pressure change were not represent significant statistical difference in 4 groups (P value = 0.679 [systolic], P value = 0.206 [diastolic]). But recovery time were represent significant statistical difference (M group: 35.6, MF group: 32.5, MP group: 17.9, MFP group: 19.6 [P value = 0.002]). The result of Dunnet test on recovery time showed significant statistical difference on MF, MFP group when M group was control group. In MFP group, sedation was increased by using supplemental fentanyl, and postoperative pain control was dominant. Conclusion: To achieve the effect of anxiolysis, analgesia, amnesia effectively, and short recovery time, MFP group is mostly recommended.