Maxwell 방정식의 효율적인 풀이를 위한 경계요소법과 웨이브렛의 결합

김현준,이승걸,오범환,이일항,Kim, Hyun-Jun,Lee, Seung-Gol,O, Beom-Hoan,Lee, El-Hang 대한전자공학회 2002 電子工學會論文誌-CI (Computer and Information) Vol.39 No.6

Maxwell 방정식을 효율적으로 풀기 위해 웨이브렛 행렬 변환(wavelet matrix transformation)과 경계요소법(Boundary Element Method)을 결합하는 방법을 제안하였으며, 2차원 위상변이 마스크(phase- shifting mask) 문제에 적용하였다. 계산 결과를 해석적인 해 및 참고문헌의 결과와 비교함으로써 구현된 모듈의 정확도를 검증하였으며, 제안된 방법이 경계요소법만을 적용한 경우에 비해 연산 시간과 메모리 사용 측면에서 효율적임을 확인하였다. The wavelet transform is combined with the boundary element method (BEM), to solve efficiently the Maxwell's equation and the proposed method is applied to the electromagnetic problem for the analysis of topological effects of phase-shifting masks. The accuracy of the module developed was verified by comparison with both analytic solutions and published results. In addition, it was found that the boundary element method in combination with the wavelet matrix transform would be more efficient than the conventional methods based on the BEM in views of the calculation speed and the usage of computer memory.

Nb를 포함하는 불소산화물에서 구조적 뒤틀림에 따른 에너지 띠 간격의 변화

김현준,김승주,Kim, Hyun-Jun,Kim, Seung-Joo 대한화학회 2007 대한화학회지 Vol.51 No.3

국부적인 결정구조와 에너지 띠 간격 간 상관관계를 고찰하기 위하여 Nb를 포함하는 일련의 불소 산화물에 대하여 결정구조와 자외선-가시광선 확산 반사율 스펙트럼을 비교, 연구하였다. 이 실험에서 다룬 RbSrNb2O6F와 RbCaNb2O6F, RbNb2O5F는 공통적으로, 꼭지점 공유를 하고 있는 NbO5F 팔면체로 구성되어 있 다. 구조적 뒤틀림 정도의 척도로 볼 수 있는 Nb-O(F)-Nb 평균 결합각은 RbSrNb2O6F에서 158.6°, RbCaNb2O6F 에서 149.6° 그리고 RbNb2O5F에서 139.5o이다. 확산 반사율 스펙트럼으로부터 구한 에너지 띠 간격은 Nb-O(F)-Nb 결합각이 감소할수록 증가하는 경향을 보였다. 즉 RbSrNb2O6F, RbCaNb2O6F, RbNb2O5F 각각의 화합물에 대해 서 3.48 eV, 3.75 eV, 4.03 eV 의 값을 나타내었다. 이러한 실험적 결과는 Nb를 포함하는 불소 산화물에서 국 부구조의 변화를 통해 띠 간격을 약 0.6 eV의 범위에서 조절할 수 있음을 의미한다. A comparative study on crystal structures and UV-visible diffuse reflectance spectra for Nb-containing oxyfluorides was performed to probe the relationship between energy band gap and local structure. The oxyfluorides, RbSrNb2O6F, RbCaNb2O6F and RbNb2O5F are commonly composed of the corner-sharing NbO5F octahedra as structural building units. The average Nb-O(F)-Nb bond angles, which can be a measure of the structural distortion, are 158.6° for RbSrNb2O6F, 149.6° for RbCaNb2O6F and 139.5° for RbNb2O5F. As the bond angle decreases, the band gap increases: 3.48eV for RbSrNb2O6F, 3.75eV for RbCaNb2O6F and 4.03 eV for RbNb2O5F. This experimental result implies that the band gap can be controlled with a range of 0.6 eV through a variation of local structure for the Nb-containing oxyfluorides.

Implicit와 explicit 방법의 결합에 의한 3차원 유한차분 빔전파 방법의 개선

김현준,오범환,박세근,이일항,이승걸,Kim, Hyun-Jun,O, Beom-Hoan,Park, Se-Geun,Lee, El-Hang,Lee, Seung-Gol 한국광학회 2004 한국광학회지 Vol.15 No.6

3차원 유한 차분 빔전파 방법의 계산시간 및 수렴성 문제를 해결하기 위해서 implicit와 explicit 방법을 결합하는 복합 방법(hybrid method)을 제안하였다. 방향성 결합기의 결합길이를 결정하는 문제를 대상으로 제안된 방법과 implicit 방정식의 해를 직접 구하는 방법의 계산 시간을 비교하였다. 그 결과 직접 풀이법에 비해 제안된 방식의 계산 속도가 최소 10배 이상 빠름을 확인하였다. We propose a hybrid method combining the implicit with the explicit methods in order to reduce the calculation time and improve the convergence problem of the 3-dimensional finite-difference beam propagation method. The numerical simulation of a directional coupler is carried out by the proposed method. It is found from the simulation results that the calculation speed of our method is 10 times faster than that of direct solving techniques.

전장축소형 무화염 소염기 형상설계 연구

김현준,이준호,채제욱,이성배,김인우,Kim, Hyun-Jun,Lee, Joon-Ho,Chae, Je-Wook,Lee, Sung-Bae,Kim, In-Woo 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.6

This paper includes that there are results of designing the flash hider and analyzing fluid dynamics of a front area of the barrel to shorten the length of small arms. Generally, the muzzle flash can be generated out of the barrel by the reaction between the oxygen in the air and unburned gunpowder contained in the propellant gas if a barrel is not long enough to burn gunpowder fully inside of the barrel. Though, the hugh muzzle flash, which is a characteristic of small arms with short barrel length, caused a soldier to aim at the target at night by making the soldier blind for a while and endangers his life by revealing firing position to enemies. Besides, the heat of muzzle flash can weaken the performance of thermal sights, which are attached to small arms for night battlefield. In this paper, flash hiders with several different shapes were designed for a newly developed 5.56mm caliber rifle with short barrel length. The performance of each flash hider to reduce the muzzle flash was compared theoretically and experimentally. Through the authorized test procedure, a highly efficient design of flash hider for reducing the muzzle flash was identified. The result of the paper can be helpful when designing flash hiders for small arms with short barrel length.

분산도 분석에 의한 총열 잔여수명 예측에 관한 연구

김현준,Kim, Hyun-Jun 한국군사과학기술학회 2009 한국군사과학기술학회지 Vol.12 No.2

This paper includes that there is the way to make the prediction of the remaining life of the barrel in small arms using analyzing dispersion. There are some ways to know the period to change the barrel such as the method of detecting the inner surface directly or inspecting the scratch using the optical sensor. However, it is a more easy way to check the dispersion for soldiers and the directors in a logistics command. Therefore, this study is conducted to focusing on the relation between firing round and dispersion. And the simple equation experimentally derives from pre-tests and analyses. Also, this equation is confirmed through the firing tests during the period of developing K11. In that sense, it can be easily applied to know the period of changing the barrel of small arms in the field army.

Seminal Tumor Necrosis Factor-alpha Level and Sperm Nuclear DNA Integrity in Healthy Donors

김현준,지병철,문정희,이정렬,서창석,김석현,Kim, Hyun-Jun,Jee, Byung-Chul,Moon, Jeong-Hee,Lee, Jung-Ryeol,Suh, Chang-Suk,Kim, Seok-Hyun The Korean Society for Reproductive Medicine 2009 Clinical and Experimental Reproductive Medicine Vol.36 No.1

Objectives: Seminal concentration of tumor necrosis factor-alpha (TNF-${\alpha}$) relevant to sperm nuclear DNA integrity has not been studied. The present study aimed to evaluate seminal concentration of TNF-${\alpha}$ in correlation with sperm parameters and nuclear DNA integrity in asymptomatic healthy donors. Methods: Semen samples were obtained by masturbation from forty-five healthy donors. Results: Sperm quality was assessed by computer-assisted semen analysis and nuclear DNA integrity measured by the TUNEL assay in raw semen. TNF-${\alpha}$ concentrations were measured by ELISA in frozen-thawed seminal plasmas. Sperm DNA fragmentation rates were ranged between 1.9% and 53.0% (mean${\pm}$SD, 12.4${\pm}$9.6%). Univariate analysis revealed that DNA fragmentation rate was not associated with sperm concentration or motility but had a correlation with linearity negatively (r=-0.325, p=0.03) and age positively (r=0.484, p=0.001). The mean seminal concentration of TNF-${\alpha}$ was 4.9 pg/mL with a range from 1.1 to 22.6 pg/mL. The TNF-${\alpha}$ concentration had no correlation with clinically relevant parameters of sperm quality or nuclear DNA fragmentation rate. Conclusion: Our results indicate that sperm nuclear DNA fragmentation may be not associated with seminal TNF-${\alpha}$ level or sperm quality in asymptomatic healthy donors. 목 적: 정액 내 tumor necrosis factor-alpha (TNF-${\alpha}$) 농도와 정자 DNA 손상 및 정액 검사 소견과의 관련성을 평가하고자 하였다. 연구방법: 정액 표본은 45명의 건강한 남성에서 자위에 의하여 획득하였다. 정자의 상태는 컴퓨터 정액 분석기를 이용하여 판정하였으며, 두부의 DNA 손상은 TUNEL 분석방법에 의해 측정하였다. TNF-${\alpha}$ 농도는 동결-융해된 정장액에서 ELISA법으로 측정하였다. 결 과: 정자 DNA 손상율은 1.9%에서 53% (mean ${\pm}$ SD, 12.4${\pm}$9.6%)로 매우 광범위하게 나타났다. 단변량분석에 의하면 DNA 손상 정도와 정자의 농도, 운동성과는 관련이 없었으나, 직진운동성 (linearity)과는 음의 상관 관계를 나타내었으며 (r=-0.325, p=0.03) 연구 대상 남성의 연령과는 양의 상관 관계를 나타내었다 (r=0.484, p=0.001). 정액내에 존재하는 TNF-${\alpha}$ (>1 pg/mL)는 연구 대상 남성의 73.3% (33/45)에서 검출되었으며 평균 농도는 4.9 pg/mL, 범위는 1.1에서 22.6 pg/mL이었다. 정액 검사 상의 정자 상태와 정자 DNA 손상과는 유의한 관련성이 나타나지 않았다. 결 론: 본 연구에서는 정자 DNA의 손상이 남성의 연령과 관련성이 있음을 확인하였으나, TNF-${\alpha}$와의 관련성은 확인할 수 없었다.

무인항공기를 이용한 콘크리트 균열 탐지 기술

김현준,심성한,조수진,Kim, Hyun Jun,Sim, Sung Han,Cho, Soo Jin 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회지 Vol.19 No.1

Crosslinked IIR 의 블렌드비에 따른 EPDM 의 내기체투과특성 향상

김현준,정일현,홍인권,박재우 ( Hyun Jun Kim,Il Hyun Jung,In Kwon Hong,Jae Woo Park ) 한국고무학회 1998 엘라스토머 및 콤포지트 Vol.33 No.3

N/A It is well known that EPDM(ethylene propylene clime monomer) rubber has inherently excellent resistance to the weathering, ozone, heat, cold rind moisture, whereas crosslinked IIR(isobutylene isoprene divinyl benzene terpolymer) shows proper resistance to the water and gas permeation. Various characteristics of EPDM bend with crosslinked IIR such as curing characteristics, mechanical properties, dispersion of minor component and gas impermeability were explored. The optimum curing tine(t_(90)) examined with peroxide was decreased by adding small amount of crosslinked IIR to the EPDM rubber. Mechanical properties of blends such as tensile strength, hardness and elongation at break were enhanced by increasing EPDM content.. These results might be explained with the affinity of carbon black to the EPDM rubber. On the other hand, the physical properties were not changed significantly after aging, and the increase of crosslinked IIR fraction caused the decrease of compression set to small rate. EPDM rubber shows different behavior with crosslinked IIR in oxygen permeability. By adding 30wt.% crosslinked IIR to the EPDM rubber, the resistance to the oxygen permeation was improved up to three times than that of pure EPDM rubber. Conclusively, EPDM blend containing 30wt.% crosslinked IIR might be commercially applied to the o-ring and electric parts because of its proper resistance to the weathering, ozone and oxygen permeability.

시호억간탕(柴胡抑肝湯) 등 약물(藥物)의 처치(處置)가 구속(拘束) 스트레스로 유발(誘發)된 생쥐의 혈(血) 중(中) Corticosterone 변화(變化)에 미치는 영향(影響)

김현준,이태희,Kim Hyun-Jun,Lee Tae-Hee 대한한의학방제학회 2002 大韓韓醫學方劑學會誌 Vol.10 No.2

To investigate the effect of Qi promoting-agents, clearing heat of deficiency type-agent, clearing heat of excessive type-agent, warming interior part of body-agent and Shihoieokgan-Tang against the immobilization stress, Cypri Rhizama, Auranti pericarpium, Aucklandiae Radix and Bupleuri Radix, Soyo-San, Hwangyeonhaedok-Tang, Geongangbuja-Tang and Shihoieokgan-Tang was administered intragastically 1hr prior to immobilizaiton stress and the change of corticosterone level has been measured by the flurometric method. The results obtained are as follows: 1. Qi promoting-agents(Cypri Rhizama, Auranti pericarpium, Aucklandiae Radix and Bupleuri Radix) showed mildly reducing effect or did not shown the reducing effect against the elevated coritocostereone level induced by the immobilization stress in the mice. 2. Hwangyeonhaedok-Tang, Gungangbuza-Tang, and Soyo-San did not show the reducing effect against the elevated corticostereone level induced by the immobilization stress in the mice. 3. Shihoieokgan-San was effective against the elevated corticosterone level induced by the immobililzation stress at 1g/kg, 3g/kg respectively. Consequently these data proved that Qi pomoting-agents as single herb(Cypri Rhizama, Auranti pericarpium, Aucklandiae Radix and Bupleuri Radix), clearing heat of deficiency type-agent(Soyo-San), warming interior part of the body(Gungangbuza-Tang), clearing heat of excessive type-agent(Hwangyeonhaedok-Tang) have no effect to decrease the elevated corticosterone level in mice exposed to the immobilization stress. Therefore our study revealed that Shihoieokgan-San which has the effects of herbs and formulae mentioned above decreased the elevated corticosterone level in mice exposed to the immobilization stress significantly.

The Clinical Significance of Serum Vascular Endothelial Growth Factor Levels Measured at Ovulation Triggering Day In Intrauterine Insemination Cycles

김현준,지병철,서창석,김석현,최영민,김정구,문신용,Kim, Hyun-Jun,Jee, Byung-Chul,Suh, Chang-Suk,Kim, Seok-Hyun,Choi, Young-Min,Kim, Jung-Gu,Moon, Shin-Yong The Korean Society for Reproductive Medicine 2007 Clinical and Experimental Reproductive Medicine Vol.34 No.1

Objective: The objective of this study was to investigate whether serum levels of vascular endothelial growth factor (VEGF) measured at ovulation triggering day reflect ovarian response in intrauterine insemination (IUI) cycles. Methods: Forty-nine fertile women who undergoing superovulation and IUI were included. Superovulation was performed using clomiphene citrate (100 mg/d on day 3$\sim$7) in combination with human menopausal gonadotropin (150 IU every other day starting on day 5). Serum samples were obtained on the day of hCG administration and the levels of VEGF-A and estradiol were measured. The numbers of mature follicle $\geq$17 mm in diameter were also counted. Results: Serum VEGF-A levels did not correlate with the numbers of mature follicle count nor serum estradiol levels. Serum estradiol level was positively associated with mature follicle count. Serum VEGF-A levels tended to be lower in women with mature follicle count less than three or women with more than five. Conclusion: Our results indicate that serum VEGF-A levels do not have an association with superovulation outcome in IUI cycles. However, a tendency of lower VEGF-A level in poor and high responder suggests that those with extreme response to superovulation may be related with abnormal angiogenesis. Further studies should be warranted in larger populations. 목 적: 자궁강 내 인공수정을 위한 과배란유도 시 혈청 vascular endothelial growth factor (VEGF) 농도가 과배란유도의 결과를 반영할 수 있는지를 확인해 보고자 하였다. 연구방법: 과배란유도 후 자궁강 내 인공수정을 시행 받은 49 명의 불임여성을 대상으로 hCG 투여 일에 혈청을 얻어 VEGF-A 및 estradiol 농도를 측정하였다. 과배란유도는 clomiphene citrate (100 mg/d on day 3$\sim$7) 와 human menopausal gonadotropin (150 IU every other day starting on day 5) 병합요법을 이용하였다. hCG 투여 일에 17mm 이상의 성숙난포 수와 자궁내막 두께를 동시에 측정하였다. 결 과: 혈청 VEGF-A 농도는 성숙난포 수, estradiol 농도 및 자궁내막 두께와는 무관하였던 반면 성숙난포 수와 estradiol 농도는 양의 비례관계를 보였다. 혈청 VEGF-A 농도는 성숙난포 수가 2 개 이하인 저 반응 군과 6 개 이상인 고 반응 군에서 통계적으로 유의하지는 않지만 낮은 수치를 보였다. 결 론: 혈청 VEGF-A 농도는 자궁강 내 인공수정 시술 시 과배란유도의 결과와 무관한 것으로 사료되지만 저 반응 군과 고 반응 군에서 낮은 농도를 보이는 것으로 보아 이들을 대상으로 한 추가 연구가 필요할 것으로 판단된다.