• 조명전기설비학회논문지
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• 제14권2호
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• pp.89-96
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• 2000

본 논문은 최근의 반도체 스위칭 소자(Power-MCSEFET)를 사용하여 상용화의 관점에서 회로구성이 간단하고 취급이 용이한 Frward형 펼스 전원장치에 관하여 기술하고 있다. Forward형 고주파 펄스 전원장치에 인가되는 펄스전압의 최대값은 브리지 청류회로띄 위상각 제어에 의해서 이루어지고 있으며, 펄스전압은 Power-MOSFET의 듀티비에 의해 펼스주기가 정해진다. 또한, 본 논운에셔는 Forward형 펄스 전원장치의 회로동작과 전원장치의 특성 및 전원장치의 방전특성을 스위칭 주파수와 위상각의 변화에 따라서 검토하였다. 첨가해, 펄스 전원장치를 제작하여 램프형 오전발생기를 부하로 하였을 때 이론해석과 특성해석의 정당성을 입증하였다. 본 장치는 향후 다양한 분야로의 펄스 전원 시스템에 응용.가능성을 보여주고 있다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.95-100
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• 1995

This study investigated the effects of mechanical factors involved in several corneal refractive surgeries on the surgical outcomes. Then we proposed possible new techniques from the mechanical point of a view utilizing finite element method. The models studied are: circumferential keratetomy, combination of excimer laser photorefractive keratectomy and circumferential keratotomy for myopia treatment, arcuate keratotomy for astigmatism treatment. The cornea was assumed to be nonlinear elastic and almost incompressible material as the most soft tissue in the human body. In the circumferential keratotomy the effect of the incision location was investigated. The angle and location of the incision were varied to predict the surgical outcomes in the arcuate keratotomy. The finite element analysis results showed that the location of incision was a critical factor affecting the surgical outcomes in the circumferential keratotomy. In the combination of the excimer laser photorefractive keratectomy and circumferential keratotomy, it was predicted that the circumferential can increase or decrease the refractive power depending on the incision location or it can be used to adjust the overcorrection of undercorrection. In the arcuate keratotomy for astigmatism, the most diopter changes were predicted when the location and the angle of the incision were 3.0mm from the apex and $90^{\circ}$, respectively. In the arcuate keratotomy, the effects of an incision were studied within the incision area as well as outside the incision area. Also, the arcuate keratotomy with two incisions located on the opposite area of the cornea was also studied. As a conclusion, the finite element method is a useful technique in the area of corneal refractive surgeries to develop new techinques.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.411-412
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• 2008

We have studied a property change of organic light-emitting diodes (OLED) due to an indium tin oxide (ITO) surface reformation. The characteristics of OLED were improved by oxygen plasma processing of an ITO in this work. ITO is widely used as a transparent electrode in light-emitting devices, and the OLED device performance is sensitive to the surface properties of the ITO. The OLED devices with the structure of ITO/TPD(50nm)/$Alq_3$(70nm)/LiF(0.5nm)/Al(100nm) were fabricated, and the surface properties of ITO were investigated by using various characterization techniques. The oxygen plasma process of an ITO was processed by using RF power of 125W and oxygen partial pressure of $2\times10^{-2}$ Torr. The oxygen plasma processing of an ITO processed for 0/1/2/3/4min. Current-voltage-luminance characteristics of the devices show that turn-on voltage is 4V for 2min device and the luminance reaches about 27,000cd/$m^2$ for 4min device. The current efficiency shows that 3min device becomes saturated to be about 8cd/ A. They show that emission was from the $Alq_3$ layer, because the peak wavelength is about 525nm. View angle-dependent emission spectra show that the emission intensity decreases as the angle increases.

• 한국재료학회지
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• 제25권1호
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• pp.1-8
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• 2015

This study suggested comprehensive structural characterization methods for the commercial blue light emitting diodes(LEDs). By using the Z-contrast intensity profile of Cs-corrected high-angle annular dark field scanning transmission electron microscope(HAADF-STEM) images from a commercial lateral GaN-based blue light emitting diode, we obtained important structural information on the epilayer structure of the LED, which would have been difficult to obtain by conventional analysis. This method was simple but very powerful to obtain structural and chemical information on epi-structures in a nanometer-scale resolution. One of the examples was that we could determine whether the barrier in the multi-quantum well(MQW) was GaN or InGaN. Plan-view TEM observations were performed from the commercial blue LED to characterize the threading dislocations(TDs) and the related V-pit defects. Each TD observed in the region with the total LED epilayer structure including the MQW showed V-pit defects for almost of TDs independent of the TD types: edge-, screw-, mixed TDs. The total TD density from the region with the total LED epilayer structure including the MQW was about $3.6{\times}10^8cm^{-2}$ with a relative ratio of Edge- : Screw- :Mixed-TD portion as 80%: 7%: 13%. However, in the mesa-etched region without the MQW total TD density was about $2.5{\times}10^8cm^{-2}$ with a relative ratio of Edge- : Screw- :Mixed-TD portion of 86%: 5%: 9 %. The higher TD density in the total LED epilayer structure implied new generation of TDs mostly from the MQW region.

• Journal of Animal Science and Technology
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• 제52권6호
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• pp.467-473
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• 2010

A total of 4,323,781 records for informal 16 primary linear descriptive traits of dairy cows in Holstein breed from 1988 to 2007 in USA were analyzed to estimate adjustment factors for lactation number and stage. While all factors in the model were highly significant (P < 0.01), major influences on linear type traits were due to lactation number and stage. The frequencies of lactation number 1 through 6 were 58.6, 22.0, 11.8, 4.8, 2.1, and 0.8%, respectively. Further, the frequencies of lactation stage were 0.7, 76.9, 15.3, 4.9, and 2.1%, respectively, for springing, early, medium, late, and dry. To adjust 16 linear traits (stature, dairy form, strength, body depth, rump width, rump angle, legs rear view, leg set, foot angle, fore udder, rear udder height, rear udder width, udder support, udder depth, and front teat placement), additive and multiplicative adjustment factors of lactation number (lactations 2 to 4) and stage (springing, medium, late and dry) were estimated with the solutions in the generalized linear model, assigning lactation 1 and stage early as base class. Additive adjustment factors of lactation number ranged from -1.23 to 2.908, while multiplicative factors ranged from 0.853 to 2.207. Further, additive and multiplicative adjustment factors for lactation stage ranged from -0.668 to 0.785, and from 0.891 to 1.154. Application of adjustment factors to 20 randomly sampled sub-data sets produced the results that additive adjustment factors for both lactation number and stage reduced more mean square of lactation number and stage over 16 linear traits than any combination of adjustments, and leaded additive adjustment factors for both lactation number and stage as a choice of methods for adjustment of informal 16 primary linear type traits collected by classifiers of AI studs.

• 한국군사과학기술학회지
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• 제15권6호
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• pp.721-728
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• 2012

The tracked SUGVs(Small Unmanned Ground Vehicles) are frequently operated in the narrow slope such as stairs and trails. But due to the nature of the tracked vehicle which is steered using friction between the track and the ground and the limited field of view of driving cameras mounted on the lower position, it is not easy for SUGVs to trace narrow slopes. To properly trace inclined narrows, it is very important for SUGVs to keep it's heading direction to the slope. As a matter of factor, no roll value control of a SUGV can makes it's heading being located in the direction of the slope in general terrains. But, the problem is that we cannot directly control roll motion for SUGV. Instead we can control yaw motion. In this paper, a new slope driving method that enables the vehicle trace the narrow slopes with IMU sensor usually mounted in the SUGV is suggested which including an estimation technique of the desired yaw angle corresponding to zero roll angle. In addition, a fuzzy steering controller robust to changes in driving speed and the stair geometry is designed to simulate narrow slope driving with the suggested method. It is shown that the suggested method is quite effective through the simulation.

• Archives of Plastic Surgery
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• 제45권1호
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• pp.23-28
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• 2018

Background Condylar process fractures account for one-third of all mandibular fractures, and the distal fragment is prone to dislocate to the medial side due to the pulling of the lateral pterygoid muscle. Retromandibular approaches are commonly used, but the intraoperative view becomes limited in medially dislocated fractures. This study summarized a series of cases of retromandibular reduction for medially dislocated condylar process fractures and described our supplementary procedure to realign the dislocated condylar process. Methods Nine patients with medially dislocated condylar process fractures underwent surgical correction from January 2012 to December 2016. In 6 of them, it was possible to realign the fractures with a conventional retromandibular approach, but for 3 cases of severe dislocation to the middle cranial fossa, a supplementary transoral procedure was carried out. The angle difference between the ramus and condyle, ramus height, and maximal mouth opening (MMO) were evaluated. Results All 9 cases were restored to the proper anatomical alignment without any major complications, and postoperative images revealed successful union. The angle difference was $8.94^{\circ}{\pm}4.11^{\circ}$ preoperatively, and $0.99{\pm}0.49^{\circ}$ at the 6-month follow-up. The pretreatment ramus height difference was $6.12{\pm}6.09mm$, and the postoperative difference was $0.18{\pm}0.10mm$. These changes after surgery were statistically significant. The MMO before surgery was $11.44{\pm}3.0mm$, and the postoperative MMO was $37.2{\pm}2.9mm$, reflecting a significant increase after reduction. Conclusions Retromandibular reduction is a useful method in medially dislocated condylar process fractures, and additional transoral assistance should be considered to realign condylar processes that severely dislocate to the middle cranial fossa.

• 항공우주기술
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• 제7권1호
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• pp.24-29
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• 2008

최근의 유가인상과 관련하여 상업용 및 군용 항공기 운용시의 연료 효율을 높이고자 하는 노력이 가속화되고 있다. 관련 연구에 의하면 수송기와 비즈니스 젯 항공기에 있어서 윙렛은 공력/구조적 효율성을 향상시키고, 적은 중량 증가로 저속 수송기의 상승 성능을 향상시킨다고 보고된 바 있다. 윙렛은 일반적으로 날개 끝에 장착되는 작은 공력면이며, 날개에 수직에 가깝게 장착되어 날개 끝단 와류의 순환 유동장내에서 작용한다. 윙렛의 설계는 위치, 높이, 테이퍼비, 후퇴각, 익형, toe-out 및 켄트각 등 많은 요소를 고려해야 하는 매우 복잡한 과정이다. 최근에는 미국 보잉사의 B737-800과 B787 등의 최신 기종에서 Blended 윙렛을 성공적으로 적용하여 날개끝의 길이를 늘리는 것(Wing Tip Extension) 보다 적은 추가 중량으로 같은 순항 성능을 도출하는데 성공하였다. 윙렛의 점성저항으로 인하여 최소항력은 증가하지만 높은 양력계수에서는 유도항력의 감소로 전체 항력이 감소하게 됨을 알 수 있다. 따라서, 윙렛은 강한 날개끝 와류를 발생시키는 높은 양력계수에서 순항하는 항공기에 더욱 적합하다.

• Animal Bioscience
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• 제37권4호
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• pp.555-566
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• 2024

Objective: This study aimed to assess the genetic parameters and accuracy of genomic predictions for twenty-four linear body conformation traits and overall conformation scores in Korean Holstein dairy cows. Methods: A dataset of 2,206 Korean Holsteins was collected, and genotyping was performed using the Illumina Bovine 50K single nucleotide polymorphism (SNP) chip. The traits investigated included body traits (stature, height at front end, chest width, body depth, angularity, body condition score, and locomotion), rump traits (rump angle, rump width, and loin strength), feet and leg traits (rear leg set, rear leg rear view, foot angle, heel depth, and bone quality), udder traits (udder depth, udder texture, udder support, fore udder attachment, front teat placement, front teat length, rear udder height, rear udder width, and rear teat placement), and overall conformation score. Accuracy of genomic predictions was assessed using the single-trait animal model genomic best linear unbiased prediction method implemented in the ASReml-SA v4.2 software. Results: Heritability estimates ranged from 0.10 to 0.50 for body traits, 0.21 to 0.35 for rump traits, 0.13 to 0.29 for feet and leg traits, and 0.05 to 0.46 for udder traits. Rump traits exhibited the highest average heritability (0.29), while feet and leg traits had the lowest estimates (0.21). Accuracy of genomic predictions varied among the twenty-four linear body conformation traits, ranging from 0.26 to 0.49. The heritability and prediction accuracy of genomic estimated breeding value (GEBV) for the overall conformation score were 0.45 and 0.46, respectively. The GEBVs for body conformation traits in Korean Holstein cows had low accuracy, falling below the 50% threshold. Conclusion: The limited response to selection for body conformation traits in Korean Holsteins may be attributed to both the low heritability of these traits and the lower accuracy estimates for GEBVs. Further research is needed to enhance the accuracy of GEBVs and improve the selection response for these traits.

• 대한방사선기술학회지:방사선기술과학
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• 제32권1호
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• pp.101-106
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• 2009

본 연구는 FLASH 펄스파형을 이용하여 숙임각(flip angle ; FA)변화에 따른 T1 강조영상의 신호강도(signal intensity ; SI)와 대조도 대 잡음비(contrast to noise ratio ; CNR)를 비교함으로써 복부검사에서의 최적의 T1효과를 나타내기 위한 FA를 알아보고자 하였다. 2008년 9월부터 12월까지 본원을 내원하여 복부 MRI 검사를 시행한 환자 20명(남 : 12명, 여 : 8명, 연령 범위 : $28{\sim}63$세, 평균 : 51세)을 대상으로 하였다. 영상 장비는 3Tesla MR scanner(Magnetom Tim Trio, SIEMENS, Germany)였으며, 8 channel body array coil을 사용하였다. 사용된 영상변수는 FLASH 펄스파형과 TR : 120 ms, TE : minimum, FOV : $360{\times}300\;mm$, Matrix : $256{\times}224$, Slice : 6 mm, scan time : 15초로 Breath-hold 기법을 이용하였다. 복부 영상은 물 신호를 동시에 측정하기 위해 관심영역(FOV) 안에 물을 채운 50 ml syringe를 놓고 $10^{\circ}$부터 $90^{\circ}$까지 $10^{\circ}$ 간격으로 FA에 변화를 주면서 얻었다. 획득한 영상은 간(liver), syringe내부의 물(water), 비장(spleen), background의 신호강도(SI)와 대조도 대 잡음비(CNR)를 각각 측정하였으며 신호강도는 관심영역을 설정한 다음 각 부위에서 3번씩 측정하고 그 평균값을 구하였다. 영상 전체의 평가에서는 변이계수(coefficient of variation)를 적용하여 전체영상의 신호강도 균일도를 알아보았고 통계 분석은 SPSS for window version 17.0을 이용하였다. 간(liver)의 신호강도는 $475.54{\pm}81.76$으로 FA $40^{\circ}$에서 가장 높게 나타났으며 syringe내부의 물의 신호는 $475.97{\pm}68.98$로 FA $20^{\circ}$에서 가장 높았으며 FA가 높아짐에 따라 다른 조직의 신호보다 많은 감소를 보였다. 비장의 신호는 $443.02{\pm}55.77$로 FA $30^{\circ}$에서 가장 높은 신호강도를 보였으며 FA가 높아짐에 따라 신호가 감소하였다. 조직의 신호강도에서 Liver vs Water와 Liver vs Spleen은 FA $30^{\circ}$를 제외한 전 구간에서 통계적으로 유의한 차이를 보였고 Water vs Spleen은 FA $60^{\circ}$, FA $70^{\circ}$, FA $80^{\circ}$에서만 유의한 차이를 보였다(p < 0.01). 전체영상의 신호강도는 $175.42{\pm}57.93$으로 FA $10^{\circ}$에서 가장 낮게 나타났으며 FA가 높아짐에 따라 증가하다가 떨어지는 양상을 보였다. 또한 변이계수(coefficient of variation)는 FA $10^{\circ}$와 FA $20^{\circ}$에서 33.02와 31.43으로 가장 높게 나타났다. FA $10^{\circ}$와 FA $20^{\circ}$는 전체영상의 신호강도 균일도가 다소 떨어지는 영상으로 왜곡이 심하게 나타났다. CNR은 liver-water에서 FA $30^{\circ}$에서 12.73으로 가장 낮게 나타났고 FA $10^{\circ}$에서 -46.97, FA $80^{\circ}$에서 29.36으로 가장 높게 나타났다. liver-spleen의 CNR에서는 FA $10^{\circ}$에서 -3.18로 가장 낮게 나타났으며 FA $80^{\circ}$에서 9.65로 가장 높게 나타났다. 결론적으로 FLASH 펄스 파형을 사용한 복부 영상에서 최적의 T1효과를 나타내기 위해서는 FA $80^{\circ}$를 사용하는 것이 유용할 것으로 생각된다.