• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.410.2-410.2
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• 2016

Tandem structure is promising in organic solar cells because of its double open-circuit voltage (VOC) and efficient photon energy conversion. In a typical tandem device, the two single sub-cells are stacked and connected by an interconnecting layer. The fabrication of two sub-cells are usually carried out in a glovebox filled with nitrogen or argon gas, which makes it expensive and laborious. We report a glovebox-free fabricated inverted tandem organic solar cells wherein the tandem structure comprises sandwiched interconnecting layer based on p-doped hole-transporting, metal, and electron-transporting materials. Complete fabrication process of the tandem device was performed outside the glove box. The tandem solar cells based on poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61-butyric acid methyl ester (PCBM) can realize a high VOC, which sums up of the two sub-cells. The tandem device structure was ITO/ZnO/P3HT:PCBM/PEDOT:PSS/MoO3/Au/Al/ZnO-d/P3HT:PCBM/PEDOT:PSS/Ag. The separate sub-cells were morphologically and thermally stable up to 160 oC. The high stability of the active layer benefits in the fabrication processes of tandem device. The performance of tandem organic solar cells comes from the sub-cells with an 50 nm thick active layer of P3HT:PCBM, achieving an average power conversion efficiency (PCE) of 2.9% (n=12) with short-circuit current density (JSC) = 4.26 mA/cm2, VOC = 1.10 V, and fill factor (FF) = 0.62. Based on these findings, we propose a new method to improve the performance and stability of tandem organic solar cells.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.650-655
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• 2016

본 논문에서는 요소수를 적용하는 SCR 인젝터의 내부유동에 대한 전산 유동해석을 수행하였다. 유동해석에 적용된 인젝터는 경사진 노즐과 스월디스크를 갖는 스월타입의 단홀 인젝터이다. 인젝터 니들의 최대 리프트 및 열림 속도를 인젝터의 설계 변수로 선정하였다. 비정상 상태로 작동하는 노즐 내부의 유동 특성을 해석하기 위하여, 움직이는 물체에 적용이 가능한 Moving Grid 기법을 적용하여 정밀한 인젝터 니들의 움직임을 모사하였다. 유동해석 결과, 인젝터 니들의 속도가 증가할수록 출구를 통한 요소수 유량은 감소하는 것으로 나타났다. 이는 인젝터 니들의 속도가 빨라질수록, 인젝터 니들 하부의 빈 공간을 채우려는 유량이 증가하고, 이러한 요소수 유량의 증가가 노즐 출구로 방출되는 유량의 감소를 유발하게 된다. 요소수 유동이 인젝터 노즐에서 출구 쪽으로 진행할수록, 스월 유동은 감소하였다. 이는 유동과 노즐 벽면과의 마찰에 기인한 것으로 사료된다. 또한, 최대 리프트 유지기간에서, 니들 리프트가 높을수록 스월 계수와 평균 스월 계수가 증가하는 경향을 보였다. 본 연구의 결과는 관련된 Urea-SCR 인젝터의 기본 설계 자료로 활용될 수 있을 것이다.

• Carbon letters
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• 제19권
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• pp.72-78
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• 2016

Spinnable pitches and carbon fibers were successfully prepared from petroleum or coal pyrolysis residues. After pyrolysis fuel oil (PFO), slurry oil, and coal tar were simply filtered to eliminate the solid impurities, the characteristics of the raw materials were evaluated by elemental analysis, ¹³C nuclear magnetic resonance spectrometer, matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS), and so on. Spinnable pitches were prepared for melt-spinning carbon fiber through a simple distillation under strong nitrogen flow, and further vacuum distillation to obtain a high softening point. Carbon fibers were produced from the above pitches by single-hole melt spinning and additional heat treatment, for oxidization and carbonization. Even though spinnable pitches and carbon fibers were processed under the same conditions, the melt-spinning and properties of the carbon fiber were different depending on the raw materials. A fine carbon fiber could not be prepared from slurry oil, and the different diameter carbon fibers were produced from the PFO and coal tar pitch. These results seem to be closely correlated with the initial characteristics of the raw materials, under this simple processing condition.

• Journal of Periodontal and Implant Science
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• 제24권2호
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• pp.390-396
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• 1994

This study investigates the effect of wind instrument playing on the periodontal condition by comparing and analyzing wind instrument players and non-wind instrument players by various clinical paramenters, including periodontal index, bleeding index, simplified oral hygiene index, and non-functional tooth index. The subjects consist of 65 wind instrument players and 31 non-players. The players were divided into 4 groups ; Those who use cup-shaped mouthpieces as Group A, single reed mouthpieces as Group B, double reed mouthieces as Group C, and hole mouthpieces as Group D. Non-players are designated as Group E. The results are as follows ; 1. Periodontal Index Group A recorded $1.2{\pm}0.7$, Group B $1.1{\pm}0.7$, Group C $1.3{\pm}0.5$, Group D $2.1{\pm}0.5$, and Group E $0.9{\pm}0.6$, with no statistically significant differences among the groups. 2. Bleeding Index Group A shwed 0.23, Group B 0.25, Group C 3.0, Group D 0.38, and Group E 0.23, with no statistically significant differences among the groups. 3. Non-functional Tooth Index Group A recorded 2.0, Group B 1.0, Group C 3.0, Group D 0, Group E 0.7, with no statistically significant differences among the groups. 4. Simplified Oral Hygiene Index Buccal sides of maxillary 1st molars, lingual sides of mandibular 1st molars, labial sides of maxillary anterior teeth, and lingual sides of mandibular anterior teeth were investigated, and there was no statistically significant differences among the groups.

• 화약ㆍ발파
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• 제34권1호
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• pp.11-18
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• 2016

도심지나 보안건물과 근접한 곳에서 폭약을 사용하는 발파작업이 수행되는 경우 지반진동 및 소음의 영향을 최소화 시킬 필요가 있다. 이러한 지반진동과 소음은 암반의 천공내에 장전된 폭약이 기폭되며 주변 암반을 파괴하고 남은 일부 충격에너지에 의하여 발생된다. 최근 천공 내 U형 철재장약홀더를 삽입하여 충격파의 전파방향을 제어하여 자유면방향으로 파쇄효과를 유지하며 암반 내로 전파하는 충격진동을 감쇄시키는 발파 공법이 제안되었다. 본 연구에서는 U형 철재장약홀더를 적용한 암반발파에서 충격파의 전파특성을 파악하기 위하여, AUTODYN 소프트웨어를 이용하여 장약홀더 내 장전된 폭약의 폭굉을 모사하고 주변암반에 전달된 충격파를 측정하였다. 또한 장약홀더 발파의 암파쇄 효과를 파악하기 위하여 동적파괴과정해석코드인 DFPA(Dynamic Fracture Process Analysis)를 적용하여 장약홀더를 이용한 장약조건을 고려한 2자유면 발파를 모사하였다. 일반발파의 장약조건을 고려한 충격파 발생 및 파괴과정해석을 추가적으로 수행하여 장약홀더의 암파쇄효과를 비교하였다.

• Applied Microscopy
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• 제30권2호
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• pp.185-191
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• 2000

초고온 archaeon인 Thermococcus profundus에서 매우 거대한 단백질 복합체를 분리 및 구조를 규명하였다. 거대 복합체는 93kDa단백질(P93 complex)로 구성된 homomultimer이며, 강한 내열성을 보여주고 있다. 순수 분리한 P93 complex를 SDS(최종 농도 1%)와 $85^{\circ}C$에서 12시간 항온시킨 후, SDS-PAGE와 전자현미경에서 구조적 변화를 관찰할 수 없었다. 음착색된 P93 complex의 전자현미경 사진에서 하나의 형태만을 보여주고 있으며, 구조의 규명을 위해 image processing을 하였다. 이의 구조는 3대칭 중심에 core(혹은 hole)이 뚜렷이 존재하며 이를 중심으로 단백질이 모여 있는 형태를 보여 주고 있다. 또한 P93 complex는 가장자리에서 뚜렷한 형태를 보여주지 않은 부분, 즉 flexible부분을 포함하고 있다. Gel filtration과 2차원 구조를 기초로 P93 complex는 24 homomultimer로 되어 있음을 추정하였다.

• Toxicological Research
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• 제28권2호
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• pp.103-106
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• 2012

The effect of continuous humidifier use on the bioaerosol concentration in an indoor environment was investigated. An ultrasonic humidifier was operated for 10 hr per day for 15 days in an apartment room. During this time period, viable bioaerosol samples were taken using a single-stage Andersen sampler containing culture media plates for bacteria and fungi. The culture plates were then incubated at room temperature for 2~7 days depending on the media. The counts for the air sample plates were corrected for multiple impactions using the positive hole conversion method and are reported as the colony forming units per cubic meter of air (CFU/$m^3$). While the bacterial concentration measured using the tryptic soy agar (TSA) did not show any significant change during the first 3 days, the concentration increased from the $6^{th}$ day (6979 CFU/$m^3$) and reached a maximum on the $9^{th}$ day (46431 CFU/$m^3$). The concentration then decreased to 2470 CFU/$m^3$ on the $12^{th}$ day, at which point the fungal concentration increased rapidly to 14424~16038 CFU/$m^3$. Also, while the fungal concentration showed a significant change until the $9^{th}$ day of humidifier use, fungal growth was observed on the wallpaper and increased rapidly from the $12^{th}$ day. However, the bacterial concentration increased rapidly after the fungi were removed by remediation. The major fungal species identified in the samples were Penicillium representing 34%, Aspergillus representing 31%, Cladosporium representing 24%, and Alternaria representing 1%. The results also indicated that a relative humidity over 80% was easily achieved with continuous humidifier use. Yet, maintaining a high humidity in a room can cause a rapid outbreak of microbial growth.

• 한국광학회지
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• 제21권5호
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• pp.195-199
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• 2010

본 논문에서는 광자결정 광섬유를 이용하여 1000 nm 의 광대역폭을 갖는 광신호 분배기를 구현하였다. 제작에 사용된 광자결정 광섬유의 지름은 $130{\mu}m$ 이고 6층의 공기 구멍 구조로 이루어져 있다. 광신호 분배기는 두 가닥의 광자결정 광섬유에 열을 가함과 동시에 인장력을 가해 제작하였으며 제작된 광자결정 광섬유 기반 광신호 분배기의 지름은 $23{\mu}m$ 이었다. 광신호 분배기의 제작 시 인장시키는 길이에 따라 대역폭과 bandedge가 조절되었다. 제작된 광자결정 광섬유 기반 광신호 분배기의 대역폭이 1000 nm에서 50:50의 광신호 분해 효율을 가지는 것으로 측정되었다. 광자결정 광섬유의 공기 구멍 구조의 특성으로 인해 주변온도의 변화에 영향을 받지 않는 특성을 나타낸다. Optical coherence tomography의 분해능이 광원의 대역폭에 비례하므로 광대역폭을 갖는 광자결정 광섬유 기반 광신호 분배기는 신호 추출을 위한 간섭계 구성에 핵심적으로 활용될 수 있을 것으로 사료된다.

• Journal of Korean Neurosurgical Society
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• 제30권4호
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• pp.493-500
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• 2001

Objective : Anterior cervical locking plates are the devices for achieving anterior cervical spinal fusion. This study was conducted to evaluate the locking plate system regarding its long-term advantages and disadvantages in the view of interbody fusion rate, hardware-related failures, vertebral change close to the fusion segment and postoperative complications. Method : Eight-six patients, operated from Jan., 1996 to Jun. 1998, were followed-up for more than two years. All of the cases were fused with iliac bone graft and ORION locking plate(Sofamor Danek USA, Inc., Memphis, TN) fixation. The patients were discharged or transferred to rehabilitation department 2-7 days after operation. A comprehensive evaluation of the interbody fusion state, instrument failure, vertebral change and postoperative complications were made by direct interview and cervical flexion-extension lateral plain films. Results : There were 55 male and 31 female with a mean age of 45 years(18-75 years). The mean follow-up period was 29 months(24-43 months). Various disorders that were operated were 40 cervical discs, 6 cervical stenosis including OPLL, 2 infections, and 38 traumas. Fusion level was single in 59 cases, two levels of each disc space in 15 cases, and two levels after one corpectomy in 12 cases. There was no instrument failure. Pseudoarthrosis was observed in two cases(2%) without radiological instability. The other patients(98%) showed complete cervical fusion with stable instrument. Mild settling of interbody graft with upward migration of screws was found in 12 cases(14%). Anterior bony growth at the upper segment was found in 5 cases(6%). Postoperative foreign body sensation or dysphagia was observed in 12 cases(4%), and disappeared within one month in 7 cases and within six months in 4 cases. One patient complained for more than six months and required reoperation to remove paraesophageal granulation tissue. Conclusion : The results show that Orion cervical locking plate has some disadvantages of upward migration of screws, anterior bony growth at the upper segment, or possibility of esophageal compression even though it has advantages of high interbody fusion rate or low instrument failure. Author believe that anterior cervical locking plate in the future should be thinner, and should have short end from the screw hole, and movable screw with adequate stability.

• Journal of Korean Neurosurgical Society
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• 제61권1호
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• pp.97-104
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• 2018

Objective : Diffusion-weighted magnetic resonance imaging (DW-MRI) has proven useful in the study of the natural history of ischemic stroke. However, the potential of DW-MRI for the evaluation of chronic subdural hematoma (CSDH) has not been established. In this study, we investigated DW-MRI findings of CSDH and evaluated the impact of the image findings on postoperative outcomes of CSDH. Methods : We studied 131 CSDH patients who had undergone single burr hole drainage surgery. The images of the subdural hematomas on preoperative DW-MRI and computed tomography (CT) were divided into three groups based on their signal intensity and density : 1) homogeneous (iso or low) density on CT and homogeneous low signal intensity on DW-MRI; 2) homogeneous (iso or low) density on CT and mixed signal intensity on DW-MRI; and 3) heterogeneous density on CT and mixed signal intensity on DW-MRI. On the basis of postoperative CT, we also divided the patients into 3 groups of surgical outcomes according to residual hematoma and mass effect. Results : Analysis showed statistically significant differences in surgical (A to B : p<0.001, A to C : p<0.001, B to C : p=0.129) and functional (A to B : p=0.039, A to C : p<0.001, B to C : p=0.108) outcomes and treatment failure rates (A to B : p=0.037, A to C : p=0.03, B to C : p=1) between the study groups. In particular, group B and group C showed worse outcomes and higher treatment failure rates than group A. Conclusion : CSDH with homogeneous density on CT was characterized by signal intensity on DW-MRI. In CSDH patients, performing DW-MRI as well as CT helps to predict postoperative treatment failure or complications.