• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.2
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• pp.197-204
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• 2023

The importance of each warfighting function for Army TIGER unit attack drones is measured using the AHP technique. As a result, the importance of attack drones is high in the order of maneuver, firepower, intelligence, command/control, protection, and operation sustainment, but the importance of maneuver, firepower, and intelligence are almost similar. In addition, it is analyzed that attack drones capable of carrying out day and night missions by being equipped with an EO/IR sensor and being commanded/controlled in conjunction with the C4I system to eliminate threats with small bombs or aircraft collisions is needed. Finally, based on the results of this study, a virtual battle scenario for attack drones is proposed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.50 no.1
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• pp.13-26
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• 2024

Objectives: The aim of this study was to perform a comparative analysis of the ultrastructural and chemical composition of sialoliths, tonsilloliths, and antroliths and to describe their growth pattern. Materials and Methods: We obtained 19 specimens from 18 patients and classified the specimens into three groups: sialolith (A), tonsillolith (B), and antrolith (C). The peripheral, middle, and core regions of the specimens were examined in detail by histology, micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and transmission electron microscopy (TEM). Results: In the micro-CT, group A showed alternating radiodense and radiolucent layers, while group B had a homogeneous structure. Group C specimens revealed a compact homogeneous structure. Histopathologically, group A showed a laminated, teardrop-shaped, globular structure. Group B demonstrated degrees of immature calcification of organic and inorganic materials. In group C, the lesion was not encapsulated and showed a homogeneous lamellar bone structure. SEM revealed that group A showed distinct three layers: a peripheral multilayer zone, intermediate compact zone, and the central nidus area; groups B and C did not show these layers. The main elemental components of sialoliths were O, C, Ca, N, Cu, P, Zn, Si, Zr, F, Na, and Mg. In group B, a small amount of Fe was found in the peripheral region. Group C had a shorter component list: Ca, C, O, P, F, N, Si, Na, and Mg. TEM analysis of group A showed globular structures undergoing intra-vesicular calcification. In group B, bacteria were present in the middle layer. In the outer layer of the group C antrolith, an osteoblastic rimming was observed. Conclusion: Sialoliths had distinct three layers: a peripheral multilayer zone, an intermediate compact zone and the central nidus area, while the tonsillolith and antrolith specimens lacked distinct layers and a core.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.350-359
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• 2001

목적 - 근관형성시 근관내 상아질벽에는 항상 도말층(smear layer)이 형성되는데, 이는 상아질, 치수조직 잔사, 조상아세포 돌기, 때로는 미생물 등으로 구성되며, 주사전자현미경상으로는 비규칙적이며, 무정형의 구상(granular)구조물로 관찰된다. 본 연구에서는 도말층의 유무에 따른 혐기성 미생물, Prevotella nigrescens의 근관내 상아질 부착정도를 주사전자현미경으로 평가하고자 한다. 지금까지 사용되었던 실험방법에 비하여 보다 임상적 환경에 가까운 실험방법을 고안, 신빙성 있는 연구결과를 기대할 수 있도록 하였다. 방법 - 치주질환이나 외상 등의 원인으로 발거된 상, 하악 전치 18개를 사용하였다. 각 치아의 치관부를 백악법랑경계부위에서 절단하고, 1군(5개치아)은 10ml의 생리식 염수를, 2군(5개치아)과 3군(5개치아)은 10ml의 3.5% NaOCl을 근관관주용액으로 사용하여 근관형성을 하였다. 근관형성 완료후 1군과 2군은 10ml의 생리식염수로, 3군은 10ml의 0.5M EDTA용액으로 final flush를 시행하여, 3군의 도말층을 제거하였다. 치근수직절단과 ethylene oxide(EO) gas 소독후 1, 2, 3군의 시편(각군10개시편)을 Prevotella nigrescens가 부유된 Brain Heart Infusion with Yeast estract, Hemin and Menadione(BHIYHM) broth내에 37$^{\circ}C$에서 3시간 동안 incubation했다. 4, 5, 6군은 실험과정을 검증하기 위한 대조군으로써, 4군(1개치아)과 5군(1개치아)은 1군, 2군과 같이 각각 생리식염수와 NaOCl만을 이용한 근관형성으로 도말층을 잔존시키고, 6군(1개치아)은 3군과 같이 NaOCl과 EDTA를 적용하여 도말층을 제거한 후, 치근 수직절단과 EO gas 소독을 시행했다. 모든 시편(1, 2, 3, 4, 5, 6군)을 통상의 방법에 따라 처리한 후 주사전자현미경을 통하여 관찰, 근관내면에 부착되어 있는 Prevotella nigrescens의 개수, 모양, 상아세관 및 도말층과의 관계 등을 관찰, 비교, 분석하였다. 결과는 t-test와 one-way ANOVA를 통하여 통계처리 하였다. 결론 - 1. 근관형성 후 근관내 상아질 표면 전체는 도말층으로 덮여 있는 양상을 보였다. 2. 3.5% NaOCl과 0.5M EDTA를 적용하여 근관내 도말층을 효과적으로 제거할 수 있었으며, 상아세관 개구부가 확연히 노출되어 있는 소견을 관찰할 수 있었다. 3. 도말층이 덮인군에서 미생물의 부착이 유의성 있게 높았다(P<0.05). 4. 근관 형성중 형성되어 근관 상아질을 덮고 있는 도말층이 미생물의 부착을 증가시켜, 근관 재감염의 기회를 증가시킴을 알 수 있었다.

• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.153-165
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• 2013

The established gait analysis studies have regarded leg as one single spring. If we can design a knee-ankle actuating mechanism as a primary actuator for supporting knee extension, it might be possible to revolutionary store or release elastic strain energy, which is consumed during the gait cycle, and as a result leg stiffness is expected to increase. An ankle joint actuating mechanism that stores and releases the energy in ankle joint is expected to support and solve excessive artificial leg stiffness caused by the knee actuator (primary actuator) to a reasonable extent. If unnecessary kinematic energy is released with the artificial speed reduction control designed to prevent increase in gait speed caused by increase in time passed, it naturally brings question to the effectiveness of the actuator. As opposed to the already established studies, the authors are currently developing knee-ankle two actuator system under the concept of increasing lower limb stiffness by controlling the speed of gait in relative angular velocity of the two segments. Therefore, the author is convinced that compensatory mechanism caused by knee actuating must exist only in ankle joint. Ankle joint compensatory mechanism can be solved by reverse-examining the change in metatarso-phalangeal joint (MTPJ) tilt angle (${\theta}_1=0^{\circ}$, ${\theta}_2=17^{\circ}$, ${\theta}_3=30^{\circ}$) and the effect of change in gait speed on knee activity.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.884-888
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• 2005

An agar-degrading bacterium was isolated from north-eastern sea of Jeju island and cultured in marine agar 2216 media. Biochemical and morphologicl characteristics and 165 rRNA gene revealed that isolated strain was member of Agarivorans genus, and named Agarivorans sp. JA-1. Agarase was produced as growth-related and expressed regardless of agar presence. Optimal pH was 8 at 50 mM Clycine-NaOH buffer, and activity was maximum at $40^{\circ}C$E Enzymatic activity was maintained over $80\%$ at $60^{\circ}C$t and $70\%$ at $80^{\circ}C$ which is thermotolerant. Hence isolated novel Agarivorans sp. JA-1 strain and its beta-agarase could be used for the production of functional oligosaccharide from agar in solution state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.57-60
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• 2003

Electro-Optical (EO) performances for the ion beam (IB) aligned twisted-nematic (TN)-liquid crystal display (LCD) with ion beam exposure on the new of diamond like carbon (DLC) thin film surface were investigated. Voltage-transmittance (V-T) curve and response time without backflow bounce in the ion beam aligned TN-LCD with ion beam exposure for 0.5 and 1min on the DLC thin film was observed. Also. the fast response time of ion beam aligned TN-LCD with ion beam exposure for 1min on the DLC thin film surface can be achieved. The residual DC voltage of the ion beam aligned TN-LCD on the DLC thin film surface was almost the same as that of the rubbing aligned TN-LCD on the polyimide(PI) surface.

• Macromolecular Research
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• v.12 no.2
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• pp.195-205
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• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• Journal of the Korean Electrochemical Society
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• v.11 no.2
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• pp.125-129
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• 2008

Rechargeable lithium-ion polymer batteries have been considered to be next-generation power sources for portable electronic devices and electric vehicles. In this work, we tried to improve the cycling performances of lithium-ion polymer cells by coating aluminum fluoride and acrylonitrile-methyl methacrylate copolymer to the polyethylene separator. It was found that the addition of aluminum fluoride to the surface-modified separator reduced the interfacial resistances and thus the cell exhibited a less capacity fading and better high rate performance. The cell showed an initial discharge capacity of 150 mAh/g and good capacity retention at 0.5 C rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.429-435
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• 2015

A bellows is an important temperature control component in a Joule-Thomson micro-cryocooler. It is designed using a very thin shell, and the inside of the bellows is filled with nitrogen gas. The bellows is made of a nickel-cobalt alloy that maintains its strength and elastic properties in a wide range of temperatures from cryogenic to $300^{\circ}C$. The pressure of the gas and the volume within the bellows vary according to the temperature of the gas. As a result, the bellows contracts or expands in the axial direction like a spring. To explore this phenomenon, the deformation of the bellows and its internal volume must be calculated iteratively under a modified pressure until the state equation of the gas is satisfied at a given temperature. In this paper, the modified Benedict-Webb-Rubin state equation is adopted to describe the temperature-volume-pressure relations of the gas. Experiments were performed to validate the proposed method. The results of a numerical analysis and the experiments showed good agreement.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.359-363
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• 1997

We have investigated the surface characteristics of n-GaAs (100) treated with Ar plasma (40 W, 5~120 sec) by photoreflectance (PR) measurement. With increasing Ar plasma treatment time, the intensity of $E_0$ peak observed to the minimum at 5 sec. The surface electric field ($E_0$), net carrier concentration ($N_P-N_A$), and surface state density ($Q_{SS}$ are $1.05{\times}10^5V/cm$ and $1.31{\tiems}10^{17}cm^{-3}$ and $1.64{\times}10^{-7}C/m^2$, respectively. These values were about 57.1, 81.4 and 56.9% smaller than those of bulk n-GaAs. On the other hand, the concentration of compensation centers ($N_A$) was maximum with value of $5.75{\times}10^{17}cm^{-3}$ at 5 sec. And penetration depth of defects generated after treated with Ar plasma was about 450 $\AA$ from surface.