• 천문학회보
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• 제40권2호
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• pp.34.2-34.2
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• 2015

We aim to investigate the formation of primordial globular clusters (GCs) in the isolated dwarf galaxy (${\sim}10^{10}M_{sun}$) with cosmological zoom-in simulations. For this, we modified cosmological hydrodynamic code, GADGET-3, in a way to include the radiative heating/cooling that enables gas particles cool down to T~10K, reionization (z < 8.9) of the Universe, UV shielding ($n_{shield}$ > $0.014cm^{-3}$), and star formation. Our simulation starts in a cubic box of a side length 1Mpc/h with 17 million particles from z = 49. The mass of each dark matter (DM) and gas particle is $M_{DM}=4.1{\times}10^3M_{sun}$ and $M_{gas}=7.9{\times}10^2M_{sun}$, respectively, thus the GC candidates can be resolved with more than hundreds particles. We found the following results: 1) mini halos with the more interactions before merging into the main halo form the more stars and thus have the higher star mass fraction ($M_{star}/M_{total}$), 2) the mini halos with the high $M_{star}/M_{total}$ can survive longer and thus spiral into closer to the galactic center, 3) the majority of them spiral into bulge, but some of them can survive until the last as baryon-dominated system, like the GC.

• ETRI Journal
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• 제36권1호
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• pp.31-41
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• 2014

The heterogeneous network (HetNet) has been discussed in detail in the Long-Term Evolution (LTE) and LTE Advanced standards. However, the standardization of High-Speed Packet Access HetNet (HSPA HetNet) launched by 3GPP is pushing at full steam. Interference coordination (IC), which is responsible for dealing with the interference in the system, remains a subject worthy of investigation in regard to HSPA HetNet. In this paper, considering the network framework of HSPA HetNet, we propose a quasi-distributed IC (QDIC) scheme to lower the interference level in the co-channel HSPA HetNet. Our QDIC scheme is constructed as slightly different energy-efficient non-cooperative games in the downlink (DL) and uplink (UL) scenarios, respectively. The existence and uniqueness of the equilibrium for these games are first revealed. Then, we derive the closed-form best responses of these games. A feasible implementation is finally developed to achieve our QDIC scheme in the practical DL and UL. Simulation results show the notable benefits of our scheme, which can indeed control the interference level and enhance the system performance.

• 에너지공학
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• 제27권3호
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• pp.48-56
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• 2018

The shell waste biomineralization process has known a tremendous metamorphosis and also the nanostructure with the identification of matrix proteins in oyster shells. However, proteins are represented in minor shell components and they are the major macromolecules that control biocrystal synthesis. Aragonite and calcite were derived from molluscan shells and evaluated the source of carbonate minerals and it helps for the formation of limestone. The oyster shell wastes are large and massive. The paleoecological study of oyster beds has discovered a near-shore and thin Upper Rudeis formation with storm influence during the accumulation of oysters with highly altered by disarticulation, bioerosion, and encrustation. It is possible even in the Paleozoic mollusks provided sufficient carbonate entirely to the source of microcrystalline of limestone. The present review is to discuss paleoecologically a number of oyster shell beds accumulated and sediment to form the different types of limestone during the Middle Miocene time.

• 비파괴검사학회지
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• 제27권3호
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• pp.268-279
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• 2007

The reliability of cold-bonding repair technique of carbon-fiber reinforced plastics (CFRP) laminates, often used as a temporary repair for the airplane maintenance, has been evaluated during cyclic loading and localized heating by nondestructive methods. Major concern was given to the evolution of damage after repair in the form of delaminations due to localized heating and cyclic loading combined. An area of interest both on the specimen repaired by cold-bonding and the specimen without repair where delaminations were induced by localized heating and cyclic loading was monitored by acoustic emission (AE) testing and further examined by pitch-catch low-frequency bond testing, and pulse-echo high-frequency ultrasonic testing. The results showed that the reliability of cold-bonding repair would be significantly reduced by the localized heating and cyclic loading combined rather than by the cyclic loading only. AE monitoring appeared to be an effective and reliable tool to monitor the integrity of temporarily repaired CFRP laminates in terms of the structural health monitoring (SHM) philosophy.

• 한국운동역학회지
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• 제12권2호
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• pp.407-415
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• 2002

Athletic products must meet the needs of athletes and the demands imposed by sports through innovative design. These needs of athletes and requirements of sports are performance, protection and comfort related. In depth knowledge of anatomy and physiology, etiology of commonly reported injuries, and lower extremity mechanics form the basis of product creation/engineering. Game analysis which entails time and frequency surveys of the skills performed during a game, interviews with athletes and coaches, and discussions with medical staffs are used to identify the skills that are critical to the needs of athletes. In lab full biomechanical analyses of these skills and/or physiological responses of the athletes lead to clear functional criterions that serve as guidelines to be met by the design team. The concepts created by the design team are in turns subjected to the same battery of biomechanical analyses. The learning gathered through this pluridisciplinary process is used to further evolve design concepts. The evolution-testing loop is repeated until biomechanical and/or physiological, mechanical and perceptual tests indicate that the design concept meets the established functional design criterions. At that time, the design concepts is ready for manufacturing research and development. Additional biomechanical and physical tests are performed through that phase to confirm that the manufacturing processes preserve the functionality of the design concept. Durability and long term performance of production samples are evaluated through a final three month long weartest program. A rigorous research/testing program is crucial to create and engineer sport products that meet the performance, protection.

• Animal Systematics, Evolution and Diversity
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• 제19권2호
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• pp.217-225
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• 2003

한국산 초파리과의 계통학적 연구의 일환으로, 초파리아속에 속하는 10종을 대상으로 동위효소와 수용성 단백질 분석을 실시하였다. 동위효소와 수용성 단백질 분석결과 D.(D.) angularis와 D.(D.) brachynephros가 유전학적으로 가장 가까운 종이었으며, D.(D.) curvispina와 D.(D.) tsigana 사이는 유전적 거리가 가장 먼 종으로 분석되었다. 그리고. 초파리아속 10종은 D.(D.) virilis, D. (D.) tsigana, D. (D.) lacertosa의 제1군과 D. (D.) angularis와 D. (D.) hrachynephros, D. (D.) unispina와 D. (D.) curvispina, D. (D.) takadai와 D. (D.) kuntzei. 그리고 D (D.) nigromaculata의 4개의 아군으로 이루어진 제 2군으로 나눌 수 있다.

• Animal Systematics, Evolution and Diversity
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• 제13권4호
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• pp.285-290
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• 1997

우리나라의 서해연안에서 채집된 상어류 2개체는 아직까지 국내에서는 보고된 바 없는 Sphyrna lewini(Griffith and Smith)와 Alopias vulpinus(Bonnaterre)로 동정되었다. S. lewini는 귀상어(S. zygaena)와 유사하지만 두부의 중앙부가 함입되엉 있고, 제2등지느러미 끝이 거의 꼬리지느러미에 달한다는 점에서 귀상어와 구분되었다. A. ulpinus는 환도상어(A. pelagicus)와 유사하지만 복부의 흰색이 가슴지느러미 기부 위까지 확장되고, 입의 양쪽 끝에 입술주름이 있어서 환도상어와 구분되었다.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.43-51
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• 2008

Evolutionary Algorithms (EAs) cover all the applications involving the use of Evolutionary Computation in electronic system design. It is largely applied to complex optimization problems. EAs introduce a new idea for automatic design of electronic systems; instead of imagine model, ions, and conventional techniques, it uses search algorithm to design a circuit. In this paper, a method for automatic optimization of the digital circuit design method has been introduced. This method is based on randomized search techniques mimicking natural genetic evolution. The proposed method is an iterative procedure that consists of a constant-size population of individuals, each one encoding a possible solution in a given problem space. The structure of the circuit is encoded into a one-dimensional genotype as represented by a finite string of bits. A number of bit strings is used to represent the wires connection between the level and 7 types of possible logic gates; XOR, XNOR, NAND, NOR, AND, OR, NOT 1, and NOT 2. The structure of gates are arranged in an $m{\times}n$ matrix form in which m is the number of input variables.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2000년도 춘계학술대회
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• pp.154-173
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• 2000

Since computerized numerical controller (CNC) emerged as a result of the fusion of the electronics technology and the mechanical technology, there has been continuous evolution of CNC technology in the mechatronics industry. The industry is recently developing a new control system based on the fusion of personal computer (PC) and CNC. Upgraded PC has now integrated into CNC, making various machines possible to exchange data, software and hardware, and to greatly improve man-machine interface. The fusion of PC and CNC can form a new paradigm in technological innovation of not only control system but also whole machinery industry in near the future. Korea lagged behind the developed countries in the development of open control system with the fusion of PC. Turbo-tek, Hyundai Motor and Daewoo are leading companies, but their commercial possibility seems to be low because domestic market is too small to reap a commercial benefit. Nevertheless, the development of the system is an essential step for Korea to embark on a future technological paradigm of the machinery industry. The government needs to play some role for the development, for instance, government R&D projects, institutional building and training of related technicians.

• Geomechanics and Engineering
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• 제13권2호
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• pp.285-300
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• 2017

Shallow coal resources are increasingly depleted, the mining has entered the deep stage. Due to "High stress, high gas, strong adsorption and low permeability" of coal seam, the gas drainage has become more difficult and the probability of coal and gas outburst accident increases. Based on the flow solid coupling theory of coal seam gas, the coupling model about stress and gas seepage of coal seam was set up by solid module and Darcy module in Comsol Multiphysics. The gas extraction effects were researched after applying hydraulic technology to increase permeability. The results showed that the effective influence radius increases with the expanded borehole radius and drainage time, decreases with initial gas pressure. The relationship between the effective influence radius and various factors presents in the form: $y=a+{\frac{b}{\left(1+{(\frac{x}{x_0})^p}\right)}}$. The effective influence radius with multiple boreholes is obviously larger than that of the single hole. According to the actual coal seam and gas geological conditions, appropriate layout way was selected to achieve the best effect. The field application results are consistent with the simulation results. It is found that the horizontal stress plays a very important role in coal seam drainage effect. The stress distribution change around the drilling hole will lead to the changes in porosity of coal seam, further resulting in permeability evolution and finally gas pressure distribution varies.