• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2524-2533
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• 2024

When analyzing containment thermal-hydraulics, computational fluid dynamics (CFD) is a powerful tool because multi-dimensional and local analysis is required for some accident scenarios. According to the previous study, neglecting steam bulk condensation in the CFD analysis leads to a significant error in boundary layer profiles. Validating the condensation model requires the experimental data near the condensing surface, however, available boundary layer data is quite limited. It is also important to confirm whether the heat and mass transfer analogy (HMTA) is still valid in the presence of bulk condensation. In this study, the boundary layer measurements on the vertical condensing surface in the presence of air were performed with the rectangular channel facility WINCS, which was designed to measure the velocity, temperature, and concentration boundary layers. We set the laminar flow condition and varied the Richardson number (1.0-23) and the steam volume fraction (0.35-0.57). The experimental results were used to validate CFD analysis and HMTA models. For the former, we implemented a bulk condensation model assuming local thermal equilibrium into the CFD code and confirmed its validity. For the latter, we validated the HMTA-based correlations, confirming that the mixed convection correlation reasonably predicted the sum of wall and bulk condensation rates.

• Journal of Korean Society of Rural Planning
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• v.10 no.1 s.22
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• pp.9-17
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• 2004

For the problems in executing rural development, recent recognitions are that discovery, preservation, and utilization of area-unique resource are unsatisfactory, that participation of local residents was neglected, and that approach to gradual refurbishment of houses and common space of town in consideration of existing spatial pattern of the town was not adequate. Especially, neglect for exact investigation, analysis and evaluation on rural local resources is bringing about social problems such as mass production of uniform rural area and loss of local identity. In this study, rural resources were listed and resource evaluation items was designed in order to establish development direction of rural village. According to these results, for the efficient and reasonable drive of the resource evaluation system, following items are required; A premise of local development by participation of local people, Development of diversely appliable resource evaluation clauses, Establishment of development type in connection with resource evaluation clauses, Systematic management of local resource through spreading DB resource. This research was loused on unearthing direction development of rural village and theme. However, what should be reconsidered through continuous study is that resource evaluation clauses are somewhat general and not concretely illustrated. Therefore establishment of characterized development is expected through clarifying local identity and presenting direction of local development, with the importance of resource and systematic analysis in planning on rural village in the future.

• Archives of Craniofacial Surgery
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• v.11 no.2
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• pp.107-110
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• 2010

Purpose: Chondroid syringoma is a rare mixed tumor of the skin that was first described by Hirsch and Helwig (1961). Characteristically, it is composed of the proliferation of epithelial cells in a myxoid and chondroid matrix. Most lesions occur on the head and neck region, and their size may range from 0.5~3 cm. Since a chondroid syringoma presents similar characteristics to other masses on the head and neck region, it is significantly important to distinguish with other masses by a surgical biopsy. Methods: A 51-year old woman presented with a painless nodular mass ($0.5{\times}0.5{\times}0.5cm$) on the philtrum, which appeared during the previous year. The mass was treated with a laser without a surgical biopsy. However, the size of the mass showed no changes. Surgical excision under local anesthesia was performed and sent for histopathology. Results: Gross examination showed a mass surrounded by a well developed capsule within the dermal layer. After complete excision without injury to the orbicularis oris muscle, the wound was covered with a local flap. The histology examination revealed numerous cuboid epithelial cells with tuboalveolar structures and keratinous cysts within a chondroid stroma. No recurrence or metastasis was observed at the follow-up visits. Conclusion: Chondroid syringoma is a rare mass on the face. An accurate diagnosis is essential for optimal treatment. This paper reports a case of a chondroid syringoma on the philtrum with a brief review of the relevant literature.

• Smart Structures and Systems
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• v.13 no.2
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• pp.203-217
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• 2014

Due to the shift in paradigm from passive control to adaptive control, smart tuned mass dampers (STMDs) have received considerable attention for vibration control in tall buildings and bridges. STMDs are superior to tuned mass dampers (TMDs) in reducing the response of the primary structure. Unlike TMDs, STMDs are capable of accommodating the changes in primary structure properties, due to damage or deterioration, by tuning in real time based on a local feedback. In this paper, a novel adaptive-length pendulum (ALP) damper is developed and experimentally verified. Length of the pendulum is adjusted in real time using a shape memory alloy (SMA) wire actuator. This can be achieved in two ways i) by changing the amount of current in the SMA wire actuator or ii) by changing the effective length of current carrying SMA wire. Using an instantaneous frequency tracking algorithm, the dominant frequency of the structure can be tracked from a local feedback signal, then the length of pendulum is adjusted to match the dominant frequency. Effectiveness of the proposed ALP-STMD mechanism, combined with the STFT frequency tracking control algorithm, is verified experimentally on a prototype two-storey shear frame. It has been observed through experimental studies that the ALP-STMD absorbs most of the input energy associated in the vicinity of tuned frequency of the pendulum damper. The reduction of storey displacements up to 80 % when subjected to forced excitation (harmonic and chirp-signal) and a faster decay rate during free vibration is observed in the experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.6
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• pp.569-580
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• 2005

The present study investigates the convective heat/mass transfer characteristics in wavy ducts of a primary surface heat exchanger. The effects of duct aspect ratio and flow velocity on the heat/mass transfer are investigated. Local heat/mass transfer coefficients on the corrugated duct sidewall are determined using a naphthalene sublimation technique. The aspect ratios of the wavy duct are 7.3, 4.7 and 1.8 with the corrugation angle of $145\Omega$. The Reynolds numbers, based on the duct hydraulic diameter, vary from 300 to 3,000. The results show that at the low Re(Re $\leq$ 1000) the secondary vortices called Taylor-Gortler vortices perpendicular to the main flow direction are generated due to effect of duct curvature. By these secondary vortices, non-uniform heat/mass transfer coefficients distributions appear. As the aspect ratio decreases, the number of cells formed by secondary vortices are reduced and secondary vortices and comer vortices mix due to decreased aspect ratio at Re$\leq$1000. At Re >1000, the effects of corner vortices become stronger. The average Sh for the aspect ratio of 7.3 and 4.7 are almost same. But at the small aspect ratio of 1.8, the average Sh decreases due to decreased aspect ratio. More pumping power (pressure loss) is required for the larger aspect ratio due to the higher flow instability.

• Journal of Veterinary Clinics
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• v.40 no.4
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• pp.283-287
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• 2023

A 10-year-old spayed female beagle dog presented with a 2-month history of third-eyelid elevation in the left eye (OS). Ophthalmic examination revealed slightly diminished corneal and palpebral reflexes along with exophthalmos in the OS. Schirmer's tear test and intraocular pressure values were within the normal range for the OS. Slit-lamp biomicroscopy revealed protrusion of the third eyelid and corneal opacity in the OS. Fundoscopy revealed a prominent black mass in the OS covering the optic nerve. Tapetal hyper-reflectivity was also observed around the mass. Ocular ultrasonography showed a 0.74 × 0.67 cm echogenic posterior segment mass around the optic nerve protruding into the retrobulbar space. Computed tomography revealed a contrast-enhanced soft tissue lesion in the posteromedial aspect of the left eyeball protruding into the retrobulbar region, and the optic nerve was suspected to be involved. No evidence of osteolytic changes in the adjacent bone or distant metastasis was observed. Enucleation was performed to prevent potential metastasis or local invasion of the mass and to relieve discomfort due to exposure to keratopathy resulting from lagophthalmos. Histopathological examination revealed a central choroidal melanocytoma extending into the optic nerve. No local recurrence was detected until 16 months postoperatively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.478-487
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• 1991

In this study, dynamic stability of discontinuous free Timoshenko beam, barring a concentrated mass, under constant follower force is considered. Governing differential equations are derived based on the extended Hamilton's principle and finite element method is applied for numerical analysis. Conclusions of the study are as follows : (1) Without force direction control, (i) the critical follower force at instability is increased with concentrated mass regardless of discontinuity. (ii) the minimum critical follower force is located in the vicinity of discontinuity position .xi.$_{d}$=0.75. (iii) at mass location .mu. .leq.0.5 the force at instability is decreased as magnitude of concentrated mass is increased but, at .mu. .geq. 0.5 the force is increased as the mass is increased. (2) With force direction control, (i) shear deformation parameter S contributes insignificantly to the force at instability when S>10$^{[-993]}$ (ii) maximum critical follower force can be obtained for the discontinuity location .xi.$_{d}$=0.25. (iii) the critical follower force is increased as magnitude of concentrated mass .alpha. is increased at mass location .mu. .geq.0.4, but is increased, .mu ..leq.0.4.4.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1147-1154
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• 2006

An experimental investigation was conducted to enhance the heat/mass transfer for impingement/effusion cooling system when the initial crossflow was formed. For the improvement of heat transfer, the circular guide is installed on the injection hole. At the fixed jet Reynolds number of 10,000, the measurements were carried out for blowing ratios ranging from 0.5 to 1.5. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. The result presents that the circular guide protects the injected jet from the initial crossflow, increasing the heat/mass transfer. The heat transfer of stagnation region is hardly changed regardless of the blowing ratio. The secondary peak is obviously formed by flow transition to turbulent flow. At high blowing ratio of 1.5, the circular guide produces $26{\sim}30%$ augmentation on the averaged heat/mass transfer while the case without circular guide leads to the low and non-uniform heat/mass transfer. With the increased heat/mass transfer, the installation of circular guide is accompanied by the increase of pressure loss in the channel. However, the pressure drop caused by the circular guide is lower than that for other cooling technique with the circular pin fin.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.61.1-61.1
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• 2016

Black hole (BH) mass is a fundamental quantity to understand BH growth, galaxy evolution, and connection between them. Thus, obtaining accurate and precise BH mass estimates over cosmic time is of paramount importance. The rest-frame UV CIV ${\lambda}1549$ broad emission line is commonly used for BH mass estimates in high-redshift AGNs (i.e., $2{\leq}z{\leq}5$) when single-epoch (SE) optical spectra are available. Achieving correct and accurate calibration for CIV-based SE BH mass estimators against the most reliable reverberation-mapping based BH mass estimates is thus practically important and still useful. By performing multi-component spectral decomposition analysis to obtained high-quality HST UV spectra for the updated sample of local reverberation-mapped AGNs including new HST STIS observations, CIV emission line widths and continuum luminosities are consistently measured. Using a Bayesian hierarchical model with MCMC sampling based on Hamiltonian Monte Carlo algorithm (Stan NUTS), we provide the most consistent and accurate calibration of CIV-based BH mass estimators for the three line width characterizations, i.e., full width at half maximum (FWHM), line dispersion (${\sigma}_{line}$), and mean absolute deviation (MAD), in the extended BH mass dynamic range of log $M_{BH}/M_{\odot}=6.5-9.1$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1606-1615
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• 2001

The present study has been conducted to investigate heat/mass transfer characteristics on a target plate fur arrays of circular impingement jets with and without effusion holes. A naphthalene sublimation method is employed to determine local heat/mass transfer coefficients on the target plate. The effusion holes are located at the center of four injection holes in the injection plate where the spent air is discharged through the effusion hole after impingement on the target plate. For the array jet impingement without effusion holes, the array jets are injected into the crossflow formed by upstream spent air because the impinged jets must flow to the open exit. For small gap distances, heat/mass transfer coefficients without effusion holes are very non-uniform due to crossflow effects and re-entrainments of spent air. However, uniform distributions and enhanced values of heat/mass transfer coefficients are obtained by installing the effusion holes. For large gap distances, the crossflow has little influence on heat/mass transfer characteristics on the target palate due to the large cross-sectional open area between the injection and target plates. Therefore, the distributions and levels of heat/mass transfer coefficients are almost the same for both cases.