• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.2
• /
• pp.226-233
• /
• 1999

An experimental study has been performed on natural convection heat transfer with a rapid crust formation in the molten metal pool of a low Prandtl number fluid. Two types of steady state tests, a low and high geometric aspect ratio cases in the molten metal pool, were performed. The crust thickness by solidification was measured 88 a function of boundary surface temperatures. The experimental results on the relationship between the Nusselt number and Rayleigh number In the molten metal pool with a crust formation were compared with existing correlations. The experimental study has shown that the bottom surface temperature of the molten metal layer, in all experiments. is the major influential parameter in the crust formation, duo to the natural convection flow. The Nusselt number of the case without a crust formation in the molten metal pool is greater than that of the case with the crust formation at the same Rayleigh number. The present experimental results on the relationship between the Nusselt number and Rayleigh number In the molten metal pool match well with Globe and Dropkin's correlation. From the experimental results, a now correlation between the Nusslet number and Rayleigh number in the molten metal pool with the crust formation was developed as $Nu=0.0923(Ra)^{0.302}$ ($2{\times}10^4< Ra<2{\times}10^7$).

• Publications of The Korean Astronomical Society
• /
• v.26 no.3
• /
• pp.115-127
• /
• 2011

Since the thirteenth century, large scale facilities and various instruments for astronomical observation were built and installed in East Asia. During the Yuan Dynasty, S. ti.ntai (Beijing astronomical observatory in the Yuan Dynasty, 司天臺) was built in Beijing in 1279. Various astronomical instruments, including Ganui (Jianyi, simplified armillary sphere, 簡儀), Yang-yi (upward hemisphere, 仰儀) and Gyupyo (gnomon, 圭表) were installed in this observatory. These astronomical instruments were modified and improved by researchers of the Joseon Dynasty. Ganuidae (Joseon astronomical observatory, 簡儀臺) was built in Gyeongbokgung (or Gyeongbok palace, 景福宮), Seoul. Its scale was 31 Cheok (Korean feet in the Joseon Dynasty, 尺) in height, 47 Cheok in length and 32 Cheok in width. Lee, Cheon (李蕆, 1376~1451), a responsible leader of Ganuidae project, set up various astronomical instruments with his colleagues. Ganui and Jeongbangan (direction-determining board, 正方案) were installed at the top of this observatory. Gyupyo was installed at the west side of this observatory and Honui (armillary sphere, 渾儀) and Honsang (celestial globe, 渾象) were installed in a small pavilion which was located next to Gyupyo. A decade after installation, this observatory was moved to the north-west side of the palace but almost destroyed during Japanese invasion of Korea in 1592 except Ganuidae. We have analyzed documents about Ganuidae and investigated Chinese remains of astronomical observatories and artifacts of astronomical instruments. In this paper, we suggest the appearance, structure, arrangement and scale of Ganuidae, which are expected to be used for the restoration of Ganuidae at some day in the near future.

• Journal of Ocean Engineering and Technology
• /
• v.28 no.2
• /
• pp.160-166
• /
• 2014

Because of industrial development, industrial facilities are becoming more complex and diversified. Plant industries are focused on productivity improvement, cost reduction, and product uniformity by simplifying production processes using automated control. Furthermore, plant industries require higher pressures and temperatures to improve energy efficiency. For this reason, the valves used in plants are operated under harsh conditions. Globe valves and gate valves are mainly used for high pressure these days. However, these valves have various problems, including low maintainability and high cost, due to structural problems. Therefore, butterfly and ball valve applications are increasing in industrial plants. This paper suggests a quadruple-offset butterfly valve that is applicable to bi-direction use, and the principle design parameters are suggested. The selected design parameters are an eccentric flange center line and shaft centerline(Offset 1), an eccentric seat centerline and disc shaft centerline(Offset 2), the angle between the flange centerline and seat wedge angle(Offset 3), the angle between the vertical direction of the disc shaft centerline and seat centerline(Offset 4), and the seat engagement angle. To analyze the interaction effect of the design parameters, ANOM and ANOVA were performed with an orthogonal array. The parameters were found to have effects in the following order: Offset 2, Offset 1, engagement angle, Offset 3, and Offset 4. The interaction between the parameters was insignificant.

• Archives of Craniofacial Surgery
• /
• v.9 no.2
• /
• pp.101-104
• /
• 2008

Purpose: Diplopia and cosmetically unacceptable enophthalmos are the major complications of blow out fracture. Prolapse of orbital tissue into the sinuses, enlarged orbital volume, atrophy of orbital fat and loss of support of orbital walls play a role in the pathogenesis of enophthalmos. To correct post-traumatic enophthalmos, freeing of incarcerated orbital contents combined with reduction of bony orbital volume and reconstruction of suspensory support of globe is necessary. But remained enophthalmos after surgical treatment is difficult to correct completely. In this case, the authors performed implant insertion for affected orbit and endoscopic orbital decompression for unaffected orbit for correction of late enophthalmos. Method: We reviewed a girl patient with right inferomedial orbital wall blow out fracture, right zygoma fracture treated at our hospital for correction of enophthalmos. An 18-year-old female had sustained posttraumatic enopthalmos. Two surgical management was performed for correction blow out fracture at the other hospital. But residual diplopia, enophthalmos, cheek drooping were found. And then she transferred to our hospital. She had severe enophthalmos(5 mm) also had diplopia and extraocular muscle limitation. We performed operation for correction of enophthalmos. After operation, she showed minimal improvement of diplopia and enophthalmos(3 mm). The authors make plan for operation for correction enophthalmos due to cosmetical improvement. Implant insertion was performed for affected orbit. For unaffected orbit, nasoendoscopic medial orbital wall decompression was proceeded. Result: Correction of enophthalmos was found after operation and was maintained for nine years follow-up. Patient expressed satisfaction for the result. Conclusion: To correct persistant enophthalmos, we could have satisfactory result with orbital wall reconstruction on affected eye and decompression on unaffected eye.

• KIEAE Journal
• /
• v.16 no.6
• /
• pp.69-75
• /
• 2016

Climate change has resulted in the urban heat island (UHI) effect throughout the globe, contributing to heat-related illness and fatalities. In order to reduce such damage, it is necessary to improve the climate observation network for precise observation of the urban thermal environment and quick UHI forecasting system. Purpose: This study analyzed the effective range of the climate observation network and the distribution of the existing Automatic Weather Stations (AWS) in Seoul to propose optimal locations for additional installment of AWS. Method: First, we performed quality analysis to pinpoint missing values and outliers within the high-density temperature data measured. With the result from the analysis, a spatial autocorrelation structure in the temperature data was tested to draw the effective range and correlation distance for each major time period. Result: As a result, it turned out that the optimal effective range for the climate observation network in Seoul in July was a radius of 2.8 kilometers. Based on this result, population density, and temperature data, we selected the locations for additional installment of AWS. This study is expected to be used to generate urban temperature maps, select and move measurement locations since it is able to suggest valid, specific spatial ranges when the data measured in point is converted into surface data.

• Journal of the Korean housing association
• /
• v.20 no.3
• /
• pp.1-10
• /
• 2009

The final aim of this study was to propose guidelines for the indoor environment of apartment remodeling projects. The first task of this study was to understand the major elements and the actual condition of the remodeling for apartment unit by carrying out in-depth interviews on residents and specialists. The open-access interviews were conducted with interior designers who have a wide experience of apartment remodeling and residents who live in recently remodeled apartment units. The second task was to evaluate the actual condition of the indoor environment and to analyze the main factors that affect the indoor environment in remodeled apartment units. Field measurements were carried out in twenty apartment units occupied after remodeling, recording indoor environment elements (indoor temperature, globe temperature, relative humidity, $CO_2$, CO, PM10, TVOC, HCHO, illumination, and equivalent noise level). Moreover, resident interviews and researcher observations were carried out to determine the contents of the remodeled unit and to investigate the architectural and living factors(like ventilation characteristics, etc.) related to the indoor environment. The results are as follows. The remodeling elements generally included the changing of lighting fixtures and finishing materials in all the spaces, the integration of the balcony into the children's room, the installation of furniture in the kitchen and the entrance, the changing storage furnitures and equipments in the bathroom. The average levels of each unit of relative humidity, $CO_2$, TVOC, HCHO, equivalent noise level, and illumination were proved to be on the whole in inadequate condition. The factors that affect these indoor elements were classified as remodeling factors (remodeling amounts, extent balcony integration, and lighting fixture exchange), ventilation characteristics, and living factors. According to these results, this research proposed the guidelines for the indoor environment in apartment remodeling projects.

• KIEAE Journal
• /
• v.14 no.1
• /
• pp.91-99
• /
• 2014

Environmental issues have become gradually important around the globe, which has increased society needs for the environment-friendly construction. In an effort to realize the environmental protection and energy efficiency, the British BREEAM has been developed, which is followed by the USA LEED, Japanese CASBEE and other national certification systems based on their own conditions. In this end, the Republic of Korea has implemented its own certification system named GBCS(Green Building Certification System) in 2002, and now actively promoted the G-SEED(Green Standard for Energy and Environmental Design) after GBCS modifications and amendments. The purpose of this study is to identify possible problems to be encountered in the process of the G-SEED for office facilities and to provide relevant solutions. In this end, three office facilities have been selected, which had obtained the G-SEED. This study has analyzed reasons of change of assessment scores between the preliminary certification and the main certification phases, has identified problems through in-depth interviews with practicing professionals(design, construction, eco-friendly consulting firm) and then has reached a conclusion for improvements. This study will be possibly used as reference materials for improvements of the green building certification system, and further detailed studies on respective parts will be required for improvements.

• Korean Journal of Ichthyology
• /
• v.24 no.2
• /
• pp.101-109
• /
• 2012

The egg development and early life history of Acheilognathus macropterus from Japan which is an exotic bitterling from China were observed under the controlled water temperature, $20.0{\pm}1.0^{\circ}C$. Fertilized eggs are opaque yellow in color and long elliptic globe shaped measuring $2.78{\pm}0.12mm$ in length and $1.44{\pm}0.04mm$ in breadth. The number of egg averaged 151 per an oviposition. The eggs of this species began to hatch about seventy eight hours after insemination and the mean of total length of larvae were 3.8 mm. S form moving of larvae were observed from three days after hatching. The larvae reached at the heterotrophic stage about twenty-five days after hatching. Morphological character and analysis of cytochrome DNA of this species from Japan were relatively similar to Korean but spawned egg shape was different remarkably. Taxonomical research is necessary in the future.

• Journal of the Korean Society of Costume
• /
• v.60 no.6
• /
• pp.117-138
• /
• 2010

This study tries to analyse the type of sasanian crowns by looking into the icons and meanings of various motifs that changed the archetype and shape of the crowns, and the social and political factors that affected those motifs. Based on such analysis, the study is aimed at completing the periodic typology of the sasanian crown. For this study the literature research is combined with the empirical analysis of information. Korymbos which symbolizes globe represented the authority and power of the sasanian kings, but the motif with such meaning was replaced by star motif in the late-sasanian crowns. The basic motifs embellishing the sasanian crown represent Gods, which is interpreted as an attempt to symbolize the relations between Gods and kings. These motifs are found on each king's crown in a different and individual way, which seems because the kings at the time chose the motif that can symbolize their own political intention or spirit. At the early days of the sasanian dynasty, Korymbos motif was highly emphasized on the crowns, and was used throughout the end of the dynasty and then was replaced by star motif. From the mid-4th century, Crescent motif started to be used, which was always shown as the shape supporting Korymbos and star motif on it. Bird wing motif was intermittently used in the early and middle days of the dynasty, and was highly emphasized in the crowns of all the kings in the end of the dynasty. Star motif started to be used in the end of sasanian dynasty.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.5
• /
• pp.679-683
• /
• 2013

BSR noise emerges in a vehicle as a result of road vibrations, engine vibrations, and speaker vibrations. BSR noise occurs with an irregular impact or stick slip friction phenomenon as the influence of the resonance mode when the vibration input load is transferred along poor joint and contacting pairs of the system. A sub-structure method of finite element analysis is required to detect impacts and slip in the full vehicle model. This study presents a method for sub-structure modeling and a rattle and squeak detection methodology that considers the characteristics of road vibration inputs.