• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.154-162
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• 1986

This paper is studied in order to examine eight provinces as Agricultural zone in the early Chosun-Dynasty. The research method of this study depends on discriminant analysis. The research data is obtained from geography of Sejong sillok. In this approach, we believe the possibility of more scientific analysis of agricultural zone. So all cross-sectional data of this period were analysed by means of the discriminant analysis method. In the discriminant analysis of the eight provinces, 54.6% of the country were discriminated. In the territorial map, Kyongsang and Cholla were crossly adjoined and Chungcheong was located in the middle of them. While, Kyonggky and Hwanghae were adjoined in the center, and Pyongan and Hamgil were crossly adjoined, too. And Kangwon was located in the middle of them. Consequently their regional distribution varied widely and the agriculture of this period had considerable regional gaps.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.39-43
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• 2015

This study extends the Distributed Temperature Sensing (DTS) application to delineate the saturated zones in shallow sediment and evaluate the groundwater flow in both downward and upward directions. Dry, partially and fully saturated zones and water level in the subsurface can be recognized from this study. High resolution seepage velocity in vertical direction was estimated from the temperature data in the fully saturated zone. By a single profile, water level can be detected and seepage velocity in saturated zone can be estimated. Furthermore, thermal gradient analysis serves as a new technique to verify unsaturated and saturated zones in the subsurface. The vertical seepage velocity distribution in the recognized saturated zone is then analyzed with improvement of Bredehoeft and Papaopulos' model. This new approach provides promising potential in real-time monitoring of groundwater movement.

• Journal of Korean Neurosurgical Society
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• v.39 no.3
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• pp.231-233
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• 2006

The C2 level is the transition zone between the cranial and cervical spine. Because of its high position and anatomic relationship to vital structures, exposing C2 is challenging and the surgical approach is controversial. We report a of a recurred chordoma in C2 portion, occupying the osseous intraspinal portion. The patient underwent total corpectomy of C3 and gross total removal of tumor by right submandibular approach 3 years previously. We performed a lateral extrapharyngeal approach from contralateral left side with resection C2 central portion followed by gross total removal of mass and placement of graft bone. Although there was transient hypoglossal nerve palsy postoperatively, the patient had full recovery.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.821-826
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• 2001

This paper presents four types of strut-tie model design approaches of structural concrete through the anchorage zone design of a post-tensioned concrete I-beam. The differences and distinctive feature of each approach in terms of structural type of selected strut-tie model, external force acting on strut-tie model, effective strength of concrete strut, and strut-tie model design procedure are analyzed and compared. The outcomes of present study enable structural designers to understand the merits and demerits of each strut-tie model design approach, and thus to conduct reasonable and accurate design of structural concrete.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.2
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• pp.107-112
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• 2001

The prosthodontic treatment of severely resorbed edentulous patients has been one of the frustrating areas due to extensive loss of tissues. The integrated neuromuscular balance among tongue, lip, and cheek is compromised. The retention, stability, and support are the three major factors to influence the clinical outcome. Fish described a denture as having three surface, with each surface playing an independent and important role in the over all fit, stability, and comfort of the denture. He recommended that the polished surface should be a series of inclines so that pressure from muscular activity will retain dentures. Within the denture space there is an area that has been termed the neutral zone. The neutral zone is that area in the mouth where, during function, the forces of the tongue pressing outward are neutralized by the forces of the cheeks and lips pressing inward. According to Jacobson and Krol, neuromuscular control interacts to provide retention and the relationship of polished surface of denture base to the surrounding muscular structure of orofacial capsule facilitates the stability and retention. This neutral zone concept has been demonstrated with various modification by a number of authors. The theory used to develop the denture base contours is based on the belief that the muscle should functionally mold not only the border but the entire polished surface. Lott and Walsh reported the clinical success on complete mandibular dentures with application of neutral zone concept. A number of studies demonstrated that denture stability and retention are more dependent on correct position of the teeth and correct contour of external surfaces of the denture in a severely resorbed alveolar ridge. This article presents a prosthodontic approach to treatment of a edentulous patient using neutral zone technique to improve the retention and stability of the prosthesis.

• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.589-595
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• 2019

The top-seeded solution growth (TSSG) method is an effective approach for the growth of high-quality SiC single crystals. In this method, the temperature gradient in the melt is the key factor determining the crystal growth rate and crystal quality. In this study, the effects of the aperture at the top of the hot-zone on the growth of the SiC single crystal obtained using the TSSG method were evaluated using multiphysics simulations. The temperature distribution and C concentration profile in the Si melt were taken into consideration. The simulation results showed that the adjustment of the aperture at the top of the hot-zone and the temperature gradient in the melt could be finely controlled. The surface morphology, crystal quality, and polytype stability of the grown SiC crystals were investigated using optical microscopy, high-resolution X-ray diffraction, and micro-Raman spectroscopy, respectively. The simulation and experimental results suggested that a small temperature gradient at the crystal-melt interface is suitable for growing high-quality SiC single crystals via the TSSG method.

• Journal of the Korean Society of Safety
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• v.31 no.2
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• pp.26-32
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• 2016

In previous studies on LPG siting in Korea, the scope have not included the probability of the secondary events of adjacent LPG tanks or structures from an explosion source. Therefore, it is essential to first identify the phenomenon which can be caused by BLEVE and then, properly assess their effects to each target including secondary event. In this study, we calculated the effects from a potential BLEVE of 15 ton LPG tank causing damages of storage tanks (LPG), structures and human using Phast ver. 6.7 and then suggested three risk zones (Zone I, II, III) assuming the consequences such as overpressure, heat radiation and missile effect by fragments. Zone I and II are divided at the line of 50% occurrence of the secondary event. Zone II and III are divided by Individual Risk(IR). The zone approach in this study can be used for more effective and safer Land Use Planning (LUP) for the future.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.932-937
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• 2012

In the presented study, SM45C carbon steel parts were joined by friction welding. The welding process was carried out under optimized conditions using statistical approach. The study of SM45C is conducted with various combinations of process parameters. Parameter optimization, microstructure and mechanical property correlation are the major contribution of the study. The welded joints were produced by varying spindle revolution speed, friction pressure, upset pressure and burn-off length. Tension tests were applied to welded parts to obtain the strength of the joints. Fracturs properties were additionally obtained experimentally under fluctuated tensile loads. Microstructures using microphotographs were examined in the weld interface and weld region and heat affected zone and base metal and flash zone of welded parts. Finally, Hardness variations in welding zone and base metal were also obtained. Through these tests, the optimum conditions of parameters for ${\phi}20$ SM45C in friction welding were obtained when the friction spindle revolution was 1,950 rpm, the friction pressures was 30 MPs, upset pressures was 50 MPs.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.945-948
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• 2006

Chloride penetration into concrete is a hot issue of concern all over the world, notwithstanding, very few attempts have been conducted to explore the effect of cracks on choride penetration. Cracks provoke to lose a main function of watertightness of concrete and lead to reduce the service life of concrete. For this reason, it is necessary to define a critical crack width to prevent a quick chloride penetration through crack. In this study, experiment is focused on establishing a critical crack width in terms of chloride penetration. Concrete specimens with different crack widths I crack lengths have been subjected to rapid chloride migration testing. In a side of analytical solution, a simple approach to quantify the chloride diffusion coefficient of only crack zone excluding sound concrete was proposed. The result clearly showed a critical crack width of 0.03 mm. Based on the experimental results, a phenomenological model was proposed to explain the meaning of critical crack width in practical engineering. In this model, cracked concrete zone was divided into three zones. These zones corresponded to a wide crack, a zone with micro-cracks and an uncracked zone.

• Journal of Soil and Groundwater Environment
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• v.8 no.3
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• pp.13-22
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• 2003

Laboratory scale study for an air injection and flowing aspect of groundwater saturated zone was conducted for three sediment grains (AMG 0.34, 1.38, 3.89 mm diameter). Air flow for AMG (Average Modal diameter Grains) 0.34 mm diameter grain size provides indication of pattern of channelized air flow in saturated zone and expansion state in above saturated zone. Maximum area of influence is approximately l5.2%/$\textrm{m}^2$for AMG of 0.34 mm diameter. For AMG of 1.38 mm and 3.89 mm modal diameter grains, air flow are pervasive air flow, forming a symmetrical cone of influence around the injection point. Maximum areas affected are 37%/$\textrm{m}^2$for AMG 1.38 mm diameter and 30%/$\textrm{m}^2$for AMG 3.89 mm diameter. AMG 1.38 mm and 3.89 mm diameter grains show onset of collapse and approach to steady state in above saturated zone, respectively. In this study, optimal sites for in situ air sparging, may be grain diameters between about AMG 1.5-2.5 mm diameter.