• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.192-205
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• 2009

The unexpected wind over the Mt. Hwawang on 9 February 2009 was deadly when many spectators were watching a traditional event to burn dried grasses and the fire went out of control due to the wind. We analyzed the fatal wind based on wind flow simulations over a digitized complex terrain of the mountain with a localized heating area using a three dimensional computational fluid dynamics model, CFD_NIMR_SNU (Computational Fluid Dynamics_National Institute of Meteorological Research_Seoul National University). Three levels of fire intensity were simulated: no fire, $300^{\circ}C$ and $600^{\circ}C$ of surface temperature at the site on fire. The surface heat accelerated vertical wind speed by as much as $0.7\;m\;s^{-1}$ (for $300^{\circ}C$) and $1.1\;m\;s^{-1}$ (for $600^{\circ}C$) at the center of the fire. Turbulent kinetic energy was increased by the heat itself and by the increased mechanical force, which in turn was generated by the thermal convection. The heating together with the complex terrain and strong boundary wind induced the unexpected high wind conditions with turbulence at the mountain. The CFD_NIMR_SNU model provided valuable analysis data to understand the consequences of the fatal mountain fire. It is suggested that the place of fire was calm at the time of the fire setting due to the elevated terrain of the windward side. The suppression of wind was easily reversed when there was fire, which caused updraft of hot air by the fire and the strong boundary wind. The strong boundary wind in conjunction with the fire event caused the strong turbulence, resulting in many fire casualties. The model can be utilized in turbulence forecasting over a small area due to surface fire in conjunction with a mesoscale weather model to help fire prevention at the field.

• Journal of Practical Engineering Education
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• v.15 no.1
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• pp.119-126
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• 2023

Today, in order to improve fuel efficiency and dynamic behavior of automobiles, an era of light weight and simplification of automobile parts is being formed. In order to simplify and design and manufacture the shape of the product, various components are integrated. For example, in order to commercialize three products into one product, product processing is occurring to a very narrow area. In the case of existing parts, precision die casting or casting production is used for processing convenience, and the multi-piece method requires a lot of processes and reduces the precision and strength of the parts. It is very advantageous to manufacture integrally to simplify the processing air and secure the strength of the parts, but if a deep and narrow pocket part needs to be processed, it cannot be processed with the equipment's own spindle. To solve a problem, research on cutting processing is being actively conducted, and multi-axis composite processing technology not only solves this problem. It has many advantages, such as being able to cut into composite shapes that have been difficult to flexibly cut through various processes with one machine tool so far. However, the reality is that expensive equipment increases manufacturing costs and lacks engineers who can operate the machine. In the five-axis cutting processing machine, when producing products with deep and narrow sections, the cycle time increases in product production due to the indirectness of tools, and many problems occur in processing. Therefore, dedicated machine tools and multi-axis composite machines should be used. Alternatively, an angle spindle may be used as a special tool capable of multi-axis composite machining of five or more axes in a three-axis machining center. Various and continuous studies are needed in areas such as processing vibration absorption, low heat generation and operational stability, excellent dimensional stability, and strength securing by using the angle spindle.

• MISULJARYO - National Museum of Korea Art Journal
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• v.97
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• pp.14-54
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• 2020

The overall study of Samsaebulhoedo (painting of the Assembly of Buddhas of Three Ages) at Yongjusa Temple has focused on dating it, analyzing the painting style, identifying its painter, and scrutinizing the related documents. However, its greater coherence could be achieved through additional support from empirical evidence and logical consistency. Recent studies on Samsaebulhoedo at Yongjusa Temple that postulate that the painting could have been produced by a monk-painter in the late nineteenth century and that an original version produced in 1790 could have been retouched by a painter in the 1920s using a Western painting style lack such empirical proof and logic. Although King Jeongjo's son was not yet installed as crown prince, the Samsaebulhoedo at Yongjusa Temple contained a conventional written prayer wishing for a long life for the king, queen, and crown prince: "May his majesty the King live long / May her majesty the Queen live long / May his highness the Crown Prince live long" (主上殿下壽萬歲, 王妃殿下壽萬歲, 世子邸下壽萬歲). Later, this phrase was erased using cinnabar and revised to include unusual content in an exceptional order: "May his majesty the King live long / May his highness the King's Affectionate Mother (Jagung) live long / May her majesty the Queen live long / May his highness the Crown Prince live long" (主上殿下壽萬歲, 慈宮邸下壽萬歲, 王妃殿下壽萬歲, 世子邸下壽萬歲). A comprehensive comparison of the formats and contents in written prayers found on late Joseon Buddhist paintings and a careful analysis of royal liturgy during the reign of King Jeongjo reveal Samsaebulhoedo at Yongjusa Temple to be an original version produced at the time of the founding of Yongjusa Temple in 1790. According to a comparative analysis of formats, iconography, styles, aesthetic sensibilities, and techniques found in Buddhist paintings and paintings by Joseon court painters from the eighteenth and nineteenth centuries, Samsaebulhoedo at Yongjusa Temple bears features characteristic of paintings produced around 1790, which corresponds to the result of analysis on the written prayer. Buddhist paintings created up to the early eighteenth century show deities with their sizes determined by their religious status and a two-dimensional conceptual composition based on the traditional perspective of depicting close objects in the lower section and distant objects above. This Samsaebulhoedo, however, systematically places the Buddhist deities within a threedimensional space constructed by applying a linear perspective. Through the extensive employment of chiaroscuro as found in Western painting, it expresses white highlights and shadows, evoking a feeling that the magnificent world of the Buddhas of the Three Ages actually unfolds in front of viewers. Since the inner order of a linear perspective and the outer illusion of chiaroscuro shading are intimately related to each other, it is difficult to believe that the white highlights were a later addition. Moreover, the creative convergence of highly-developed Western painting style and techniques that is on display in this Samsaebulhoedo could only have been achieved by late-Joseon court painters working during the reign of King Jeongjo, including Kim Hongdo, Yi Myeong-gi, and Kim Deuksin. Deungun, the head monk of Yongjusa Temple, wrote Yongjusa sajeok (History of Yongjusa Temple) by compiling the historical records on the temple that had been transmitted since its founding. In Yongjusa sajeok, Deungun recorded that Kim Hongdo painted Samsaebulhoedo as if it were a historical fact. The Joseon royal court's official records, Ilseongnok (Daily Records of the Royal Court and Important Officials) and Suwonbu jiryeong deungnok (Suwon Construction Records), indicate that Kim Hongdo, Yi Myeong-gi, and Kim Deuksin all served as a supervisor (gamdong) for the production of Buddhist paintings. Since within Joseon's hierarchical administrative system it was considered improper to allow court painters of government position to create Buddhist paintings which had previously been produced by monk-painters, they were appointed as gamdong in name only to avoid a political liability. In reality, court painters were ordered to create Buddhist paintings. During their reigns, King Yeongjo and King Jeongjo summoned the literati painters Jo Yeongseok and Kang Sehwang to serve as gamdong for the production of royal portraits and requested that they paint these portraits as well. Thus, the boundary between the concept of supervision and that of painting occasionally blurred. Supervision did not completely preclude painting, and a gamdong could also serve as a painter. In this light, the historical records in Yongjusa sajeok are not inconsistent with those in Ilseongnok, Suwonbu jiryeong deungnok, and a prayer written by Hwang Deok-sun, which was found inside the canopy in Daeungjeon Hall at Yongjusa Temple. These records provided the same content in different forms as required for their purposes and according to the context. This approach to the Samsaebulhoedo at Yongjusa Temple will lead to a more coherent explanation of dating the painting, analyzing its style, identifying its painter, and interpreting the relevant documents based on empirical grounds and logical consistency.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.145-153
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• 2021

Purpose: The purpose of this study is to evaluate the ovarian dose during radiation therapy for breast cancer in women of childbearing age through an experiment. The ovarian dose is evaluated by comparing and analyzing between the calculated dose in the treatment planning system according to the treatment technique and the measured dose using a thermoluminescence dosimeter (TLD). The clinical usefulness of lead (Pb) apron is investigated through dose analysis according to whether or not it is used. Materials and Methods: Rando humanoid phantom was used for measurement, and wedge filter radiation therapy, 3D conformal radiation therapy, and intensity modulated radiation therapy were used as treatment techniques. A treatment plan was established so that 95% of the prescribed dose could be delivered to the right breast of the Rando humanoid phantom 3D image obtained using the CT simulator. TLD was inserted into the surface and depth of the virtual ovary of the Rando hunmanoid phantom and irradiated with radiation. The measurement location was the center of treatment and the point moved 2 cm to the opposite breast from the center of the Rando hunmanoid phantom, 5cm, 10cm, 12.5cm, 15cm, 17.5cm, 20cm from the boundary of the right breast to the center of treatment and downward, and the surface and depth of the right ovary. Measurements were made at a total of 9 central points. In the dose comparison of treatment planning systems, two wedge filter treatment techniques, three-dimensional conformal radiotherapy, and intensity-modulated radiation therapy were established and compared. Treatments were compared, and dose measurements according to the use of lead apron were compared and analyzed in intensity-modulated radiation therapy. The measured value was calculated by averaging three TLD values for each point and converting using the TLD calibration value, which was calculated as the point dose mean value. In order to compare the treatment plan value with the actual measured value, the absolute dose value was measured and compared at each point (%Diff). Results: At Point A, the center of treatment, a maximum of 201.7cGy was obtained in the treatment planning system, and a maximum of 200.6cGy was obtained in the TLD. In all treatment planning systems, 0cGy was calculated from Point G, which is a point 17.5cm downward from the breast interface. As a result of TLD, a maximum of 2.6cGy was obtained at Point G, and a maximum of 0.9cGy was obtained at Point J, which is the ovarian dose, and the absolute dose was 0.3%~1.3%. The difference in dose according to the use of lead aprons was from a maximum of 2.1cGy to a minimum of 0.1cGy, and the %Diff value was 0.1%~1.1%. Conclusion: In the treatment planning system, the difference in dose according to the three treatment plans did not show a significant difference from 0.85% to 2.45%. In the ovary, the difference between the Rando humanoid phantom's treatment planning system and the actual measured dose was within 0.9%, and the actual measured dose was slightly higher. This did not accurately reflect the effect of scattered radiation in the treatment planning system, and it is thought that the dose of scattered radiation and the dose taken by CBCT with TLD inserted were reflected in the actual measurement. In dosimetry according to the with or without a lead apron, when a lead apron was used, the closer the distance from the treatment range, the more effective the shielding was. Although it is not clinically appropriate for pregnancy or artificial insemination during radiotherapy, the dose irradiated to the ovaries during treatment is not expected to significantly affect the reproductive function of women of childbearing age after radiotherapy. However, since women of childbearing age have constant anxiety, it is thought that psychological stability can be promoted by presenting the data from this study.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.359-371
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• 2008

Purpose: The purpose of this study was to investigate the stress distribution in mandibular implant overdentures with telescopic crowns compared to bar attachment. Material and methods: Three-dimensional finite element models consisting of the mandibular bone, 4 implants, and primary bar-splinted superstructure or secondary splinted superstructure with telescopic crowns were created. Vertical and oblique loads were directed onto the occlusal areas of the superstructures to simulate the maximal intercuspal contacts and working contacts such as group function occlusion. Maximum stress and stress distribution were analysed in mandibular bone, implant abutments, and superstructures. Results: 1. In comparison of von Mises stress on mandibular bone, telescopic overdenture had a little lower stress values in vertical load and working side load except oblique load. In the mandible, the telescopic overdenture distributed more uniform stress than the bar overdenture. 2. In comparison of von Mises stress on implant abutments, telescopic overdenture had much lower stress values in all load conditions. In implant abutments, the telescopic overdenture distributed stress similar to the bar overdenture. Stress was concentrated on the distal surfaces of the posterior implant abutments in both mandibular overdentures. 3. In comparison of von Mises stress on superstructures, the telescopic overdenture had much more stress values in all load conditions. However, the telescopic overdenture distributed more uniform stress on superstructure than the bar overdenture. In the bar overdenture, stress was concentrated on each cental area of bar structures and connected area between implant abutments and bar structures. Conclusion: In the results of this study, the telescopic overdenture had lower stress values than the bar overdenture in mandibular bone and implant abutments, but more stress values in superstructures. However, if optimal material was selected in making superstructures, the telescopic overdenture was compared to the bar overdenture in stress distribution.

• The korean journal of orthodontics
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• v.37 no.6
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• pp.391-399
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• 2007

Three-dimensional approaches for the diagnosis and analysis of the dentofacial area are becoming more popular in accordance with the development of cone-beam CT (CBCT). The purposes of this study were to evaluate the reliability of cephalometric measurements of lateral cephalograms generated from a CBCT image by making comparisons with the traditional digital lateral cephalogram, and to evaluate the possibility of the clinical application of CBCT generated cephalogram images. Methods: Twenty patients whose external auditory meatus could be identified in the CBCT image were selected, and both CBCT and digital cephalograms were taken. Differences between the measurements of both cephalograms were tested by paired t-test. Results: Among the 22 measurements used, only U1-FH, Mx6 to PTV, and maxillomandibular difference showed statistically significant differences between the CBCT generated cephalogram and the digital cephalogram. Conclusions: The results suggest that the CBCT generated cephalogram can be used for some cephalometric measurements not requiring porion, PTV, condylion as a landmark (SNA, SNB, U1 to SN, IMPA, interincisal angle, etc.).

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.235-243
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• 2007

Hepatocellular carcinoma is significant worldwide public health problem with an estimated annually mortality of 1,000,000 people. Radiofrequency (RF) ablation is an interventional technique that in recent years has come to be used for treatment of the hepatocellualr carcinoma, by destructing tumor tissues in high temperatures. Numerous studies have been attempted to prove excellence of RF ablation and to improve its efficiency by various methods. However, the attempts are sometimes paradox to advantages of a minimum invasive characteristic and an operative simplicity in RF ablation. The aim of the current study is, therefore, to suggest an improved RF ablation technique by identifying an optimum RF pattern, which is one of important factors capable of controlling the extent of high temperature region in lossless of the advantages of RF ablation. Three-dimensional finite element (FE) model was developed and validated comparing with the results reported by literature. Four representative Rf patterns (sine, square, exponential, and simulated RF waves), which were corresponding to currents fed during simulated RF ablation, were investigated. Following parameters for each RF pattern were analyzed to identify which is the most optimum in eliminating effectively tumor tissues. 1) maximum temperature, 2) a degree of alteration of maximum temperature in a constant time range (30-40 second), 3) a domain of temperature over $47^{\circ}C$ isothermal temperature (IT), and 4) a domain inducing over 63% cell damage. Here, heat transfer characteristics within the tissues were determined by Bioheat Governing Equation. Developed FE model showed 90-95% accuracy approximately in prediction of maximum temperature and domain of interests achieved during RF ablation. Maximum temperatures for sine, square, exponential, and simulated RF waves were $69.0^{\circ}C,\;66.9^{\circ}C,\;65.4^{\circ}C,\;and\;51.8^{\circ}C$, respectively. While the maximum temperatures were decreased in the constant time range, average time intervals for sine, square, exponential, and simulated RE waves were $0.49{\pm}0.14,\;1.00{\pm}0.00,\;1.65{\pm}0.02,\;and\;1.66{\pm}0.02$ seconds, respectively. Average magnitudes of the decreased maximum temperatures in the time range were $0.45{\pm}0.15^{\circ}C$ for sine wave, $1.93{\pm}0.02^{\circ}C$ for square wave, $2.94{\pm}0.05^{\circ}C$ for exponential wave, and $1.53{\pm}0.06^{\circ}C$ for simulated RF wave. Volumes of temperature domain over $47^{\circ}C$ IT for sine, square, exponential, and simulated RF waves were 1480mm3, 1440mm3, 1380mm3, and 395mm3, respectively. Volumes inducing over 63% cell damage for sine, square, exponential, and simulated RF waves were 114mm3, 62mm3, 17mm3, and 0mm3, respectively. These results support that applying sine wave during RF ablation may be generally the most optimum in destructing effectively tumor tissues, compared with other RF patterns.

• The korean journal of orthodontics
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• v.38 no.5
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• pp.304-313
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• 2008

Objective: The purpose of this study was to evaluate the stress distribution in bone and displacement distribution of the miniscrew according to the length and number of the miniscrews used for the fixation of miniplate, and the direction of orthodontic force. Methods: Four types of finite element models were designed to show various lengths (6 mm, 4 mm) and number (3, 2) of 2 mm diameter miniscrew used for the fixation of six holes for a curvilinear miniplate. A traction force of 4 N was applied at $0^{\circ}$, $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$ to an imaginary axis connecting the two most distal unfixed holes of the miniplate. Results: The smaller the number of the miniscrew and the shorter the length of the miniscrew, the more the maximum von Mises stress in the bone and maximum displacement of the miniscrew increased. Most von Mises stress in the bone was absorbed in the cortical portion rather than in the cancellous portion. The more the angle of the applied force to the imaginary axis increased, the more the maximum von Mises stress in the bone and maximum displacement of the miniscrew increased. The maximum von Mises stress in the bone and maximum displacement of the miniscrew were measured around the most distal screw-fixed area. Condusions: The results suggest that the miniplate system should be positioned in the rigid cortical bone with 3 miniscrews of 2 mm diameter and 6 mm length, and its imaginary axis placed as parallel as possible to the direction of orthodontic force to obtain good primary stability.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.1
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• pp.10-21
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• 2014

This study focuses on the landscape of Daegodae(大孤臺), a prominent rock placed at the side of Namgae Stream in Hamyang, and the person who enjoy the landscape. Through the analysis of the letters such as names carved on the rocks based on ancient poetry and stone walls, the study examines the characteristics of the landscape and the space of Daegodae and the phase of hegemony to enjoy the landscape and space. The result of this study is as follow.2) There are 5 Seowon(書院: lecture halls) nearby Daegodae identified in the ancient map has 5 auditoriums nearby, and three-dimensional volume and eccentricity of the Daegodae is impressive. Daegodae, named by Noh Jin(1518~1578) in 16th century, was used in a variety of ways, including viewing, game, recreation, and meeting, by the staff of the lecture halls including Namgae Seowon(南溪書院), as a result of analyzing the ancient document Go-dae-il-Loc(孤臺日錄) written by Jung Kyung-Woon(鄭慶雲: 1556~?). The structure of Daegodae is that there is Chunggeunchung(淸近亭) on the rock face of the top and Sanangjae(山仰齋) to the west around the memorial stone for Yang Hee(梁喜: 1515~1581). The upper part of the foundation of Daegodae with 11m high and $10m^2$ wide to the east and west was widely used for lecturing and poetry reading. To the north and west of the foundation were the writing of Kim Jeong-Hee(金正喜: 1786~1856) with the words 'Seoksong Chusa(石松 秋史)' carved on the rock and the remains of a dead tree that is presumed to have been called as 'Seoksong'. They are the landscapes that further enhance the history and authenticity of this place. The two kinds of letters carved on the rock 'Daegodae Gaeeunseo(大高臺 介隱書)' and 'Mukheon JungGeunSang(鄭近相: 1893~1934)' were recorded each by Jung Jae-Gi(1811~1879) and his grandson Jung Geun-Sang, which are, as the outcome of exclusive space possession and space hegemony, the signatures indicating that they were the persons who enjoyed this place during the late Joseon and Japanese colonial era. In other words, Daegodae had some implied meaning of preoccupancy of the place as Gujolyangseonsengjangguso since the middle of Joseon, and the place was passed down as a buddhism lecturing and memorial venue called "Dungbukganghoiso Cheonryungjaeseonhyunjangguso" after going through the space hegemony of Jung Jae-Gi and Jung Geun-Sang during the late Joseon and Japanese colonial era each, Nevertheless, a number of letters carved on the rock identified also imply that 'Hadong Jung(河東鄭氏)' and 'Pungcheon Noh(豊川盧氏)' were those who enjoyed the landscape of Daegodae and the center of the space hegemony. The "letters carved on the rock of Daegudae" is another case of cultural landscape and traditional gardening space that serves as the representation of the will of enjoying the landscape in this place and the history of space hegemony.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.149-163
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• 2006

The purpose of this study was to compare the lower extremity's joint and segment coupling patterns between forward and backward running in subjects who were twelve healthy males. Three-dimensional kinematic data were collected with Qualisys system while subjects ran to forward and backward. The thigh internal/external rotation and tibia internal/external rotation, thigh flexion/extension and tibia flexion/extension, tibia internal/external rotation and foot inversion/eversion, knee internal/external rotation and ankle inversion/eversion, knee flexion/extension and ankle inversion/eversion, knee flexion/extension and ankle flexion/extension, and knee flexion/extension and tibia internal/external rotation coupling patterns were determined using a vector coding technique. The comparison for each coupling between forward and backward running were conducted using a dependent, two-tailed t-test at a significant level of .05 for the mean of each of five stride regions, midstance(1l-30%), toe-off(31-50%), swing acceleration(51-70%), swing deceleration(71-90), and heel-strike(91-10%), respectively. 1. The knee flexion/extension and ankle flexion/extension coupling pattern of both foreward and backward running over the stride was converged on a complete coordination. However, the ankle flexion/extension to knee flexion/extension was relatively greater at heel-strike in backward running compared with forward running. At the swing deceleration, backward running was dominantly led by the ankle flexion/extension, but forward running done by the knee flexion/extension. 2. The knee flexion/extension and ankle inversion/eversion coupling pattern for both running was also converged on a complete coordination. At the mid-stance. the ankle movement in the frontal plane was large during forward running, but the knee movement in the sagital plane was large during backward running and vice versa at the swing deceleration. 3. The knee flexion/extension and tibia internal/external rotation coupling while forward and backward run was also centered on the angle of 45 degrees, which indicate a complete coordination. However, tibia internal/external rotation dominated the knee flexion/extension at heel strike phase in forward running and vice versa in backward running. It was diametrically opposed to the swing deceleration for each running. 4. Both running was governed by the ankle movement in the frontal plane across the stride cycle within the knee internal/external rotation and tibia internal/external rotation. The knee internal/external rotation of backward running was greater than that of forward running at the swing deceleration. 5. The tibia internal/external rotation in coupling between the tibia internal/external rotation and foot inversion/eversion was relatively great compared with the foot inversion/eversion over a stride for both running. At heel strike, the tibia internal/external rotation of backward running was shown greater than that of forward(p<.05). 6. The thigh internal/external rotation took the lead for both running in the thigh internal/external rotation and tibia internal/external rotation coupling. In comparison of phase, the thigh internal/external rotation movement at the swing acceleration phase in backward running worked greater in comparison with forward running(p<.05). However, it was greater at the swing deceleration in forward running(p<.05). 7. With the exception of the swing deceleration phase in forward running, the tibia flexion/extension surpassed the thigh flexion/extension across the stride cycle in both running. Analysis of the specific stride phases revealed the forward running had greater tibia flexion/extension movement at the heel strike than backward running(p<.05). In addition, the thigh flexion/extension and tibia flexion/extension coupling displayed almost coordination at the heel strike phase in backward running. On the other hand the thigh flexion/extension of forward running at the swing deceleration phase was greater than the tibia flexion/extension, but it was opposite from backward running. In summary, coupling which were the knee flexion/extension and ankle flexion/extension, the knee flexion/extension and ankle inversion/eversion, the knee internal/external rotation and ankle inversion/eversion, the tibia internal/external rotation and foot inversion/eversion, the thigh internal/external rotation and tibia internal/external rotation, and the thigh flexion/extension and tibia flexion/extension patterns were most similar across the strike cycle in both running, but it showed that coupling patterns in the specific stride phases were different from average point of view between two running types.