• Title/Summary/Keyword: Cutting Model

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THE EFFECTS OF DIETARY CONSISTENCY ON THE TRABECULAR BONE ARCHITECTURE IN GROWING MOUSE MANDIBULAR CONDYLE : A STUDY USING MICRO-CONFUTED TOMOGRAPHY (성장 중인 쥐에서 음식물의 경도가 하악 과두의 해면골에 미치는 영향 : 미세전산화 단층촬영을 이용한 연구)

  • Youn, Seok-Hee;Lee, Sang-Dae;Kim, Jung-Wook;Lee, Sang-Hoon;Hahn, Se-Hyun;Kim, Chong-Chul
    • Journal of the korean academy of Pediatric Dentistry
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    • v.31 no.2
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    • pp.228-235
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    • 2004
  • The development and proliferation of the mandibular condyle can be altered by changes in the biomechanical environment of the temporomandibular joint. The biomechanical loads were varied by feeding diets of different consistencies. The purpose of the present study was to determine whether changes of masticatory forces by feeding a soft diet can alter the trabecular bone morphology of the growing mouse mandibular condyle, by means of micro-computed tomography. Thirty-six female, 21 days old, C57BL/6 mice were randomly divided into two groups. Mice in the hard-diet control group were fed standard hard rodent pellets for 8 weeks. The soft-diet group mice were given soft ground diets for 8 weeks and their lower incisors were shortened by cutting with a wire cutter twice a week to reduce incision. After 8 weeks all animals were killed after they were weighed. Following sacrifice, the right mandibular condyle was removed. High spatial resolution tomography was done with a Skyscan Micro-CT 1072. Cross-sections were scanned and three-dimensional images were reconstructed from 2D sections. Morphometric and nonmetric parameters such as bone volume(BV), bone surface(BS), total volume(TV), bone volume fraction(BV/TV), surface to volume ratio(BS/BV), trabecular thickness(Tb. Th.), structure model index(SMI) and degree of anisotropy(DA) were directly determined by means of the software package at the micro-CT system. From directly determined indices the trabecular number(Tb. N.) and trabecular separation(Tb. Sp.) were calculated according to parallel plate model of Parfitt et al.. After micro-tomographic imaging, the samples were decalcified, dehydrated, embedded and sectioned for histological observation. The results were as follow: 1. The bone volume fraction, trabecular thickness(Tb. Th.) and trabecular number(Tb. N.) were significantly decreased in the soft-diet group compared with that of the control group (p<0.05). 2. The trabecular separation(Tb. Sp.) was significantly increased in the soft-diet group(p<0.05). 3. There was no significant differences in the surface to volume ratio(BS/BV), structure model index(SMI) and degree of anisotropy(DA) between the soft-diet group and hard-diet control group (p>0.05). 4. Histological sections showed that the thickness of the proliferative layer and total cartilage thickness were significantly reduced in the soft-diet group.

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Development of a TBM Advance Rate Model and Its Field Application Based on Full-Scale Shield TBM Tunneling Tests in 70 MPa of Artificial Rock Mass (70 MPa급 인공암반 내 실대형 쉴드TBM 굴진실험을 통한 굴진율 모델 및 활용방안 제안)

  • Kim, Jungjoo;Kim, Kyoungyul;Ryu, Heehwan;Hwan, Jung Ju;Hong, Sungyun;Jo, Seonah;Bae, Dusan
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.3
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    • pp.305-313
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    • 2020
  • The use of cable tunnels for electric power transmission as well as their construction in difficult conditions such as in subsea terrains and large overburden areas has increased. So, in order to efficiently operate the small diameter shield TBM (Tunnel Boring Machine), the estimation of advance rate and development of a design model is necessary. However, due to limited scope of survey and face mapping, it is very difficult to match the rock mass characteristics and TBM operational data in order to achieve their mutual relationships and to develop an advance rate model. Also, the working mechanism of previously utilized linear cutting machine is slightly different than the real excavation mechanism owing to the penetration of a number of disc cutters taking place at the same time in the rock mass in conjunction with rotation of the cutterhead. So, in order to suggest the advance rate and machine design models for small diameter TBMs, an EPB (Earth Pressure Balance) shield TBM having 3.54 m diameter cutterhead was manufactured and 19 cases of full-scale tunneling tests were performed each in 87.5 ㎥ volume of artificial rock mass. The relationships between advance rate and machine data were effectively analyzed by performing the tests in homogeneous rock mass with 70 MPa uniaxial compressive strength according to the TBM operational parameters such as thrust force and RPM of cutterhead. The utilization of the recorded penetration depth and torque values in the development of models is more accurate and realistic since they were derived through real excavation mechanism. The relationships between normal force on single disc cutter and penetration depth as well as between normal force and rolling force were suggested in this study. The prediction of advance rate and design of TBM can be performed in rock mass having 70 MPa strength using these relationships. An effort was made to improve the application of the developed model by applying the FPI (Field Penetration Index) concept which can overcome the limitation of 100% RQD (Rock Quality Designation) in artificial rock mass.

A Study on the Application of RTLS Technology for the Automation of Spray-Applied Fire Resistive Covering Work (뿜칠내화피복 작업 자동화시스템을 위한 RTLS 기술 적용에 관한 연구)

  • Kim, Kyoon-Tai
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.5
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    • pp.79-86
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    • 2009
  • In a steel structure, spray-applied fire resistive materials are crucial in preventing structural strength from being weakened in the event of a fire. The quality control of such materials, however, is difficult for manual workers, who can frequently be in short supply. These skilled workers are also very likely to be exposed to environmental hazards. Problems with construction work such as this, which are specifically the difficulty of achieving quality control and the dangerous nature of the work itself, can be solved to some degree by the introduction of automated equipment. It is, however, very difficult to automate the work process, from operation to the selection of a location for the equipment, as the environment of a construction site has not yet been structured to accommodate automation. This is a fundamental study on the possibility of the automation of spray-applied fire resistive coating work. In this study, the linkability of the cutting-edge RTLS to an automation system is reviewed, and a scenario for the automation of spray-applied fire resistive coating work and system composition is presented. The system suggested in this study is still in a conceptual stage, and as such, there are many restrictions still to be resolved. Despite this fact, automation is expected to have good effectiveness in terms of preventing fire from spreading by maintaining a certain level of strength at a high temperature when a fire occurs, as it maintains the thickness of the fire-resistive coating at a specified level, and secures the integrity of the coating with the steel structure, thereby enhancing the fire-resistive performance. It also expected that if future research is conducted in this area in relation to a cutting-edge monitoring TRS, such as the ubiquitous sensor network (USN) and/or building information model (BIM), it will contribute to raising the level of construction automation in Korea, reducing costs through the systematic and efficient management of construction resources, shortening construction periods, and implementing more precise construction

The Effect of Surface Defects on the Cyclic Fatigue Fracture of HEROShaper Ni-Ti rotary files in a Dynamic Model: A Fractographic Analysis (Fractographic 분석을 통한 HEROShaper 니켈티타늄 전동 파일의 피로파절에 미치는 표면결함의 역할)

  • Lee, Jung-Kyu;Kim, Eui-Sung;Kang, Myoung-Whai;Kum, Kee-Yeon
    • Restorative Dentistry and Endodontics
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    • v.32 no.2
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    • pp.130-137
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    • 2007
  • This in vitro study examined the effect of surface defects on cutting blades on the extent of the cyclic fatigue fracture of HEROShaper Ni-Ti rotary files using fractographic analysis of the fractured surfaces. A total of 45 HEROShaper (MicroMega) Ni-Ti rotary flies with a #30/.04 taper were divided into three groups of 15 each. Group 1 contained new HEROShapers without any surface defects. Group 2 contained HEROShapers with manufacturing defects such as metal rollover and machining marks. Croup 3 contained HEROShapers that had been clinically used for the canal preparation of 4-6 molars A fatigue-testing device was designed to allow cyclic tension and compressive stress on the tip of the instrument whilst maintaining similar conditions to those experienced in a clinic. The level of fatigue fracture time was measured using a computer connected the system. Statistical analysis was performed using a Tukey's test. Scanning electron microscopy (SEM) was used for fractographic analysis of the fractured surfaces. The fatigue fracture time between groups 1 and 2, and between groups 1 and 3 was significantly different (p<0.05) but there was no significant difference between groups 2 and 3 (p>0.05). A low magnification SEM views show brittle fracture as the main initial failure mode At higher magnification, the brittle fracture region showed clusters of fatigue striations and a large number of secondary cracks. These fractures typically led to a central region of catastrophic ductile failure. Qualitatively, the ductile fracture region was characterized by the formation of microvoids and dimpling. The fractured surfaces of the HEROShapers in groups 2 and 3 were always associated with pre-existing surface defects. Typically, the fractured surface in the brittle fracture region showed evidence of cleavage (transgranular) facets across the grains, as well as intergranular facets along the grain boundaries. These results show that surface defects on cutting blades of Ni-Ti rotary files might be the preferred sites for the origin of fatigue fracture under experimental conditions. Furthermore this work demonstrates the utility of fractography in evaluating the failure of Ni-Ti rotary flies.

Analysis of Landslide Occurrence Characteristics Based on the Root Cohesion of Vegetation and Flow Direction of Surface Runoff: A Case Study of Landslides in Jecheon-si, Chungcheongbuk-do, South Korea (식생의 뿌리 점착력과 지표유출의 흐름 조건을 고려한 산사태의 발생 특성 분석: 충청북도 제천지역의 사례를 중심으로)

  • Jae-Uk Lee;Yong-Chan Cho;Sukwoo Kim;Minseok Kim;Hyun-Joo Oh
    • Journal of Korean Society of Forest Science
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    • v.112 no.4
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    • pp.426-441
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    • 2023
  • This study investigated the predictive accuracy of a model of landslide displacement in Jecheon-si, where a great number of landslides were triggered by heavy rain on both natural (non-clear-cut) and clear-cut slopes during August 2020. This was accomplished by applying three flow direction methods (single flow direction, SFD; multiple flow direction, MFD; infinite flow direction, IFD) and the degree of root cohesion to an infinite slope stability equation. The application assumed that the soil saturation and any changes in root cohesion occurred following the timber harvest (clear-cutting). In the study area, 830 landslide locations were identified via landslide inventory mapping from satellite images and 25 cm resolution aerial photographs. The results of the landslide modeling comparison showed the accuracy of the models that considered changes in the root cohesion following clear-cutting to be improved by 1.3% to 2.6% when compared with those not considered in the area under the receiver operating characteristics (AUROC) analysis. Furthermore, the accuracy of the models that used the MFD algorithm improved by up to 1.3% when compared with the models that used the other algorithms in the AUROC analysis. These results suggest that the discriminatory application of the root cohesion, which considers changes in the vegetation condition, and the selection of the flow direction method may influence the accuracy of landslide predictive modeling. In the future, the results of this study should be verified by examining the root cohesion and its dynamic changes according to the tree species using the field hydrological monitoring technique.

Transfer and Validation of NIRS Calibration Models for Evaluating Forage Quality in Italian Ryegrass Silages (이탈리안 라이그라스 사일리지의 품질평가를 위한 근적외선분광 (NIRS) 검량식의 이설 및 검증)

  • Cho, Kyu Chae;Park, Hyung Soo;Lee, Sang Hoon;Choi, Jin Hyeok;Seo, Sung;Choi, Gi Jun
    • Journal of Animal Environmental Science
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    • v.18 no.sup
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    • pp.81-90
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    • 2012
  • This study was evaluated high end research grade Near infrared spectrophotometer (NIRS) to low end popular field grade multiple Near infrared spectrophotometer (NIRS) for rapid analysis at forage quality at sight with 241 samples of Italian ryegrass silage during 3 years collected whole country for evaluate accuracy and precision between instruments. Firstly collected and build database high end research grade NIRS using with Unity Scientific Model 2500X (650 nm~2,500 nm) then trim and fit to low end popular field grade NIRS with Unity Scientific Model 1400 (1,400 nm~2,400 nm) then build and create calibration, transfer calibration with special transfer algorithm. The result between instruments was 0.000%~0.343% differences, rapidly analysis for chemical constituents, NDF, ADF, and crude protein, crude ash and fermentation parameter such as moisture, pH and lactic acid, finally forage quality parameter, TDN, DMI, RFV within 5 minutes at sight and the result equivalent with laboratory data. Nevertheless during 3 years collected samples for build calibration was organic samples that make differentiate by local or yearly bases etc. This strongly suggest population evaluation technique needed and constantly update calibration and maintenance calibration to proper handling database accumulation and spread out by knowledgable control laboratory analysis and reflect calibration update such as powerful control center needed for long lasting usage of forage analysis with NIRS at sight. Especially the agriculture products such as forage will continuously changes that made easily find out the changes and update routinely, if not near future NIRS was worthless due to those changes. Many research related NIRS was shortly study not long term study that made not well using NIRS, so the system needed check simple and instantly using with local language supported signal methods Global Distance (GD) and Neighbour Distance (ND) algorithm. Finally the multiple popular field grades instruments should be the same results not only between research grade instruments but also between multiple popular field grade instruments that needed easily transfer calibration and maintenance between instruments via internet networking techniques.

Dynamic Limit and Predatory Pricing Under Uncertainty (불확실성하(不確實性下)의 동태적(動態的) 진입제한(進入制限) 및 약탈가격(掠奪價格) 책정(策定))

  • Yoo, Yoon-ha
    • KDI Journal of Economic Policy
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    • v.13 no.1
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    • pp.151-166
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    • 1991
  • In this paper, a simple game-theoretic entry deterrence model is developed that integrates both limit pricing and predatory pricing. While there have been extensive studies which have dealt with predation and limit pricing separately, no study so far has analyzed these closely related practices in a unified framework. Treating each practice as if it were an independent phenomenon is, of course, an analytical necessity to abstract from complex realities. However, welfare analysis based on such a model may give misleading policy implications. By analyzing limit and predatory pricing within a single framework, this paper attempts to shed some light on the effects of interactions between these two frequently cited tactics of entry deterrence. Another distinctive feature of the paper is that limit and predatory pricing emerge, in equilibrium, as rational, profit maximizing strategies in the model. Until recently, the only conclusion from formal analyses of predatory pricing was that predation is unlikely to take place if every economic agent is assumed to be rational. This conclusion rests upon the argument that predation is costly; that is, it inflicts more losses upon the predator than upon the rival producer, and, therefore, is unlikely to succeed in driving out the rival, who understands that the price cutting, if it ever takes place, must be temporary. Recently several attempts have been made to overcome this modelling difficulty by Kreps and Wilson, Milgram and Roberts, Benoit, Fudenberg and Tirole, and Roberts. With the exception of Roberts, however, these studies, though successful in preserving the rationality of players, still share one serious weakness in that they resort to ad hoc, external constraints in order to generate profit maximizing predation. The present paper uses a highly stylized model of Cournot duopoly and derives the equilibrium predatory strategy without invoking external constraints except the assumption of asymmetrically distributed information. The underlying intuition behind the model can be summarized as follows. Imagine a firm that is considering entry into a monopolist's market but is uncertain about the incumbent firm's cost structure. If the monopolist has low cost, the rival would rather not enter because it would be difficult to compete with an efficient, low-cost firm. If the monopolist has high costs, however, the rival will definitely enter the market because it can make positive profits. In this situation, if the incumbent firm unwittingly produces its monopoly output, the entrant can infer the nature of the monopolist's cost by observing the monopolist's price. Knowing this, the high cost monopolist increases its output level up to what would have been produced by a low cost firm in an effort to conceal its cost condition. This constitutes limit pricing. The same logic applies when there is a rival competitor in the market. Producing a high cost duopoly output is self-revealing and thus to be avoided. Therefore, the firm chooses to produce the low cost duopoly output, consequently inflicting losses to the entrant or rival producer, thus acting in a predatory manner. The policy implications of the analysis are rather mixed. Contrary to the widely accepted hypothesis that predation is, at best, a negative sum game, and thus, a strategy that is unlikely to be played from the outset, this paper concludes that predation can be real occurence by showing that it can arise as an effective profit maximizing strategy. This conclusion alone may imply that the government can play a role in increasing the consumer welfare, say, by banning predation or limit pricing. However, the problem is that it is rather difficult to ascribe any welfare losses to these kinds of entry deterring practices. This difficulty arises from the fact that if the same practices have been adopted by a low cost firm, they could not be called entry-deterring. Moreover, the high cost incumbent in the model is doing exactly what the low cost firm would have done to keep the market to itself. All in all, this paper suggests that a government injunction of limit and predatory pricing should be applied with great care, evaluating each case on its own basis. Hasty generalization may work to the detriment, rather than the enhancement of consumer welfare.

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Implementation of HACCP Model for Steamed Rice with Squid Served from Elementary School with Joint-Lunch Management System (공동관리 초등학교의 안전한 오징어덮밥 생산을 위한 HACCP적용)

  • 박금순;이인숙;금경운
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.33 no.2
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    • pp.365-372
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    • 2004
  • The purpose of this study was to implement HACCP system to foodservice of W and D elementary schools with joint-lunch management system in Kyungsan area. Steamed rice with squid was selected and Control Action, Monitoring Procedure and Control measure were identified based on HACCP flowchart to produce safe and healthy food. It was suggested that frozen squid must be thawed under the cold running city water and kept temperature below 1$0^{\circ}C$ and receiving/thawing procedure has to be done within 30 min. Raw vegetables must be washed under three-tube wash stand and whole prepreparation procedures should be done in 20 minutes. Clean and sanitize all the equipment and utensils before and after handling squid. Knives and cutting boards for vegetable and squid should be classified. Sauce for steamed rice with squid should be heated about 21 minutes to reach the temperature of 94$^{\circ}C$ before serving and internal temperature of food must be kept above 84.4$^{\circ}C$ during serving. The ideal temperature of kitchen should be remained 15∼18$^{\circ}C$. The underground water has to be excluded to minimize the risk of contamination in the foodservice facility and the prepreparation place must be separated with cooking place. Also, Personal hygiene Practice should be check in each stage. Further, additional research needs to be conducted to determine models for HACCP implementation for different menu.

Ultimate Strength tests Considering Stranding Damage (좌초손상을 고려한 최종강도 실험)

  • Lee, T.K.
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.11 no.2
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    • pp.86-91
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    • 2008
  • Ships operating in littoral sea are likely to be subjected to accidental load such as stranding. Once she has damage on the hull structure, her ultimate strength will be reduced. This paper is to investigate the effect of the stranding damage on ultimate strength of ship structure by using a series of collapse tests. For the experiment, 720 mm $\times$720 mm in section and 900mm in length of five box-girder models with stiffeners were pre- pared. Of the five, one has no damage and faur have an diamond shaped damage which represents the shape of rock section in seabed. The damage size is different between models. Among the damaged models, the damages of 3 of them were made by cutting the plate and one by pressing to represent stranding damage. Experiments were carried out under pure bending load and the applied load and displacements were recorded. The ultimate strength is reduced as the damage size increases, as expected. The largest damaged model has the damage size of 30% of breadth and its ultimate strength is reduced by 21% than that of no damaged one. The pressed one has lower ultimate strength than cut one. This might be due to the fact that the plate around the pressed damage area effect negatively on the ultimate strength.

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The Microbiological Assessment of a University Foodservice Establishment, and Hazard Analysis for Quality Control of Fried Fish Cake Soup Preparation (대학 급식시설의 위생 실태조사 및 품질관리를 위한 연구 - 제 1 보 : 오뎅국을 중심으로 -)

  • Rew, Kyung;Kim, Jeong-Mi;Kwak, Tong-Kyung
    • Journal of Nutrition and Health
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    • v.18 no.4
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    • pp.283-292
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    • 1985
  • A sanitary quality of a university foodservice establishment was assessed in terms of time and temperature, pH and Aw, and microbiological evaluation. Critical control points during various phases in product flow of fried fish cake soup were identified using hazard analysis concept. The results are summarized as follows : 1) Time and temperature data indicated that phases of holding ingredients at room temperature after cooking, and hot - holding of soup before assembly were critical. 2) pH and Aw values were in favorable for microbial growth. 3) Microbiological data indicated that microbial quality of ingredients was in poor condition. A holding practice of cooked ingredients at room temperature might provide the chance for microbial contamination and multiplication. Hot - holding time and temperature of soup should be strictly controlled to assure the food safety, since the microbial quality of serving food can be directly influenced by the hot - holding temperature of soup. 4) Microbiological test results for food containers, equipments, working surfaces, and supplies indicated that sanitary conditions of earthenware, gloves, wiping cloths and cutting board should be improved promptly. 5) Critical control points identified were : ingredients, pre - preparation, post - preparation, and holding before assembly and service. 6) Guidelines for the effective quality control program for this operation were suggested.

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