• Journal of Welding and Joining
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• 제12권3호
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• pp.109-117
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• 1994

Spot welding has wide used with a high work efficiency in the automotive and aerospace industries. Up to the present, the technique mainly used to test spot welds on production lines has been entirely depended upon destructive chisel or peel testing. Therefore, it's being very important assignment to secure the NDE technique which can be evaluate spot weld quality with more efficiency and high reliability. This paper discusses the feasibility of UNDE techniques to evaluate spot weld quality. For the sake of the approach to the quantitative measurement of nugget diameter and the discrimination of a the corona bond from nugget, ultrasonic c-scan image and distribution of reflective echo amplitude was measured by immersion method with the mechanical and the electronic scanning of point-focussed ultrasonic beam(25 MHz). As the results of this study, corona bond which is the most dangerous types of interface defects can be successfully detected, as well as expulsion and voids. Ultrasonic testing results were confirmed and compared by optical microscope and SAM(Scanning Acoustic Microscope) observation of the spot-weld cross section. The results show that the nugget diameter can be successfully measured with the accuracy of 0.8 mm.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.458-468
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• 1996

The Oil Palm industry has developed tremendously with the increasing of planted area from 54,000 hectaresin 1960 to about 2.28 million hectares in 1995. This is expected to increase further to 2.5 million hectares by the year 2000. However, there has been an increasing difficulty in obtaining sufficient labour for the oil palm plantations. At present , harvesting of oil palm fresh fruit is facing an acute shortage of workforce as the workers are much more attracted to the better working environment and salary in the industrial sector. Harvesting of short palm is easily done by using a chisel attached to a short steel pole. Cutting is done by moving the tool at high speed to the target. The weight of the tool coupled with the speed of throwing will produce enough energy to cut the bunch stalk. In this cutting method, sharpness of the cutting device, weight of tool and the speed of throwing contribute to the efficiency of the tool . For the tall palms, a sickle attached to a ong pole is used and the job is more difficult compared to the short palms. Lifting of pole and cutting jobs require great effort and skills. This paper describes the basic design needs in developing an appropriate device that is practical for field use. A prototype design was developed and tested.

• 한국치위생학회지
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• 제2권2호
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• pp.159-173
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• 2002

The 180 toothbrushes out of 18 models( ten brushes for each model) were used for this examination among the toothbrushes for adults which were sold in the domestic markets. After three-month brushings through a roll ing method and Bass method were practiced with Toothbrush Stroke Tester which reproduced brushing methods outside the mouth, I investigated the morphology bristle tips of using scanning electron microscope(SEM). The conclusions are as follows. 1. Soft bristle toothbrushes(of 8 models out of 9 models) were badly damaged at the bristles end after 3 month toothbrushing. 2. Medium bristle toothbrushes(of four models out of five models) were irregularly worn at the bristles end after 3 month toothbrushing. 3. Hard bristle toothbrushes(of three models out of four models) were chisel-shapedly worn at the bristles end after 3 month toothbrushing. 4. Taper-shaped toothbrushes were very irregularly bent at the bristles end after 3 month toothbrushing. 5. It was examined in the bristle stiffness that soft bristle toothbrushes were found in 9 models(50.00%), medium bristle toothbrushes in 5 models(27.78%), and hard-bristle toothbrushes in 4 models(22.22%).

• Restorative Dentistry and Endodontics
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• 제10권1호
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• pp.161-168
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• 1984

The purpose of this study was to examine the effect of heat generated by rotating bur on the dental hard tissue in vitro. Freshly extracted molar teeth with normal appearance from early 20's male were collected and experimental teeth were divided into 4 groups and the teeth in each group were prepared class I cavity with different clinical procedures as follows. The four methods were. I. 20,000rpm without coolant II. 20,000rpm with coolant III. 500,000rpm without coolant IV. 500,000rpm with coolant Five teeth were reserved intact as a control group. These teeth were longitudinally split into two parts by means of chisel after class I cavity preparation. In a control group 5 parts were boiled in water for 20 minutes and the other 5 specimens were not boiled. All specimens were immersed in 2% methylene blue dye solution and the image of dye penetration was examined and photographed under stereomicroscope. Followings were the results obtained through the study. 1. In control group, dye penetration of the unboiled specimens was increased than with the boiled group. 2. The specimens prepared cavity without coolant showed decreased dye penetration than with the coolant group. 3. 20,000rpm without coolant group showed the least dye penetration. 4. 500,000rpm with coolant group showed similar level of dye penetration to the unboiled specimens from the control group.

• 한국임상수의학회지
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• 제36권5호
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• pp.292-295
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• 2019

A 2-year-old, 440 kg, thoroughbred gelding showed a lameness grade of 3 out of 5, as well as swelling and heating on the proximal interphalangeal joint (PIPJ). Periarticular new bones due to the arthritis were observed on performing radiography and ultrasonography. PIPJ arthrodesis was performed under general anesthesia. With the PIPJ open, the articular cartilage was removed by using curette, chisel, and mallet. Arthrodesis was performed with a PIP plate and two additional transarticular cortex screws inserted in lag fashion. A cast was placed over the limb distal from the proximal metatarsal bone. At 6 months after surgery, complete union of the PIPJ was confirmed by radiography, and the incision site was well closed. Based on the outcome, a PIP plate with two additional transarticular cortex screws inserted in lag fashion is recommended as a method for treating osteoarthritis of the PIPJ in horses.

• 대한치과의사협회지
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• 제58권5호
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• pp.276-283
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• 2020

Objectives: The aim of this study was to evaluate the efficacy of CK files as an ultrasonic instrument, and to determine most efficient file size for smear layer removal. Materials and Methods: Thirty-six extracted human mandibular premolars with single, straight root canals and mature apices were mechanically prepared and randomly divided into three groups. Group 1 (Control) underwent conventional needle irrigation, Group 2 (CKS) underwent passive ultrasonic irrigation with a #20 CK file, and Group 3 (CKL) underwent passive ultrasonic irrigation with a #30 CK file. After preparation and irrigation, all teeth were dried and split with a chisel to obtain the mesial and distal half of their roots. Each sample was evaluated using a scanning electron microscope, and data were analyzed using the Kruskal-Wallis and Mann-Whitney rank sum tests (p<0.05). Results: The CKS group showed less debris in the apical third than the other groups (p<0.05). In this section, no significant difference was observed among the other groups. And, there was no significant difference among any groups for the middle third section. Conclusion: This study showed that PUI with #20 CK file removed more smear layer compared to using #30 CK file at the apical third of the root canal.

• Journal of Periodontal and Implant Science
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• 제25권2호
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• pp.357-371
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• 1995

The purpose of this study was to observe the effect of $TGF-{\beta}1$ on the regeneration of bone in guided bone regeneration. Four adult dogs aged 12 to 24 months were used in this study. Experimental bone defects were created surgically with surgical bur and chisel on the 3th. premolars. In experimental group, bone defect were grafted with DFDB and $TGF-{\beta}1$. In control groups, bone defects were grafted with only DFDB. At 1,2,3 and 4 weeks, dogs were serially sacrificed and specimens were prepared with Hematoxylin-Eosin stain and Goldner's stain for light microsopic evaluation. The results of this study were as follows: 1. The infiltration of inflammatory cells was prominent in control groups at 1, 2 and 3 weeks. 2. The lining of osteoblast was observed at 2 weeks in control group, but at 1 week in experimental group. 3. In both groups, osteoid was formed at 2 weeks. In control groups, osteoid was fromed on only bone surface. but in experimental groups, osteoid were formed on both bone & DFDB surfaces. 4. In only experimental groups, The fusion of new bone & DFDB was only observed at 3 weeks. and the fusion of new bone & DFDG was more prominent at 4 weeks. But in control groups, No fusion of new bone& DFDB was oberved at 3 and 4weeks. From the above result, the $TGF-{\beta}1$ was effective in bone formation and increased inductive effect of DFDB in guided bone regeneration technique. Inductive effect of DFDB was increased with $TGF-{\beta}1$.

• 대한두개안면성형외과학회지
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• 제20권6호
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• pp.421-424
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• 2019

Osteomas are benign, slow-growing osteogenic lesions frequently found in the craniomaxillofacial region. They can be classified as peripheral, central, or extraskeletal. Reactive mechanisms to trauma or infection, as well as muscle traction, are thought to play a major role in the development of peripheral osteomas. In the present report, a 41-year-old woman presented with a slowgrowing, painless mass on her left eyebrow. She had suffered trauma 15 years prior. In the computed tomography scan, a 2.5×2×0.7-cm radio-opaque tumor was detected just medial to the left supraorbital foramen, and a peripheral osteoma was clinically diagnosed. An elective operation under general anesthesia was planned. Following a suprabrow incision, subcutaneous and intramuscular dissection was performed. In the surgical plane deep to the corrugator muscles and superficial to periosteum, a branch of the supratrochlear nerve was encountered and preserved using a vessel loop. The osteoma beneath the periosteum was extracted in multiple fragments using a chisel and mallet to minimize trauma to the nerve. Contour and facial symmetry were corrected. To use a suprabrow incision, the surgeon must understand neighboring anatomical structures, including the course of the supratrochlear and supraorbital neurovascular bundles. When these structures are located adjacent to tumor lesions, careful surgical maneuvers should be performed to preserve them.

• Restorative Dentistry and Endodontics
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• 제17권2호
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• pp.365-382
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• 1992

The purpose of this study was to evaluate the adaptation of filling material to the dentinal walls of root canals with and without smear layer. Fifty extracted upper and lower anterior teeth were selected, and the root canals were instrumented with K - files 1mm short of the apical foramen by step - back method. The teeth were randomly divided into two groups of 25 each : in the group I, smear layers were not removed, and in the group II, smear layers were removed by 15% EDTA solution. Again the two groups 25 teeth were randomly divided into unfilled contol group and filling groups(lateral, ultrasonic, ULTRAFIL, McSpadden compaction group). Upon completion of root canal filling, the teeth were grooved on the both the labial and lingual surfaces and then split with mallet and chisel. Each specimens were examined with JSM - 840 Scanning Electron Microscope (JEOL., Japan). The results were as follows : 1. In the contol group, dentinal tubules of group I couldn't be distinguished in the canal wall, but those of group II appeared to be open and patent. 2. In the filling groups of group I, the tubular penetration of the sealer or gutta percha couldn't be seen, but in the filling groups of group II, it could be seen except McSpadden compaction group. 3. In the filling groups, ULTRAFIL group showed the best adaptation of filling material to root canal wall among the group I, and lateral and ultrasonic condensation group showed the best adaptation of filling material among the group II. McSpadden compaction group showed the worst adaptation in group I, II. 4. Generally, the group II showed better adapation of filling material to root canal wall than the group I.

• Journal of the Korean Wood Science and Technology
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• 제46권3호
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• pp.260-269
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• 2018

경산 임당 유적에서 출토된 2-4세기로 추정되는 목제유물의 표면에 존재하는 도구흔적을 분석하여 목제유물의 제작도구와 제작방법을 해석하고자 하였다. 97점의 목제유물의 표면에 존재하는 도구흔적을 분석한 결과, 이들 유물의 제작에 자귀, 끌, 송곳, 손칼, 도끼 등 다양한 도구가 이용되었음이 확인되었다. 특히 갈이틀과 갈이칼의 흔적이 확인됨으로써, 이 시기에 선삭가공 방법이 사용되었음을 알 수 있었다. 또한 선삭가공으로 용기류 목제유물 제작 시 눈질과 선질을 혼합하여 사용했음이 확인되었다. 이는 제작하고자 하는 용기류 목제유물의 형태 및 용도에 따라 적합한 가공방법을 적용한 것으로 판단된다.