• Restorative Dentistry and Endodontics
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• 제12권1호
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• pp.65-76
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• 1986

Carious dentin can be classified, on the basis of their clinical characteristics, into three groups; sound, sclerotic and active carious dentin. Active carious dentin differs from sclerotic dentin by its abscence of variable bacteria within tubles and amount of chemical content. But the apatite molecules of active carious dentin are not fully studied. The purpose of this study was to observed the physico-chemical characteristics of deep carious dentin. The samples of sound, sclerotic and active carious dentin were obtained respectively from 300 freshly extracted carious teeth. Bacterial-rich zone of superficial soft dentin layer was removed with hand instruments from all samples in advance. The samples were powdered and sieved (200 mesh) before analyses. Identification and estimation of the crystallinity of the samples were carried with X-ray diffraction and infrared absorption analyses. Measurements were made on a Rigaku Denki (Rigaku, geiger flex III, Japan) X-ray diffractometer with Cu-target at 30 Kv, 30 mA and are traced on a monochromatic tracer. Infrared absorption analysis was made on FT-IR spectrophometer (Nicolet Instrument Co.) using KBr pellets containing the samples and was recorded on data process (Model IR-80. Nicolet Instrument, Co). The following conclusions were as follows; 1. The nature of the main inorganic structure of sound, sclerotic and active carious dentin proved to be hydroxyapatite. 2. It was difficult to determine the identification due to their crystallinity of sound, sclerotic and active carious dentin. But sound dentin was the highest in crystallinity among them. 3. The magnesium whitlockite was to be found in active carious dentin, but not in sound and sclerotic dentin. 4. The carbonate content was highest in sound dentin, but the lowest was in active carious dentin.

• 한국지반공학회논문집
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• 제21권7호
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• pp.21-29
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• 2005

본 논문에서는 압축성이 큰 지반 위에 시공되는 지오그리드 보강 계단형 블록식 보강토 옹벽의 거동 특성에 관한 내용을 다루었다. 대상옹벽으로는 2단으로 시공되는 높이 lOrn의 블록식 보강토 옹벽을 고려하였으며 압축성이 큰 지반위에 시공되는 경우를 고려하였다. 본 연구는 검증된 유한요소해석 모델을 사용하여 수행되었으며 기초지반의 침하가 옹벽의 변위 및 보강재 유발 인장력에 미치는 영향을 집중적으로 다루었다. 연구결과 시공중 발생하는 기초지반의 과다 침하는 옹벽의 변위 뿐 아니라 보강재 유발 인장력 또한 현저히 증가시켜 내·외적 안정성에 지대한 영향을 미치는 것으로 나타났다. 본 논문에서는 연구결과와 아울러 실무적 관점에서의 고려사항 을 기술하였다.

• Journal of Yeungnam Medical Science
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• 제2권1호
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• pp.23-30
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• 1985

Keloids are abnormally healed skin wounds that develop in the subpapillary layer of the dermis. They are a lesion with wide, raised and deep scars. They exceed the original dimensions of the wound and grow mounds upon mounds of collagen in a pseudotumor fashion. Their treatment may take several forms such as surgery, intralesional injection of steroid, compression, superficial irradiation, and combination therapy. However, absolute method is nothing until now. Recently, the cryosurgery shows relatively good effect in treatment, so we tried the clinical experience with cryosurgery in the treatment of keloids. Material and methods: During the past 2 years, we treated 20 individuals of the keloids with severe itching and pain. The age ranged from 5 to 45 years old. Only 6 cases were biopsied before and after cryotherapy. The cryosurgery set we used was Toitu model CR 201 $N_2O$ gas (tip temperature is $-80^{\circ}C$) and was applied directly on the lesion about 4 to 5 minutes with slight compression. After cryosurgery in keloids, the following results were obtained: 1. It is both quick and easy method. 2. It causes little or no pain and no loss of blood. 3. Integumentary normalization is rapid. The new scar tissue is smaller, and more elastic and soft. 4. The pain, itching and paresthesia commonly associated with keloid is usually disappeared. 5. Other treatment can be used after cryosurgery. 6. Histologic picture after cryosurgery is similar with the result of steroid injection. 7. The mechanism of the cryosurgery in keloids is the result of the direct tissue destroying action and cryoimmunologic reaction.

• 한국지반공학회논문집
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• 제27권11호
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• pp.17-25
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• 2011

본 연구는 모래로 부분치환된 점토지반 위의 줄기초의 지지력 특성에 대한 것이다. 극한 지지력을 구하기 위해 FEM해석을 사용하였으며 부분치환은 기초의 폭의 비와 양단의 경사로 정의 하였다. B'=inf인 경우는 모래층이 점토층과 같은 반무한체인 경우로 이 때의 극한 지지력이 부분치환된 지반에서의 극한 지지력과 비교를 위해 사용하였다. 지지력 효율 ${\beta}$는 B'=inf인 경우의 극한 지지력과 부분치환에 의한 극한 지지력의 비로 모래로 부분치환된 점토지반의 지지력 특성을 파악하기 위해 사용하였다. 각각 3가지의 점토의 비배수 전단강도와 모래의 내부마찰각을 고려하였다. 분석결과 부분치환 시의 지지력효율 ${\beta}$에 가장 큰 요인은 치환깊이이다.

• ALGAE
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• 제21권2호
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• pp.209-216
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• 2006

The characteristics of Peyssonnelia capensis Montagne (Peyssonneliaceae, Rhodophyta) from Jeju Island were investigated in order to clarify the species entity and re-evaluate taxonomic position. The morphological variations of the Peyssonnelia capensis from Jeju Island were divided into two types, the thin thallus type and the thick thallus type. The thin thallus type is characterized by thin, soft, orbicular, slightly lobed thallus with entire to undulate margin, and compact rhizoids. The thick thallus type has thick and stiff thallus with sinuate margin and scattered rhizoids, and has more branches than the thin thallus type. The basal layer and the epithallium of thin thallus type are similar to those of thick thallus types in their structure. However, the hypothallial cells of the thick thallus type are longer than those of the thin thallus type. The erect filament of thick thallus type has more cells than those of the thin thallus type. Tetrasporangial nemathecia are distinctly protruded. Mature tetrasporangia of this species are divided cruciately into four spores as those of other Peyssonneliaceae. In addition to their morphological and anatomical distinctness between two types, the nucleotide sequence analyses of SSU and ITS2 region make no differences among populations from Jeju and other localities in Korea. Therefore these two morphological variation may not base on genetic variation.

• 대한치과보철학회지
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• 제57권1호
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• pp.88-94
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• 2019

심미적 치료에 대한 요구가 늘어나면서 높은 강도와 심미성을 갖는 지르코니아의 요구도 증가하고 있다. 이러한 흐름에 비추어 지르코니아의 생체적 합성을 평가하는 것은 중요한 일이다. 이번 논문에서는 지르코니아의 생체적합성에 대한 in vivo 실험에 대한 문헌 연구를 진행하였다. In vivo 실험에서 연조직, 경조직에 대한 지르코니아의 생체적합성을 확인할 수 있었다. 다양한 실험동물 및 환자에서 진행된 연구의 대다수에서 지르코니아의 높은 생체적합성이 보고되었으며, 신생골 합성 및 골부착의 면에서 티타늄과 유사한 성질을 보였다. 한편, 지르코니아는 임플란트로도 활용할 수 있다. 임플란트로 활용하기 위해 HA (hydroxyapatite)를 처리하여 생체활성을 높이는 다양한 방식이 제안되고 있다. 하지만 기존의 티타늄 임플란트에 HA를 코팅하는 방식은 낮은 결합강도 및 HA의 변성으로 인한 문제점이 있었기 때문에 HA-지르코니아 composite, HA-coated 지르코니아, HA-지르코니아 functionally graded material (FGM) 또는 알루미나 개재 HA-지르코니아 등의 새로운 방식이 연구되고 있다. 이러한 방식들은 보다 높은 결합강도를 지니고 있으며, 높은 생체적합성을 보여주고 있다.

• Structural Engineering and Mechanics
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• 제83권3호
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• pp.327-340
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• 2022

The Collapse Margin Ratio (CMR) is a notable index used for seismic assessment of the structures. As proposed by FEMA P695, a set of analyses including the Nonlinear Static Analysis (NSA), Incremental Dynamic Analysis (IDA), together with Fragility Analysis, which are typically time-taking and computationally unaffordable, need to be conducted, so that the CMR could be obtained. To address this issue and to achieve a quick and efficient method to estimate the CMR, the Artificial Neural Network (ANN), Response Surface Method (RSM), and Adaptive Neuro-Fuzzy Inference System (ANFIS) will be introduced in the current research. Accordingly, using the NSA results, an attempt was made to find a fast and efficient approach to derive the CMR. To this end, 5016 IDA analyses based on FEMA P695 methodology on 114 various Reinforced Concrete (RC) frames with 1 to 12 stories have been carried out. In this respect, five parameters have been used as the independent and desired inputs of the systems. On the other hand, the CMR is regarded as the output of the systems. Accordingly, a double hidden layer neural network with Levenberg-Marquardt training and learning algorithm was taken into account. Moreover, in the RSM approach, the quadratic system incorporating 20 parameters was implemented. Correspondingly, the Analysis of Variance (ANOVA) has been employed to discuss the results taken from the developed model. Additionally, the essential parameters and interactions are extracted, and input parameters are sorted according to their importance. Moreover, the ANFIS using Takagi-Sugeno fuzzy system was employed. Finally, all methods were compared, and the effective parameters and associated relationships were extracted. In contrast to the other approaches, the ANFIS provided the best efficiency and high accuracy with the minimum desired errors. Comparatively, it was obtained that the ANN method is more effective than the RSM and has a higher regression coefficient and lower statistical errors.

• 한국측량학회지
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• 제40권2호
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• pp.109-118
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• 2022

싱크홀 탐사 등 지반조사를 위한 기술로 개발된 GPR (Ground Penetrating Radar)은 지하시설물 탐사에서 불탐구간을 해소하기 위한 방법으로 한정되어 사용하고 있었다. 정부는 지하시설물 데이터의 정확도 개선을 위하여 2022년 7월부터 비금속 관로 탐사기를 이용한 지하시설물 탐사가 가능하도록 하였다. 그러나 GPR은 점토층 등과 같이 연약지반 같은 수분함량이 높은 지반에서 탐사율도 낮아지고, 정확도에 많은 변동이 발생하는 문제점을 가지고 있다. 본 연구에서는 GPR의 특성과 지하시설물의 환경을 고려한 탐사정확도 향상방안으로 유전률 상수 보정과 GPR 영상자료의 패턴분석을 이용한 지하시설물 GPR탐사 방안을 제시하고자 한다. 본 연구를 통하여 GPR 주파수 대역과 이기종 GPR을 적용한 현장검증 결과 지하시설물 탐사의 정확도 향상 및 높은 재현성 결과를 도출하였다.

• Steel and Composite Structures
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• 제39권4호
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• pp.401-417
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• 2021

This study experimentally reveals the influence of welding on grade S690Q high strength steel (HSS) butt joints from both micro and macro levels. Total eight butt joints, taking plate thickness and welding heat input as principal factors, were welded by shielded metal arc welding. In micro level, the microstructure transformations of the coarse grain heat affected zone (CGHAZ), the fine grain heat affected zone (FGHAZ) and the tempering zone occurred during welding were observed under light optical microscopy, and the corresponding mechanical performance of those areas were explored by micro-hardness tests. In macro level, standard tensile tests were conducted to investigate the impacts of welding on tensile behaviour of S690Q HSS butt joints. The test results showed that the main microstructure of S690Q HSS before welding was tempered martensite. After welding, the original microstructure was transformed to granular bainite in the CGHAZ, and to ferrite and cementite in the FGHAZ. For the tempering zone, some temper martensite decomposed to ferrite. The performed micro-hardness tests revealed that an obvious "soft layer" occurred in HAZ, and the HAZ size increased as the heat input increased. However, under the same level of heat input, the HAZ size decreased as the plate thickness increased. Subsequent coupon tensile tests found that all joints eventually failed within the HAZ with reduced tensile strength when compared with the base material. Similar to the size of the HAZ, the reduction of tensile strength increased as the welding heat input increased but decreased as the thickness of the plate increased.

• 대한두경부종양학회지
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• 제38권2호
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• pp.29-32
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• 2022

Lipoma is one of the most common benign soft tissue tumors. However, giant lipomas compressing and deforming the neurovascular structure rarely occur in the lateral neck. A 70-year-old man visited our outpatient clinic for treatment of a visible painless neck mass that had been identified 2 years prior. Neck magnetic resonance imaging revealed that a 10 × 9 × 4 cm fatty mass located between the sternocleidomastoid and sternohyoid muscles invaded the carotid sheath. Under general anesthesia, the mass was excised without damage to the adjacent neurovascular structures. Upon histopathological examination, the mass was identified as a lipoma. During the surgery, enlargement of the internal jugular vein was observed under the resected mass. However, on ultrasound examination, the function of the internal jugular vein was evaluated as good. No recurrence or neurological and vascular complications were reported during a 6-month follow-up after the surgery. As a giant lipoma located in the deep layer of the lateral neck can deform important cervical structures, its impact on the surrounding structures should be carefully assessed preoperatively to minimize the rate of possible complications.