• Structural Engineering and Mechanics
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• 제81권2호
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• pp.243-258
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• 2022

In this paper, tensile behavior of joint filling has been investigated under experimental test and numerical simulation (particle flow code). Two concrete slabs containing semi cylinder hole were prepared. These slabs were attached to each other by glue and one cubic specimen with dimension of 19 cm×15 cm×6 cm was prepared. This sample placed in the universal testing machine where the direct tensile stress can be applied to this specimen by implementing a special type of load transferring device which converts the applied compressive load to that of the tensile during the test. In the present work, two different joint filling thickness i.e., 3 mm and 6 mm were prepared and tested in the laboratory to measure their direct tensile strengths. Concurrent with experimental test, numerical simulation was performed to investigate the effect of hole diameter, length of edge notch, filling thickness and filling length on the tensile behavior of joint filling. Model dimension was 19 cm×15 cm. hole diameter was change in four different values of 2.5 cm, 5 cm, 7.5 cm and 10 cm. glue lengths were different based on the hole diameter, i.e., 12.5 cm for hole diameter of 2.5 cm, 10 cm for hole diameter of 5 cm, 7.5 cm for hole diameter of 7.5 cm and 5 cm for hole diameter of 10 cm. length of edge notch were changed in three different value i.e., 10%, 30% and 50% of glue length. Filling thickness were changed in three different value of 3 mm, 6 mm and 9 mm. Tensile strengths of glue and concrete were 2.37 MPa and 6.4 MPa, respectively. The load was applied at a constant rate of 1 kg/s. Results shows that hole diameter, length of edge notch, filling thickness and filling length have important effect on the tensile behavior of joint filling. In fixed glue thinks and fixed joint length, the tensile strength was decreased by increasing the hole diameter. Comparing the results showed that the strength, failure mechanism and fracture patterns obtained numerically and experimentally were similar for both cases.

• 대한치과교정학회지
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• 제32권2호통권91호
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• pp.143-153
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• 2002

콤포지트와 여러가닥 강선을 사용하여 제작된 접착식 보정장치는 심미적이며, 효과적인 보정장치라 할 수 있다. 이 연구는 접착식 보정장치의 전단접착강도를 측정하고, 접착식 보정장치의 제작 시 사용하는 여러가닥 강선 및 접착방법의 이상적인 조합을 제시하기 위해 디자인되었다. 교정치료를 위해 발거한 건전한 상하악 소구치 160개를 사용하여 80개의 시편을 제작하였다. 접착면적 및 강선의 길이, 콤포지트의 두께를 동일화하고, 직접접착 및 간접접착의 방법으로 여러가닥 강선을 접착하여 접착식 보정장치를 제작하였다. 만능시험기를 사용하여 각 시편에서의 전단접착강도 및 강선의 탈락시까지의 신장량을 측정하여, 다음과 같은 결론을 얻었다. 1. 6가닥, 0.0155인치의 강선에서 가장 큰 최대 접착강도를 보이고, 3가닥, 0.0195인치의 강선에서 가장 작은 최대 접착강도를 보였는데, 그 차이는 유의할 만큼 크지 않았다(p<0.05). 즉 강선의 직경 및 가닥수는 접착강도와 큰 연관성이 없다. 2. 3가닥, 0.015인치의 강선에서 가장 큰 신장량을 보여 주었고, 3가닥, 0.0195인치 강선에서 가장 작은 신장량을 보여주었다(p<0.05). 강선의 직경이 작을수록 신장량은 크게 나타났으나, 강선의 가닥수는 신장량과 큰 연관성이 없다. 3. 두 가지 접착방법의 비교에서 간접 접착술식을 사용했을 때 더 큰 접착강도 및 신장량을 보여 주었고, 통계적으로 유의한 차이를 나타냈다(p<0.05).

• 한국가금학회지
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• 제13권2호
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• pp.167-172
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• 1986

본 연구는 단관백백레그혼순계 염색체의 형태적 특징과 크기를 명확히 구명하기 위하여 중심입지수, 등 완비 및 상대적 길이를 측정하여 이용하고 이들의 염색체 수를 밝혔다. 시험재료로서는 서울대학교 부속목장에서 사육중인 단관백색레그혼순계 암컷 20수와 수컷 5수를 공시하고 이들을 수정시켜 50개의 수정란에 대하여 염색체 분석을 하였다. 분석방법으로서는 중기상의 포착을 위하여 colchicine을 이용하고, hypotonic, fixation, air-drying 처리를 하여 나타난 초기 metaphase상으로서 핵형분석하였다. 시험 결과 분석된 각 염색체의 형태적 특징은 다음과 같다. 1. 1,2심 염색체 : meta 및 submetacentric으로서 이들 둘 간에는 크기에 따라 명확히 구분된다. 2. 3,4심 염색체 : 길이는 서로 비슷하나, 4심 염색체에서는 짧은 단완이 나타나고, 3심은 acrocentric 형태이다. 3. 5심 염색체 : 성염색체(Z)로서 metacentric 형태이다. W 염색체 역시 metacentric 이지만 7-8심 염색체 크기 정도이다. 4. 6심 염색체 : 3심과 같이 acro 형체이나 3심 염색체 크기의 반정도이다. 5. 7,8심 염색체 : 6심 크기의 반정도로서 길이는 서로 비슷하나 7심은 짧은 단완을 가지고, 8심은 acrocentric 염색체이다. 6. 9심 염색체 : 7심과 8심의 크기와 비슷하나 metacentric 양상이다. 7. 나머지 30쌍의 소형염색체 : 점의 형태로서 대부분 acrocentric 형태이다. 이 밖에도 염색체의 수에 있어서 관찰된 sample의 58%가 78개로 나타났고, 나머지는 72-77개로 나타남에 따라 이의 염색체 수는 최소 78개로 사료된다.

• Journal of Communications and Networks
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• 제14권5호
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• pp.481-486
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• 2012

Accurate and efficient estimation of the number of sources is critical for providing the parameter of targets in problems of array signal processing and blind source separation among other such problems. When conventional estimators work in unfavorable scenarios, e.g., at low signal-to-noise ratio (SNR), with a small number of snapshots, or for sources with a different strength, it is challenging to maintain good performance. In this paper, the detection limit of the minimum description length (MDL) estimator and the signal strength required for reliable detection are first discussed. Though a comparison, we analyze the reason that performances of classical estimators deteriorate completely in unfavorable scenarios. After discussing the limiting distribution of eigenvalues of the sample covariance matrix, we propose a new approach for estimating the number of sources which is based on a sequential hypothesis test. The new estimator performs better in unfavorable scenarios and is consistent in the traditional asymptotic sense. Finally, numerical evaluations indicate that the proposed estimator performs well when compared with other traditional estimators at low SNR and in the finite sample size case, especially when weak signals are superimposed on the strong signals.

• 한국도로학회논문집
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• 제15권2호
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• pp.131-138
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• 2013

PURPOSES : The intents of the study are to identify the accident factors and to demonstrate the potentials of tobit model as a tool to study the number of accidents on arterial roads segments. METHODS : This paper uses a tobit regression as a methodology to analyze the factors affecting the number of accidents. In pursuing the above goal, this study gives particular attentions to analyzing the data of 2,446 accidents (1,610 in major arterial roads and 836 in minor arterial roads) occurred on arterial roads in 2007 to 2010. RESULTS : First, 3 accident models which were classified by total arterial roads, major arterial roads and minor arterial roads, and were all statistically significant were developed. Second, the exclusive right-turn lane as common variable, and the number of accident, traffic volume, number of lanes, link length, rate of median, number of entrances, number of pedestrian crossings, number of curves, number of bus stops and exclusive left-turn as specific variables of the models were selected. Finally, the paired sample t-test could not be rejected the null hypotheses of three types of models. CONCLUSIONS : Using data from vehicle accidents on arterial roads, the estimation results show that many factors related to roadway geometrics and traffic characteristics significantly affect to the number of accidents.

• 한국멀티미디어학회논문지
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• 제22권2호
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• pp.299-310
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• 2019

Most web documents are written in Cartesian coordinates, so the study of vertical arrangement of text has been well organized, while the study of circular arrangement is very early. With the recent development of circular display devices, the demand for circular arrangement of texts is increasing. Thus, we proposed a CSS3 extended specification of polar coordinate layout for the circular placement of text. First, we defined the concept of fan model for the text arrangement in polar coordinate which is corresponding to box model in Cartesian coordinate. And, we described new definition on the directions of sentence, paragraph and text orientation in polar coordinate. Based on this new definitions, we developed the extended specification consisting of three parts. A part for setting the fan model, a part for setting directions, and a part for setting typesetting properties. To verify the feasibility of the proposed specification in current web browsers, a preprocessor was developed and sample contents were examined. We compared the code length of the sample contents implemented using other JavaScript library CssWarp.js so as to verify the efficiency of the proposed specification.

• 한국컴퓨터정보학회논문지
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• 제23권12호
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• pp.171-177
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• 2018

Purpose : This study is conducted to research the attitude of social workers toward withdrawing life sustaining treatment and compare and analyze the different types of their attitudes. Methods : Research design of this study is Q methodology approach. The study population is 23 social workers. Q sample to investigate the attitude of social workers toward withdrawing life sustaining treatment included 30 statements. After listening to the purpose and method of the study, the 23 social workers agreed to fill out a survey asking sociodemographic information and have been forced to be distributed in 9 scale Q-sample. Results : The collected data was processed through QUANL PC program, sorted into 3 types as followings. The first type was 'the pursuit of quality of life' that the quality of life is more important than the length of life, the second 'choosing to withdraw life sustaining treatment' that they want to write or encourage family to write advanced directive, the third 'withholding life sustaining treatment' regardless of the cost. Conclusion : In conclusion, the social workers attitudes toward withdrawing life sustaining treatment were grouped as three different types, the first type was 'the pursuit of quality of life', the second 'choosing to withdraw life sustaining treatment', the third 'withholding life sustaining treatment'.

• 한국전기전자재료학회논문지
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• 제30권1호
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• pp.27-31
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• 2017

In this study, the effect of Tb inward diffusion on the magnetic properties of the Nd-Fe-B sintered magnets was studied. After sintering of the magnets, $TbF_3$ slurries were dip-coated on the surface of the samples, then heat-treatment was followed for $TbF_3$ diffusion. The element distribution in the magnets and the diffusion profiles of Tb ions were analyzed by an EPMA (electron probe micro-analyzer). Prolonged heat treatment resulted in a deeper diffusion length of Tb ions. Coercivity of the $1^{st}$ heat-treated sample showed 21.86 kOe, while that of the $1^{st}$, $2^{nd}$ heat-treated and annealed sample revealed 34 kOe.

• The Korean Journal of Legal Medicine
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• 제42권4호
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• pp.126-140
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• 2018

The diagnosis of cause of death (COD) or estimation of postmortem interval (PMI) is hard to perform using postmortem blood or other bodily fluids due to various biochemical changes that occur during the agonal phase or after death. To solve these problems, new paradigms and new analytical methods are needed. In this study, postmortem blood was fractionated with specific gravity 1.021, 1.029, 1.038, and 1.045, and the absorbance patterns of each sample of the 131 total cases (12 kinds of COD) were analyzed using a spectrometer. The absorbance was grouped into 9 patterns (ABS pattern 1 to 9) according to the wave length and the signal intensity. These patterns of postmortem blood were found to be distinctly different from the absorbance pattern of fresh blood. The analysis of ABS patterns is useful for the diagnosis of deaths due to acute or rapid bleeding, fire death, drowning and, in some cases, poisoning, but is not useful for the estimation of PMI.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1136-1139
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• 2002

The circular cavity resonator which can measure the dielectric properties of dielectrics in the Ka-band(26.5GHz~40GHz) frequency range was designed and fabricated. A structure of the resonator is divided into two equal parts of the length and the dielectric plate sample is placed between two halves. Exciting and detecting of the resonator is performed by WR28 rectangular waveguides using Bethe's small hole coupling. The GaAs plate sample, whose permittivity is known to be 13 in millimeter wave range, was used for the verification of the performance of the fabricated circular cavity resonator. In the measurement of GaAs single crystal using that resonator, the resonant frequency of the dominant $TE_{011}$ mode, the permittivity and $Q{\times}f_0$ were measured as 26.69GHz, 12.9 and 124,000GHz, respectively.