• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.234-243
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• 1992

Fatigue crack initiation life has a wide scatter and this makes the fatigue design of structural members difficult. In order to make the fatigue life distribution clear, it is required to prepare a large number of specimens and repeat the fatigue tests under the same loading condition. Such fatigue tests usually take much time and cost. In this study, a fatigue testing method using a multi-notched test specimen for the purpose of estimating the distribution function of fatigue crack initiation life by small number of fatigue tests is used. The purpose of this study is to verify the above fatigue testing method of a multi-notched specimen by using Bayesian reliability analysis, Least square method and Skewness method for the determination of unknown Weibull parameters. The multi-notched specimen is a specimen in which several tens of statistically identical notches are prepared.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.63-67
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• 2016

In this paper, we present an indirect method of elastic modulus measurement for various lamination layers formed on polymer-based compliant substrates. Although the elastic modulus of every component is crucial for mechanically reliable microelectronic devices, it is difficult to accurately measure the film properties because the lamination layers are hardly detached from the substrate. In order to resolve the problem, 3-point bending test is conducted with a film-substrate specimen and area transformation rule is applied to the cross-sectional area of the film region. With known substrate modulus, a modulus ratio between the film and the substrate is calculated using bending stiffness of the multilayered specimen obtained from the 3-point bending test. This method is verified using electroplated copper specimens with two types of film-substrate structure; double-sided film and single sided film. Also, common dielectric layers, prepreg (PPG) and dry film solder resist (DF SR), are measured with the double-sided specimen type. The results of copper (110.3 GPa), PPG (22.3 GPa), DF SR (5.0 GPa) were measured with high precision.

• Journal of Aerospace System Engineering
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• v.16 no.2
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• pp.49-62
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• 2022

The purpose of this paper was to present a model analysis-based design process and verification results for the high-lift control system of aircraft. For this, we used Matlab/Simulink, one of the most widely-used physical modeling tools. The high-lift control system can be divided into three domains. (i.e., Electronic control domain, Hydraulic actuation domain, and Mechanical power transmission domain) Based on this division, we modeled each of the major domains and sub-components, and integrated them to complete the complicated system model. During the development process, each model block was tuned by referring to the results of pre-test and parts acceptance tests. As a result, the entire performance model and the developed system were completely verified, through unit components and system integrated performance tests. Finally, we summarize the process and results applied to the design process of high-lift control system and present future work.

• The Korean Journal of Quaternary Research
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• v.22 no.1
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• pp.1-12
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• 2008

We investigated metal concentrations and oceanic environment changes that have occurred over the past several years by studying the hard coral Porites lutea, which inhabits tropical and subtropical areas. Soft X-radiographs clearly showed distinctive annual bands within 71 mm coral sample, which reflect changes in the oceanic environment over this period. There were large fluctuations in the major and minor element concentrations. Considering the physicochemical partition coefficient, some elements accumulated in the aragonite matrix in a mechanical manner, while others were affected by environmental factors. The concentrations of some heavy metals varied over a wide range, implying local environmental effects. The variation of Sr/Ca and Mg/Ca in coral skeleton clearly showed large-scale fluctuation over the specific intervals, implying environmental changes during this period. The concentrations of heavy metals also show high fluctuations, and roughly accord with Mg/Ca variation. In addition, Cu and Zn seem to show cyclicity-like peaks, coincide with Mg/Ca variation over the specific intervals. Such variation might be related to local pollution and oceanographic changes. More detailed investigation is necessary, including the pretreatment of coral skeleton sediment.

• Tuberculosis and Respiratory Diseases
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• v.50 no.1
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• pp.42-51
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• 2001

Background : Recently, cardiopulmonary exercise testing (CPX) has become a popular diagnostic method for differentiating the main cause of exertional dyspnea or exercise limitation. We evaluated the difference in the CPX results according to interpretative algorithms and the methals of exercise in Korea. Method : Sixty-six patients with chronic lung disease and 48 adults with dyspneic symptoms, but with no abnormalities in a spirometry performed symptom limited CPX, were included in this study. The results were interpreted using both Wasserman's(WA) and Eschenbacher's algorithm (EA), and a comparison between both algorithms was made. Thirty-three healthy medical students performed the CPX with a cycle ergometer and treadmill. The results were interpreted with EA and the concurrence in interpretations was evaluated accord ing to the methods of exercise. Results : 1. In patients with chronic lung disease, the overall concordance rate between the two algorithms was 63.6%. The concordance rates waw 69.8% in patients with obstructive, 25.0% in those with restrictive, and 66.7% in those with mixed pulmonary insufficiency. In patients with dyspneic symptoms but normal findings in resting spirometry, the concordance rate was 60.4%. 2. In healthy medical students, in results inter preted with EA, the concordance rate between the cycle ergometer and treadmill exercise was 25.0%. Conclusion : Both interpretative algorithms and methods of exercise may affect the CPX results. In using CPX as a diagnostic test for the causes of dyspnea in the Korean population. the interpretative algorithms and method of exercise need to be standardized, and a predictive $VO_2$max equation needs to be established.

• Progress in Medical Physics
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• v.20 no.3
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• pp.139-144
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• 2009

Recently, the mathematical analysis of stent simulation has been improved, with the help of development of various tool which measure mechanical property and location of stent in artery. The most crucial part of the stent modeling is how to design ideal stent and to evaluate the interaction between stent and artery. While there has been great deal of researches on the evaluation of the expansion, stress distribution, deformation of the stent in terms of the various parameters, few verification through computer simulation has been performed about deformation and stress distribution of the stent. In this study, we have produced the corresponding results between experimental test using Universal Testing Machine and computer simulation for the ideal model of stent. Also, we have analyzed and compared stress distribution of stent in the cases of that with membrane and that without membrane. The results of this study would provide minimum change of plan and good quality for ideal stent replacing damaged artery through the analysis using computer simulation in the early stage of stent design.

• Science of Emotion and Sensibility
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• v.21 no.1
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• pp.59-70
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• 2018

With the breakthrough of speech recognition technology, conversational agents have become pervasive through smartphones and smart speakers. The recognition accuracy of speech recognition technology has developed to the level of human beings, but it still shows limitations on understanding the underlying meaning or intention of words, or understanding long conversation. Accordingly, the users experience various errors when interacting with the conversational agents, which may negatively affect the user experience. In addition, in the case of smart speakers with a voice as the main interface, the lack of feedback on system and transparency was reported as the main issue when the users using. Therefore, there is a strong need for research on how users can better understand the capability of the conversational agents and mitigate negative emotions in error situations. In this study, we applied social strategies, "forewarning" and "apology", to conversational agent and investigated how these strategies affect users' perceptions of the agent in breakdown situations. For the study, we created a series of demo videos of a user interacting with a conversational agent. After watching the demo videos, the participants were asked to evaluate how they liked and trusted the agent through an online survey. A total of 104 respondents were analyzed and found to be contrary to our expectation based on the literature study. The result showed that forewarning gave a negative impression to the user, especially the reliability of the agent. Also, apology in a breakdown situation did not affect the users' perceptions. In the following in-depth interviews, participants explained that they perceived the smart speaker as a machine rather than a human-like object, and for this reason, the social strategies did not work. These results show that the social strategies should be applied according to the perceptions that user has toward agents.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.658-672
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• 2022

The unique teaching and learning difficulties of speed-related units in elementary school science are mainly due to the student's lack of mathematical thinking ability and procedural knowledge on speed measurement, and curriculums and textbooks must be constructed with these in mind. To identify the implications of composing a new science curriculum and relevant textbooks, this study reviewed the structure and contents of the speed-related units of three curriculums from the 2007 revised curriculum to the 2015 revised curriculum and the resulting textbooks and examined their relevance in light of the literature. Results showed that the current content carries the risk of making students calculate only the speed of an object through a mechanical algorithm by memorization rather than grasp the multifaceted relation between traveled distance, duration time, and speed. Findings also highlighted the need to reorganize the curriculum and textbooks to offer students the opportunity to learn the meaning of speed step-by-step by visualizing materials such as double number lines and dealing with simple numbers that are easy to calculate and understand intuitively. In addition, this paper discussed the urgency of improving inquiry performance such as process skills by observing and measuring an actual object's movement, displaying it as a graph, and interpreting it rather than conducting data interpretation through investigation. Lastly, although the current curriculum and textbooks emphasize the connection with daily life in their application aspects, they also deal with dynamics-related content somewhat differently from kinematics, which is the main learning content of the unit. Hence, it is necessary to reorganize the contents focusing on cases related to speed so that students can grasp the concept of speed and use it in their everyday lives. With regard to the new curriculum and textbooks, this study proposes that students be provided the opportunity to systematically and deeply study core topics rather than exclude content that is difficult to learn and challenging to teach so that students realize the value of science and enjoy learning it.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.442-448
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• 1999

We introduce the systematization design method using similarity theory which is profitable in the c compatability and standardization of the developed products and the reduction of construction time and price to d develop and design a machine equipment. Systematization design method is to select the standard model for d designing and developing from the large machinery to the super precision one and then to induce the c characteristic of machines step by step in advance in case of miniaturizing and making largelongleftarrowscale. With this m method, we extract the peculiar characteristics through the close analysis on the physical and ttx:hnical part a and predict the characteristic experiment for the magnitude we desire by an머ogical mathematical analysis. At l last, we will get the design sample the users demand with the verification of the data on optimum design p previously. In this paper, we could predict the characteristic of the product the users rC'Quire in advance with the d design method applying similarity theor${\gamma}$ and suggested the design method which could meet the various r requirements the users want. Also, it is shown that the standardization design by the similarity theory is a available as comparing the characteristic values expc'Cted through the experiment of the actual actuator with t the theoretical character data of similarity theoη after selecting the linear actuator as a model.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.1
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• pp.4011-4020
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• 1976

본논문은 북해도대학심사학위논문으로 총면수 143면인 영문으로 되어 있고 도 48, 표 7, 문묵 66부도, 부표 20면이있음. Plow는 옛부터 발달한 농구이기 때문에 많은 연구가 행하여졌지만 복잡한 물리성을 가준 토양을 대상으로 하는 기계이기 때문에 미해결의 문제도 적지않다. 이견인저항에 대하여 토양의 종류 및 조건을 변경하면서 실제의 포장에서 조직적으로 행한 실험은 극히 적고, 하물며 우리나라의 쟁기에 관한 연구는 거의없다. 본논문은 쟁기의 특징을 구명하고, 그의 개량, 발달에 기여하기 위한 기기자료를 획득코저 실시한 것이다. 1. 쟁기와 플라우의 구조 및 그의 차이 특징을 명백히하고 이체에 걸리는 각종의 저항의 내용 또는 그 비율등에 대하여 과거의 연구성과를 소개하였다. 2. 발달사 ; 플라우는 B.C. 2000년경에 녹각, 목지의 인력용의 경운용구에서 발달하고, 동양이도 기원은 대체로 같고 발달과정이 다를 뿐이다. 쟁기는 양자강연안에 기원을 가진 지나이가 신라와 백제에 도입되여 차차 발달하고, 지역적인 특징을 가지게 되었다. 3. 본장은 쟁기의 견인력에 관한 이론적해석을하고, 쟁기의 진행에 의해 층상으로 전단되는 전단저항을 구하고 쟁기의 표면 및 지측판과 토양과의 마찰력, 그리고 토양의 이동의 관성력을 쟁기의 견인저항에 관련되는 주요한 "힘"으로 생각하고 진행방면, 수직방면의 힘의 성분의 평형을 고려하여 식 10. 12를 유도 하였다. 4. 본장에서는 실험계획, 방법 공시기, 공시포장등을 기록하고, 축력용의 쟁기와 플라우를 사용하여 전지 4종 답 2종의 포장에서 실험하는데 견인력계와 자동경심측정기를 사용하였다. 5. 실험결과 및 고찰; 경심과 견인저항 Dp와의 관계는 식 10. 12와 갈이 표시되고, 실제의 제치를 대입하여 이론식을 유도하였으니 직선에 가까운 관계가 있고, 실험결과는 조금 곡선에 가까워졌다. 그리고, 토양의 물리성이 견인력Dp에의 영향을 세밀히 검토하였다. 쟁기의 견인비저항에 있어서도 식 12에서 {{{{K=AT+ { B} over {T } +C}}}}로 표시할수 있기 때문에 최소치를 표시하는 경심이 존재하고 이값은 쟁기나 플라우폭의{{{{ { 1} over {2 } }}}} 즉 10m정도이고 쟁기는 비저항이 0.llkg/$\textrm{cm}^2$에서 0.39kg/$\textrm{cm}^2$이였다. 그러나 이 비저항도 토양의 물리성이 많은 영향을 미치고 있다. 6. 요약 및 결론 ; 이상의 장에서 검토 고찰한 결과만을 기재하고 플라우는 쟁기에 비해 견인저항 및 비저항이 논에서나 밭에서 대로 나타난 것이 특이하다. 이상의 내용을 지면관계로 3회에 거쳐 요약 발표합니다.