• 대한토목학회논문집
• /
• 제29권6C호
• /
• pp.251-258
• /
• 2009

본 연구에서는 모래다짐말뚝 (SCP)로 개량된 연약점토지반상의 성토시공에 있어서 최적설계조건에 대해 현행 설계법과 손실평가함수 및 1차 근사 2계 모멘트법 (AFOSM)에 기초한 신뢰성 설계법으로 비교 검토하였다. 결과를 요약하면 다음과 같다. 1) 안전율(Fs)와 파괴확률($P_F$)는 심한 비선형 관계를 나타냈고, Fs가 1.2로 증가함에 따라 $P_F$는 약 1%까지 급격한 감소를 나타낸 후, 안전율의 증가와 더불어 $P_F$는 점진적으로 감소하였다. 현행 설계법상의 기준 안전율 1.2는 둘의 관계에 있어서 일종의 임계값이며, 이들의 관계가 적절히 고려되어 정립되었다고 판단된다. 2) 최소기대총비용을 나타내는 안전율은 1.15부근으로 현행설계기준 1.2에 다소 못미치는 값으로 나타났고, 파괴확률은 1% 정도로 다소 컸다. 3) 응력분담비 n과 모래의 내부마찰각 ${\phi}$의 민감도가 연약층의 초기비배수강도 관련 변수들의 민감도보다 더 크게 나타났다. 이것은 n과 ${\phi}$의 변동 특성이 보다 해석결과에 큰 영향을 준다는 것과 이들 변동 특성은 SCP 개량지반상의 성토안정해석에 반드시 고려되어야 함을 의미한다. 4) 설계기준안전율 1.2 이상(파괴확률 0.1-0.3% 이하)에서 New Failure Point는 평균치에서 표준편차의 1~2배 가량 떨어져 있는 값을 나타냈다.

• 한국생산제조학회지
• /
• 제19권5호
• /
• pp.609-615
• /
• 2010

Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.

• International Journal of Quality Innovation
• /
• 제2권2호
• /
• pp.24-33
• /
• 2001

As we know, the quality of processes is technically depicted by variation, a product or process with the best quality must naturally require the variation as less as possible. The variation is usually reduced with many ways, say, by adjusting parameters settings under robust design with many turns expensive experiments. So ones are trying to reach the robustness by detecting cheap and simple methods. In this paper, a both practical and simple technique for quality improvement, namely reducing the variation, by data classification is studied. First, all possible system factors are included, which may dominate the variation law. And then we make use of the past observations and their classification as well as boxplot charts to find out the internal rule between the variation and the system factor. Next, adjust the location of the system factor according to the rule so that the variation could, to some extent, be lessened. Finally, two typical quality improvement cases based on data classification are presented.

• 한국생활과학회지
• /
• 제15권2호
• /
• pp.251-259
• /
• 2006

The purpose of this study is to identify main effect of gender and expenditure, and interaction effect of gender by expenditure on satisfaction with foodservices of western restaurants. Accordingly, this study surveyed questionnaires concerning 20 measures of foodservice as well as major subject descriptors. The result of this study was as follows: KMO and Bartlett's test statistics showed that the data well fitted a factor analysis. Results of the factor analysis, average variance extracted estimates, and shared variance showed that the convergent and discriminant validities of 5 factors were supported, and Cronbach's alpha also showed that the internal consistencies of 5 factors were supported. But there was an interaction effect between independent variables and covariate on service quality factor. This study, therefore, used food decor factor, facility factor, food quality factor, and food value factor as dependent variables in two way 3$\times$2 design factorial ANCOVA. It was found that there were no main effects of gender and expenditure on those four factors. It was however revealed that there was an interaction effect of gender by expenditure on food decor factor.

• 한국초등과학교육학회지:초등과학교육
• /
• 제35권1호
• /
• pp.123-135
• /
• 2016

Interest is one of the important factors in science education. The purpose of this study was to investigate factors affecting the follow-up interest of elementary school students on topics of 'Small Organisms' World'. The follow-up interests of the students on the topic were grouped into three categories; the developed-expanded-deepened (EDD), the simply expanded and maintained (SEM), and the stoped or decreased (SD) types. Each types had specific distinguishing features. Through the examination of students' responses and the in-depth interviews, the factors affecting on the follow-up interests of the students were analyzed. The factors were classified into two types of the external factor and the internal one. While the external factors were mainly related to the instructional materials used in science class and teaching methods, the internal factors were related to the desire for knowing, prior knowledge, students' experience and attitude toward the topics of science. In relation to the types of the follow-up interests, these factors were affected by different causes. The EDD type was most affected by internal factors, such as desire for knowing and prior knowledge. The SEM type was shown to be most affected by external factors, such as instructional materials. The SD type was mainly influenced by external factors, such as teaching methods. From the analysis of internal factors, it was revealed that the attitude and the prior knowledge about the topic are related with the follow-up interests. There was a positive relationship between the levels of science attitude and science knowledge. The students who had EDD type had a higher level of attitude and knowledge. However, there were some students who had higher level of scientific knowledge with SD type. The results of in-depth interviews showed that they were influenced by negative perceptions about science and stress on their grades. In conclusion, each follow-up interest type were caused by the external factors contained in the processes of the science class and the internal ones associated with the individual features and were influenced by the science class. So, the teacher should help the students be able to have the EDD type of follow-up interest which is persisted even after the completion of the science curriculum. For this, when the teachers design science curriculum and plan lesson, they should consider both internal and external factors significantly influencing the students' follow-up interests.

• The Journal of Advanced Prosthodontics
• /
• 제5권3호
• /
• pp.312-318
• /
• 2013

PURPOSE. The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS. A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ${\alpha}$=.05. RESULTS. The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 ${\mu}m/m$ at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION. Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit.

• 대한가정학회지
• /
• 제43권10호
• /
• pp.1-23
• /
• 2005

This study proposes design factors for Korean style ecological apartment for application in Cheongju. Library and internal surveys were performed to summarize the concept of locality in housing and to determine the present condition of apartment estates which were introduced with design factors according to locality, traditionalism, or ecology, fold surveys were carried out at 10 apartment estates to investigate the present condition of management and residents's un. The interviewees were concierges and representative residents. The following design factors for Korean style ecological apartment to be applied in Cheongju were proposed; layout and building shape according to climate as natural environment, landscape factors according to cultural assets as human environment, adolescent spaces according to population as social environment, road plan according to 'Cheongju Garosu-Gil' civil environment.

• 디자인학연구
• /
• 제16권3호
• /
• pp.221-230
• /
• 2003

제품디자인에서 Fun이라는 주제를 표현하기 위해 많은 디자이너들이 심리학적 측면에서의 접근방법을 사용하고 있다. 그렇다면 심리학에서 이야기 하는 Fun발생 메커니즘은 제품디자인에 접목하기에 많은 보완이 필요하다고 본다. 현재 심리학에서는 Fun이라는 감성을 유발시키기 위한 메커니즘으로 어떤 상황을 직면하였을 때 심적 정체를 겪은 후, 어떠한 실마리에 의한 정체의 해소를 겪게 될 때 Fun을 느끼게 된다고 이야기 한다. 심리학적 측면에서 Fun을 발생시키는 메커니즘의 도출은 그 접근 방식 자체에서 인지적인 측면의 Fun만을 이야기 하는 경향이 있다. 이러한 성향은 조형을 가지고 있는 제품디자인을 이야기 할 경우, 제품에서 중요한 역할을 가지는 지각적인 측면의 재미를 충분히 설명하기에는 역부족인면이 있다. 본 연구에서는 심리학에서 다루어지는 인지적 재미요인 이외에 지각적인 측면의 Fun을 제품디자인에서 같이 논의하는 것이 좀더 타당한 접근방법이라는 가설을 세웠다. 이를 위해 지각적 측면의 Fun을 이해하기 위해 키치라는 문화현상 중에 키치제품의 유희성이라는 측면을 도입하기로 한다. 키치제품의 유머러스한 형태를 도출하는 방법을 이야기 하고 있으며 이러한 방법들이 지각적인 측면에서도 같이 적용될 수 있는 것이다. 이러한 가설을 통하여, 내면의 기능적 특성인 인지적 요소와 표면적 고유특성인 지각적인 요소가 모두 거론되어야 실질적인 방법으로 사용될 수 있으리라 생각된다.

• Steel and Composite Structures
• /
• 제25권2호
• /
• pp.209-216
• /
• 2017

In this paper, the analysis of the behavior of surface cracks in finite-thickness plates repaired with a Boron/Epoxy composite patch is investigated using three-dimensional finite element methods. The stress intensity factor at the crack-front was used as the fracture criteria. Using the Ansys Parametric Design Language (APDL), the stress intensities at the internal and external positions of repaired surface crack were compared. The effects of the mechanical and geometrical properties of the adhesive layer and the composite patch on the variation of the stress intensity factor at the crack-front were examined.

• 한국전산유체공학회지
• /
• 제19권4호
• /
• pp.14-19
• /
• 2014

This study conducts shape optimization of rib turbulator on the internal cooling passage that has triangular cross-section of high pressure turbine nozzle. During optimization, various types of rib turbulator including angled, V-shaped, A-shaped and angled rib with intersecting rib are considered. Each type of rib turbulator is parameterized with attack angle(s), rib height, spacing ratio and bending/intersecting location. For optimization, Design of Experiment (DOE) and Kriging surrogate model are used to utilize computational resource more efficiently and Genetic Algorithm (GA) is used to search the optimum points. As a result, Pareto front of each type of rib turbulator with friction factor that relates to pressure drop in cooling passage and spatially averaged Nusselt number that relates to heat transfer on the wall is drawn and optimum points on the Pareto front are suggested.