• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.3
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• pp.217-224
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• 2024

This paper proposes an efficient dimension reduction method (DRM) that considers the nonlinearity of the performance functions in reliability-based design optimization (RBDO). The dimension reduction method evaluates the reliability more accurately than the first-order reliability method (FORM) using integration quadrature points and weights. However, its efficiency is hindered as the number of quadrature points increases owing to the need for an additional evaluation of the performance function. In this study, we assessed the nonlinearity of the performance function in RBDO and proposed criteria for determining the number of quadrature points based on the degree of nonlinearity. This approach suggests adjusting the number of quadrature points during each iteration of the RBDO process while maintaining the accuracy of theDRM while improving the computational efficiency. The nonlinearity of the performance function was evaluated using the angle between the vectors used in the maximum probable target point (MPTP) search. Numerical tests were conducted to determine the appropriate number of quadrature points according to the degree of nonlinearity. Through a 2D numerical example, it is confirmed that the proposed method improves the efficiency while maintaining the accuracy of the dimension reduction method or Monte Carlo Simulation (MCS).

• Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.96-102
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• 2014

In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahedralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.

• Communications of the Korean Mathematical Society
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• v.9 no.4
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• pp.905-915
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• 1994

Let $M_g$ be the moduli space of isomorphism classes of genus g smooth curves. It is a quasi-projective variety of dimension 3g - 3, when $g > 2$. It is known that a complete subvariety of $M_g$ has dimension $< g-1 [D]$. In general it is not known whether this bound is rigid. For example, it is not known whether $M_4$ has a complete surface in it. But one knows that there is a complete curve through any given finite points [H]. Recently, an explicit example of a complete curve in moduli space is given in [G-H]. In [G-H] they constructed a complete curve of $M_3$ as an intersection of five hypersurfaces of the Satake compactification of $M_3$. One way to get a complete curve of $M_3$ is to find a complete one dimensional family $p : X \to B$ of plane quartics which gives a nontrivial morphism from the base space B to the moduli space $M_3$. This is because every non-hyperelliptic smooth curve of genus three can be realized as a nonsingular plane quartic and vice versa. This paper has come out from the effort to find such a complete family of plane quartics. Since nonsingular quartics form an affine space some fibers of p must be singular ones. In this paper, due to the semistable reduction theorem [M], we search singular plane quartics which can occur as singular fibers of the family above. We first list all distinct plane quartics in terms of singularities.

• Journal of the Korean housing association
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• v.22 no.5
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• pp.91-100
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• 2011

The purpose of this study was to investigate the social exclusion of 'Da-Ka-Gu' rental housing and permanent rental apartments and to provide basic source of their socio-demographic characteristics and actual conditions of social exclusion. Self-administered questionnaires and interviews were carried out with 212 dwellers in 'Da-Ka-Gu' rental housing and permanent rental apartments in the city of Gwangju from July to October of 2010. The main findings are: 1. The social exclusion of physical deficiency dimension composed of income and employment has been found to be the most serious level, compared to all the other dimensions. 2. The social exclusion from health has been found to be the highest level in the dimension of the approach to social rights. The next highest level has been found to be the social exclusions from residential areas and education and service areas. 3. The level of social exclusions from the areas of family relations and social relations, which are in the dimension of social participation, has been found to be next highest to the level of physical deficiency dimension. 4. The level of exclusion from cultural and normative integration has not been found to be of significant difference between the two types of residence in this study. This study of the actual conditions of social exclusion among residents living in 'Da-Ka-Gu' rental housing and permanent rental apartments suggests the necessity and some practical implications for policy measures of social integration for the residents of lowincome housing.

• Journal of Oral Medicine and Pain
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• v.11 no.1
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• pp.67-78
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• 1986

This study was attempted to identify the emotional characteristics of temporomandibular disorder patients. The author applied one of the self-report modes of psychological measurement, Symptom Chechlist-90-Revision. The subjects were 219 TM disorder patients who visited the Department of Oral Diagnosis and Oral Medicine, Seoul National University Hospital during the period from December 1985 to September 1986. All the patients were divided into subgroup according sex, age, duration of symptoms, presence or absence of T-scores of each symptom dimension and global index. The obtained result were as follows : 1. Mean value of T-scores of each symptom dimension and global of the overall patients was within normal range. The two higher mean values of T-scores among 9 symptom dimensions were those of SOM and ANX. 2. Mean values of T-scores of females were higher than those of males in the O-C, DEP, ANX, HOS, PSY dimensions and all global indices, and there was a significant difference in the distribution of T-scores of the SOM dimension between males and female(P<0.05). 3. There was no significant difference between the subgroup under 30 years and the subgroup 30 years or older. 4. The subgroup with symptoms for 6 months or longer showed the higher mean values of T-scorers in the SOM, O-C, I-S, DEP, ANX, PHOB, PAR, PSY dimensions and all global indices compared with the subgroup with symptoms for shorter than 6 months. 5. The subgroup with pain showed the higher mean values of T-scores in all the symptom dimensions except the PAR in comparison with the subgroup with other complaints than pain, and there was a significant difference in the distribution of T-scores of the PST index between the pain subgroup and the non-pain subgroup(P<0.05). There was a significant difference in the distribution of T-scores of the PHOB dimension between the high-school graduates subgroup and the college graduates subgroup(P<0.05).

• Journal of Korean Academy of Nursing Administration
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• v.5 no.2
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• pp.369-388
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• 1999

This study is a descriptive research to establish a positioning strategy of nursing service image, making a perception map on each hospital's nursing service image and ranking construct factors of nursing service image. The results in this study were as follows; 1. The rank of construct factors of nursing service image which were thought important by subjects was the first 'Kindness', the second 'Reliability', the third 'Professional Knowledge', the fourth 'Responsibility', and the fifth 'Advanced Nursing Skill'. 2. The perception map for nursing service image on each hospital showed a hierarchial structure and positioned the first B hospital, the second C hospital, the third D hospital, the fourth A hospital, and the fifth E hospital. The perception map for construct factors of nursing service image and hospitals showed the first dimension : 'Reliability', the second dimension : Kindness', the third dimension : 'Mission', 'Accuracy', 'Neat Appearance', and 'Ethical Aspect', and the fourth dimension : 'Client Advocate', 'Humanistic Consideration', 'Professional Knowledge', 'Responsibility', and 'Advanced Nursing Skill'. 3. The findings of subject's characteristics which affected degree of likeness on each hospital nursing service image to make a marketing strategy were as follows : In A hospital D hospital, and E hospital, the subject group whose hospital dates were under 1 week, education level was upper graduate university, and age was between 40's and 50's, were appeared to have low nursing service image on following construct factors : 'Kindness', 'Reliability', 'Responsibility', 'Mission', 'Neat Appearance', and 'Humanistic Consideration'. In B hospital and C hospital the subject group whose hospital dates were under 1 week or over 5 weeks, sex was woman, and age was 20' s or 40's, having a admission experience on subject hospitals, were appeared to have low nursing service image on following construct factors : 'Professional Knowledge', 'Advanced Nursing Skill', 'Ethical Aspect', and 'Humanistic Consideration'. As the based on above results, nursing managers can use positioning method to develope a marketing strategy for nursing service image.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.213-213
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• 2016

현재 반도체 산업에서는 디바이스의 고 집적화, 고 수율을 목적으로 패턴의 미세화 및 웨이퍼의 대면적화와 같은 이슈가 크게 부각되고 있다. 다중 패터닝(multiple patterning) 기술을 통하여 고 집적 패턴을 구현이 가능해졌으며, 이와 같은 상황에서 각 패턴의 임계치수(critical dimension) 변화는 패턴의 위치 및 품질에 큰 영향을 끼치기 때문에 포토마스크의 임계치수 균일도(critical dimension uniformity, CDU)가 제작 공정에서 주요 파라미터로 인식되고 있다. 반도체 광 리소그래피 공정에서 크롬(Cr) 박막은 사용되는 포토 마스크의 재료로 널리 사용되고 있으며, 이러한 포토마스크는 fused silica, chrome, PR의 박막 층으로 이루어져 있다. 포토마스크의 패턴은 플라즈마 식각 장비를 이용하여 형성하게 되므로, 식각 공정의 플라즈마 균일도를 계측하고 관리 하는 것은 공정 결과물 관리에 필수적이며 전체 반도체 공정 수율에도 큰 영향을 미친다. 흔히, 포토마스크 임계치수는 플라즈마 공정에서의 라디칼 농도 및 식각 선택비에 의해 크게 영향을 받는 것으로 알려져 왔다. 본 연구에서는 Cr 포토마스크 에칭 공정에서의 Cl2/O2 공정 플라즈마에 대해 O2 가스 주입량에 따른 식각 선택비(etch selectivity) 변화를 계측하여 선택비 제어를 통한 Cr 포토마스크 임계치수 균일도 향상을 실험적으로 입증하였다. 연구에서 사용한 플라즈마 계측 방법인 발광분광법(OES)과 optical actinometry의 적합성을 확인하기 위해서 Cl2 가스 주입량에 따른 actinometer 기체(Ar)에 대한 atomic Cl 농도비를 계측하였고, actinometry 이론에 근거하여 linear regression error 1.9%을 보였다. 다음으로, O2 가스 주입비에 따른 Cr 및 PR의 식각률(etch rate)을 계측함으로써 식각 선택비(etch selectivity)의 변화율이 적은 O2 가스 농도 범위(8-14%)를 확인하였고, 이 구간에서 임계치수 균일도가 가장 좋을 것으로 예상할 수 있었다. (그림 1) 또한, spatially resolvable optical emission spectrometer(SROES)를 사용하여 플라즈마 챔버 내부의 O atom 및 Cl radical의 공간 농도 분포를 확인하였다. 포토마스크의 임계치수 균일도(CDU)는 챔버 내부의 식각 선택비의 변화율에 강하게 영향을 받을 것으로 예상하였고, 이를 입증하기 위해 각각 다른 O2 농도 환경에서 포토마스크 임계치수 값을 확인하였다. (표1) O2 11%에서 측정된 임계치수 균일도는 1.3nm, 그 외의 O2 가스 주입량에 대해서는 임계치수 균일도 ~1.7nm의 범위를 보이며, 이는 25% 임계치수 균일도 향상을 의미함을 보인다.

• Korean Journal of Child Studies
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• v.11 no.1
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• pp.58-71
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• 1990

The purpose of the study was to investigate the mother-child interactions in terms of maternal child- rearing behavior, maternal self-esteem, and their school-age children's self-esteem. The subjects were, all living in the Seoul area. A pre-test was conducted twice on 98 subjects. Each time the values of Chronbach's ${\alpha}$ were obtained on maternal behavior, maternal self-esteem and children's self-esteem. Data analysis was by ANOVA, Pearson's product-moment correlation. multiple regression analysis. Chronbach's ${\alpha}$, and factor analysis. Children's self-esteem was positively related (1) to family background factors:educational level, employment status of mothers, social economic status, and number of siblings (2) to maternal self-esteem and (3) to maternal child-rearing behavior in the dimensions of affection, acceptance, and encouragement of independency. Children's self-esteem was negatively related to maternal child-rearing behavior in the dimensions of hostility, rejection and encouragement of dependency. The relative importance of independent variables on children's self-esteem was found to be in the following order:mother's educational level. social economic status, and number of siblings (${\beta}=0.5935$, p< .001), maternal child-rearing behavior in the affection-hostility dimension (${\beta}=0.0849$, p< .001), and in the acceptance-rejection dimension(${\beta}=0.0365$, p< .05). The regression model showed that 25 percent of the children's self-esteem could be accounted for by family background factors. and maternal child-rearing behavior in the affection-hostility dimension and the acceptance-rejection dimension ($R^2=0.25$).

• Journal of Korean Neurosurgical Society
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• v.59 no.6
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• pp.604-609
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• 2016

Objective : The aim of this study was to compare the clinical and radiological outcomes associated with the use of hydroxyapatite (HA) spacer and allogeneic bone (AB) spacer in laminoplasty. Methods : From January 2006 to July 2014, 79 patients with cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament underwent cervical laminoplasty. The radiologic parameters were obtained from plain radiography and three-dimensional computed tomography. All images were taken before and after surgery. Cervical lordosis, spinal canal dimension, fusion between lamina and spacer, and resorption of spacer were checked. Clinical outcomes were assessed using visual analog scale and Japanese Orthopedic Association. Results : Double-door laminoplasty was performed on 280 levels : 182 in the HA group and 98 in the AB group. The mean follow-up was 23.1 months (range : 4-69 months). Similar fusion rates were found in these groups (p=0.3). The resorption rate between lamina and spacer was lower in the HA group (p<0.001). During the immediate postoperative period, the canal dimension of both groups increased compared with the results in the preoperative period. However, the canal dimension of the AB group decreased over time compared with that of the HA group (p<0.001). Conclusion : Double-door laminoplasty improved the clinical outcomes of both groups. However, the spinal canal dimension in the AB group showed a greater degree of reduction than in the HA group at the final postoperative follow-up. Therefore, we suggest that surgeons consider the use of larger-sized AB spacers in double-door laminoplasties.

• Journal of the Korean Society for information Management
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• v.30 no.2
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• pp.7-33
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• 2013

The purpose of this study is to analyze the user satisfaction, royalty and compliant of a children's library Website. To achieve the aim of this study a modified Kim and Park's model of the user satisfaction index which consists of information quality, service quality, and system quality dimension is adopted. A total of 130 valid responses to the questionnaire were analysed using SPSS 18. It is found that the higher the user satisfaction gives the higher the royalty and the lower the compliant. For the contents quality dimension, the items of Usability, Accuracy, Easy of understand, Reliability and Up-to-date; for the service quality dimension, the items of Interface design, Reliability, Responsiveness, and Empathy; for the system quality dimension, the items of Response time, Interactive, Easy to access, and Easy to use show a significant relationships to the users' satisfaction.