Independent feature screening for ultrahigh-dimensional models with interactions

송윤관,Xuehu Zhu,Lu Lin 한국통계학회 2014 Journal of the Korean Statistical Society Vol.43 No.4

Feature selection is an important technique for ultrahigh-dimensional data analysis. Mostfeature selection methods such as SIS and its relevant versions heavily depend on thespecified model structures. Furthermore, feature interactions are usually not taken intoaccount in the existing literature. In this paper, we present a novel feature selectionmethod for the model with variable interactions, without the use of structure assumption. Thus, the new ranking criterion is flexible and can deal with the models that containinteractions. Moreover, the new screening procedures are not complex, consequently, theyare computationally efficient and the theoretical properties such as the ranking consistencyand sure screening properties can be easily obtained. Several real and simulation examplesare presented to illustrate the methodology.

수종 탄성의치상 이장재의 물리적 특성에 관한 실험적 연구

송윤관,박주미,송광엽,박찬운 全北大學校 齒醫學硏究所 1991 전북치대논문집 Vol.9 No.1

The purpose of the present study was to evaluate the effects of storage time and condition on the weight change, dimensional stability and softness of six commercially available soft lining materials. Ten specimens each 1.8㎜ in thickness of soft lining materials were bonded to poly(methylmethacrylate) made in the form of circular disk 50㎜ in diameter and 1.5㎜ in thickness using steel molds, then stored in simulated mouth condition(artificial saliva, pH 7.4, 37±1℃). The specimens were tested after 0, 1, 7, 14, 28, 42 and 56days. The data were analyzed by one way analysis of variance with Duncan's multiple range test. The results of this study were obtained as follows : 1. For permanent soft lining material Mollosil showed a significant decrease in weight after 42days, for provisional soft lining material Coe Comfort showed a significant increase in weight after 28days(p<0.05) between the aging times. 2. For permanent soft lining material Coe Soft showed a significant increase in dimensional change after 42days(p<0.05), but the other gorups showed no significant difference between the aging times(p>0.05). 3. For Molloplast-B material a significant difference in softness was not found between the aging times(p>0.05), Coe Super-Soft showed a significant decrease in softness after 7days, and Coe soft, Mollosil, Visco-gel and Coe Comfort showed a significant decrease in softness after 28days(p<0.05).

티타늄과 금합금의 레이저 용접부의 인장강도

송윤관,송광엽,하일수,Song, Yun-Gwan,Ha, Il-Soo,Song, Kwang-Yeob 대한치과보철학회 2000 대한치과보철학회지 Vol.38 No.2

Lasers have given dentistry a new rapid, economic, and accurate technique for metal joining. Although laser welding has been recommended as an accurate technique, there are some limitations with this technique. For example, the two joining surfaces must have a tight-fitting contact, which may be difficult to achieve in some situations. The tensile samples used for this study were made from a custom-made pure titanium and type III gold alloy plates. 27 of 33 specimens were sectioned perpendicular to their long axis with a carborundum disk and water coolant. Six specimens remained and served as the control group. A group of 6 specimens was posed as butt joints in custom parallel positioning device with a feeler gauge at each of three gaps : 0.00, 0.25. and 0.50mm. All specimens were then machined to produce a uniform cross-sectional dimension, none of the specimens was subjected to any subsequent form of heat treatment. Scanning electron microscopy was performed on representative tested specimens at fractured surfaces in both the parent metal and the weld. Vickers hardness was measured at the center of the welds with a micropenetrometer using a force of 300gm for 15 seconds. Measurement was made at approximately $200{\mu}m\;and\;500{\mu}m$ deep from each surface. One-way analysis of variance (ANOVA) and Scheffe's test was calculated to detect differences between groups. The purpose of this study is to compare the strength and properties of the joint achieved at various butt Joint gaps by the laser welding of type III gold alloy and pure titanium tensile specimens in an argon atmosphere. The results of this study were as follows : 1. When indexing and welding pure titanium, there was no decrease in ultimate tensile strength as compared with the unsectioned alloys for indexing gaps of 0.00 to 0.50mm, although with increasing gap size may come increased distortion (p>0.05). 2. When indexing and welding type III gold alloy, there were significant differences in ultimate tensile strength among groups with weld gaps of 0.00mm, 0.25 and 0.50mm, and the control group. Group with butt contact without weld gap demonstrated a significant higher ultimate tensile strength than groups with weld gaps of 0.25 and 0.50mm (p<0.05). 3. When indexing and welding the different metal combination of type III gold alloy and pure titanium, there were significant differences in ultimate tensile strength between groups with weld gaps of 0.00, 0.25, and 0.50mm. However, the mechanical properties of the welded joint would become too brittle to be acceptable clinically (p<0.05). 4. The presence of large pores in the laser welded joint appears to be the most important factor in controlling the tensile strength of the weld in both pure titanium and type III gold alloy.

차량기반 정전용량센서 응용에 대한 평가법 개발

송봉기(Bonggi Song),이석우(Seokwoo Lee),윤관식(Gwansik Yoon) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11

Processing and Properties of Poly (lactic acid) Composite Films Filled with Carbon Particles

조용범,송인성,김대근,윤관한,방대석,조동환 한국고분자학회 2009 한국고분자학회 학술대회 연구논문 초록집 Vol.2009 No.10

중합방법이 다른 의치상 레진의 적합도 평가

이상건,송윤관,송광엽 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.3

In addition to continuing the search for more accurate and dimensionally stable materials for denture bases, recently several processing methods for denture base resins which may reduce dimensional change during fabrication has been developed. The purpose of this study was to compare the dimensional accuracy of denture bases cured by four denture base processing methods, using the conventional heat-compression molding method, the continuous-pressure injection method, the microwave curing processing method, and the Sulfone system. A metal die simulating a maxillary edentulous arch and a polyvinylsiloxane impression(Reprosil, L. D. Caulk Co. U.S.A.) were used to construct 40 simulated master casts and denture bases with artificial teeth. Forty simulated denture bases 3 to 4㎜ thick were processed by four denture base processing methods following the manufacturer's instructions. The processed denture bases and casts sectioned through the posterior palatal region to allow measurement of its change by means of an travelling microscope. Observations were made on center of posterior palatal sectioned region. One-way ANOVA and paired samples t-tests were employed to compare the differences in distortion after deflasking and after finishing and polishing. The obtained results were as follows; 1. After deflasking, dimensional changes were diminished in order of conventional heat-compression molding, Sulfone system, continuous-pressure injection method, microwave processing method(p<0.05). 2. After finishing and polishing, dimensional changes were diminished in order of conventional heat-compression molding method, Sulfone system, microwave processing method, continuous-pressure injection method. The significant difference was found between conventional hear-compression method, continuous-pressure injection method(p<0.05). 3. The significant difference was found between after deflasking and after polishing in all methods, except continuous-pressure injection method(p<0.05).