• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.150-154
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• 2008

In this research, stress components and principal stresses of O-ring under internal pressure and under uniform squeeze rate were obtained from the stress freezing method of photoelastic experiment and photoelastic experimental Hybrid method for 3-dimensional problems. The obtaining processes of those were introduced. It was certified that the processes of those are effective for the 3-dimensional stress analysis of structures. Stress freezing method, the obtaining processes of those and photoelastic experimental hybrid method were effectively applied to the stress analysis of O-ring made from rubber that under uniform deformation and internal pressure. Stress components and principal stress of Oring under uniform squeeze rate and under internal pressure were analyzed.

• 천문학회지
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• 제40권3호
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• pp.61-65
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• 2007

The 2-1 and 5-4 transitions of SiO have been observed toward the Sgr B2 region, including the Principal Cloud(the GMC containing Sgr B2(M)) and its surroundings. The morphology and velocity structure of the SiO emission show a close resemblance with the HNCO Ring feature, identified by Minh & Irvine(2006), of about 10 pc in diameter, which may be expanding and colliding with the Principal Cloud. Three SiO clumps have been found around the Ring, with total column densities $N_{SiO}{\sim}1{\times}10^{14}cm^{-2}$ at the peak positions of these clumps. The fractional SiO abundance relative to $H_2$ has been estimated to be ${\sim}(0.5-1){\times}10^{-9}$, which is about two orders of magnitude larger than the quiet dense cloud values. Our SiO observational result supports the existence of an expanding ring, which may be triggering active star formations in the Principal Cloud.

• The Journal of Advanced Prosthodontics
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• 제7권4호
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• pp.303-311
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• 2015

PURPOSE. The aim of this study was to compare the changes in retentive force of stud attachments for implant overdentures by in vitro 2-year-wear simulation. MATERIALS AND METHODS. Three commercially available attachment systems were investigated: Kerator blue, O-ring red, and EZ lock. Two implant fixtures were embedded in parallel in each custom base mounting. Five pairs of each attachment system were tested. A universal testing machine was used to measure the retentive force during 2500 insertion and removal cycles. Surface changes on the components were evaluated by scanning electron microscopy (SEM). A Kruskal-Wallis test, followed by Pairwise comparison, was used to compare the retentive force between the groups, and to determine groups that were significantly different (${\alpha}$<.05). RESULTS. A comparison of the initial retentive force revealed the highest value for Kerator, followed by the O-ring and EZ lock attachments. However, no significant difference was detected between Kerator and O-ring (P>.05). After 2500 insertion and removal cycles, the highest retention loss was recorded for O-ring, and no significant difference between Kerator and EZ lock (P>.05). Also, Kerator showed the highest retentive force, followed by EZ lock and O-ring, after 2500 cycles (P<.05). Based on SEM analysis, the polymeric components in O-ring and Kerator were observed to exhibit surface wear and deformation. CONCLUSION. After 2500 insertion and removal cycles, all attachments exhibited significant loss in retention. Mechanism of retention loss can only be partially explained by surface changes.

• 한국가스학회지
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• 제18권4호
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• pp.51-55
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• 2014

본 연구에서는 한곳에서 접촉하는 오링과 여러 곳에서 접촉하는 멀티접촉패킹에 대한 밀봉특성을 유한요소법으로 해석하였다. FEM 해석결과에 의하면, LP가스압력 1.8MPa을 공급하였을 때 기존의 오링에서는 밀봉성에 관련된 2.5MPa의 수직접촉 최대응력을 발생하였다. 반면에 새롭게 고안된 멀티접촉패킹에서는 3.01MPa이 발생하여 20.4%나 높아진 밀봉성이 향상되었음을 알 수 있다. 또한, 밀봉내구 안전성에 밀접한 관련이 있는 압출현상은 기존 오링의 경우 1.62MPa의 가스압력에서 발생되었지만, 멀티접촉패킹에서는 1.8MPa 정도로 가스내압을 올려도 압출현상이 발생되지 않는 것은 오랫동안 밀봉작용을 한다는 것을 의미한다. 따라서 밀봉성과 내구안전성을 높게 요구할 때는 한곳에서 접촉하는 기존의 오링보다는 여러 곳에서 접촉하는 멀티접촉패킹을 사용하는 것이 유리함을 알 수 있다.

• 대한의용생체공학회:의공학회지
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• 제16권4호
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• pp.555-561
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• 1995

본 논문에서는 객관적이고 신뢰성있는 체질 식별을 위한 수단으로 기존의 O-링 테스트법의 단점을 보완한 O-링 경근력 계측시스템을 설계하여 임상에 적용하였다. 의사나 체질 식별 시술자의 손으로 행하던 O-Ring 측정을 공압 펌프와 액츄에이터를 이용하여 마이크로 컴퓨터로 제어함으로써 압력을 받은 실린더와 피스톤을 확장하게하여 고리모양으로 만든 피측정자의 손가락을 확장시키도록 설계하였다. 기존의 재래식 측정법이 단순히 측정자가 느끼는 주관적인 감각과 경험으로 피측정자의 경근력을 판단하므로 객관성이 결여되고 미세한 경근력의 변화는 판정이 불가능하였으나 O-링 경근력 계측시스템을 사용한 측정법은 미세한 경근력의 변화를 측정함은 물론 손가락의 확장거리 및 측정 시간까지 계측함으로써 경근력 변화를 판단하는 파라메터가 다양하고 신뢰성을 유지하게 하였다. 임상 실험 결과 O-링 경근력 계측시스템이 기존의 체질 진단법의 단점을 보완하고 보다 객관성있는 체질 진단의 가능성을 증가시키는 것으로 확인되었다. 차후 O-링 경근력 계측 시스템을 PC와 인터페이스시켜 측정된 임상 자료를 데이타베이스화 함으로써 많은 임상 자료를 기반으로 컴퓨터에서 전문가 시스템을 구축하여 체질 진단에 대한 보다 객관적이고 신뢰성이 높은 자동 진단 시스템으로 발전시키면 한의학적인 질변진단 분야에 기여할 수 있을것이다.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.89-94
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• 2007

The new pinane derivative containing unique multifused ring system was synthesized. The crystal, molecular and electronic structure of the title compound has been determined. Both pinane ring systems have the same conformation. The five-membered oxazolidine ring exists in twisted chair conformation. The structure is expanded through O-H…O hydrogen bond to semiinfinite hydrogen-bonded chain. The bond lengths and angles in the optimised structure are similar to the experimental ones. The CH3 and CH2 groups (except this of oxazolidine ring) are negatively charged whereas the CH groups are positively charged. The largest negative potential is on the oxygen atoms. The C-N natural bond orbitals are polarised towards the nitrogen atom (ca. 61% at N) whereas the C-O bond orbitals are polarised towards the oxygen atom (ca. 67% at O). It is consistent with the charges on the nitrogen and oxygen atom of oxazolidine ring and the direction of the dipole moment vector (3.08 Debye).

• Journal of the Korean Wood Science and Technology
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• 제45권5호
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• pp.661-670
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• 2017

지리산 아고산대 주요 침엽수(주목, 잣나무, 구상나무)와 신갈나무를 이용하여 50년간의 산소동위원소연대기(1966~2015)를 작성하였다. 산소동위원소연대기 작성은 크로스데이팅(cross-dating) 결과가 우수한 4본을 각 수종에서 선발하여 실시하였다. 동일 수종 내 임목 간 산소동위원소연대기의 상관분석 결과 모두 유의성(p < 0.001) 높은 상관이 있는 것으로 확인되었으며, EPS도 0.85 이상이었다. 동일 수종 내 임목 간 상관분석뿐만 아니라 수종간 상관분석에서도 유의성(p < 0.001) 높은 상관관계가 확인되었다. 기후요소(강수량, 기온)와 산소동위원소와의 관계를 조사하기 위한 반응함수 분석에서 주목은 당년 5월 강수량과 유의성 있는 부의 상관을 보였으며, 구상나무는 4월 강수량과 유의성 있는 부의 상관을 보였다. 향후 주목과 구상나무에 대한 장기간의 산소동위원소연대기가 작성된다면 과거 측정하지 못한 장기간의 4월과 5월 강수량 복원이 가능할 것이다.

• 사상체질의학회지
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• 제7권1호
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• pp.69-101
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• 1995

Using Bi-Digital O-Ring Test which was developed by Ohmura Toshiaki, constitution classification by the vegetables' was measured by various muscle power measurement meters and the results are as follow : 1. Pinch guage (Model : pc5030HPG, Japan) is the guage to measure finger power between the thumb and second finger, Grip Strength Dynamometer (Model : T.K.K. 5101, Japan) is to measure the hand power (hand dynamometer), Back Strength dynamometer (Model : T.K.K. 5102, Japan)is to measue back muscle strength, Vertical Jump Meter (Model : T.K.K. 5106, Japan) is to measure the height of jump. The above guages were used and its result found that the radish, potato, carrot and cucumber can influence to the muscle strength was not true. 2. When the physical constitution is distinguished vy the O-Ring Test method, Taeyangin's rate appeared as average 21% although it was insistedthat there will be only 0.03-0.1%. This means that the influence power of vegetable doest not appear according to the physical constitution but it appears accidently according to the examinee's emotion about the material such as vegetable etc. as favor or unfavor. 3. It was found that the result of O-Ring Test is the same at any time and at any place was not true. there is no reemergence character. 4. The import of O-Ring Test method to the physical discriminatio disregarded that the mental facor influences absolutely to the physical heath in the ideological physical constitution medicla science. 5. 'O-Ring Test method is a objective judgement method'. is wrong judgement. As you see on the above result, Bi-Digital O-Ring Test set the changeable voluntary muscle as the standard of the judgement, that was first mistake logically, second in spite of leass influence of mental influence by the examiner and examinee than the vegetable discrimination influence, the test disregarded the influence. Thire, only grasp of some material on hand can influence to the voluntary was a wrong theory disregarding the physiology. Finally the misunderstaning his subjective view as an objective view in spite of examiner and examinee's strong influence. Therefore such kind of physical descrimination method must be sublated.

• Korean Journal of Mathematics
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• 제27권1호
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• pp.141-150
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• 2019

In this article we investigate the structure of rings in which lower nilradicals coincide with upper nilradicals. Such rings shall be said to be quasi-2-primal. It is shown first that the $K{\ddot{o}}the^{\prime}s$ conjecture holds for quasi-2-primal rings. So the results in this article may provide interesting and useful information to the study of nilradicals in various situations. In the procedure we study the structure of quasi-2-primal rings, and observe various kinds of quasi-2-primal rings which do roles in ring theory.

• Korean Journal of Mathematics
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• 제28권3호
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• pp.483-488
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• 2020

In this paper, a new characterization concept is introduced for rings with identity, called the identical characteristic. Some general results are obtained for various ring classes and illustrated by several examples.