• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.307-310
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• 1998

Finite element analysis was investigated on the stress distribution at the 2-D model of piezoelectric ceramic actuators. The y direction maximum stress decreased with a(internal electrode gap) size until 0.4 mm and is not much difference with c(external electrode thickness) size. The stress distribution with internal layers is almost same, and the stress distribution of load condition is higher than that of no load condition. The y direction maximum stress increased exponentially with the number of layer and saturated at 260 layers. In the case of defective actuator, the stress distribution is smaller than that of normal actuator.

• 한국정밀공학회지
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• 제8권2호
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• pp.89-105
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• 1991

A method to apply the approximation formulae[1] for tooth fillet and root stresses of a thin-rimmed rack to the calculation of stress state of thin-rimmed external and internal spur gears is introduced. The stress values by the method proposed in this paper have shown good agreement with those by the REM analysis and also by the stress measurement of strain survey investigation. By this method, reliable stress state at tooth fillet and root areas in the thin-rimmed external and internal spur gears can be easily calculated, and a practical design method for the bending strength of such thin-rimmed gears is established.

• 한국자기학회지
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• 제5권5호
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• pp.533-537
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• 1995

The stress in Permalloy thin films fabricated by rf magnetron sputtering on the Si (100) substrates has been investigated with various deposition parameters such as the film thickness, argon pressure, and rf power. The internal stress changes from compressive to tensile with higher input power and argon pressure. The cause of stress variations with these deposition parameters is discussed in terms of thermal and/or intrinsic stress changes. Low coercive force is obtained from Permalloy thin films at a condition of low compressive stress.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.39-43
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• 2022

In this paper, a study was conducted on encapsulation technology for high mechanical stability of flexible displays. First, unlike conventional encapsulation barrier that exclude cracks as much as possible for low water vapor transmission rate (WVTR), mechanical properties were improved by using a defect suppression mechanism introduced with crack arresters. The zero-stress encapsulation barrier optimizes the residual stress of the thin film based to improve the internal mechanical stability. The zero-stress encapsulation barrier was applied to the organic light emitting diodes (OLEDs) to confirm its characteristics and lifetime. Due to improved internal mechanical stability, it has a longer lifetime more than 35% compared to conventional encapsulation technologies. As the zero-stress encapsulation barrier proposed in this study does not require additional deposition process, it is not difficult to apply it. Based on various advantages, it is expected to play an important role in flexible displays.

• 대한치과보철학회지
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• 제41권5호
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• pp.617-625
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• 2003

Statement of problem : There are many studies focused on the effect of shape of futures on stress distribution in the mandibular bone. However, there are no studies focused on the effect of the abutment types on stress distribution in mandibular bone. Purpose : The purpose of this study is to investigate the effect of three different abutment types on the stress distributions in the mandibular bone due to various loads by performing finite element analysis. Material and method : Three different implant systems produced by Warantec (Seoul, Korea), were modeled to study the effect of abutment types on the stress distribution in the mandibular bone. The three implant systems are classified into oneplant (Oneplant, OP-TH-S11.5). internal implant (Inplant, IO-S11.5) and external implant (Hexplant, EH-S11.5). All abutments were made of titanium grade ELI. and all fixtures were made of titanium grade IV. The mandibular bone used in this study is constituted of compact and spongeous bone assumed to be homogeneous, isotropic and linearly elastic. A comparative study of stress distributions in the mandibular bone with three different types of abutment was conducted. Results : It was found that the types of abutments have significant influence on the stress distribution in the mandibular bone. It was due to difference in the load transfer mechanism and the size of contact area between abutment and fixture. Also the maximum effective stress in the mandibular bone was increased with the increase of inclination angle of load. Conclusion : It was concluded that the maximum effective stress in the bone by the internal implant was the lowest among the maximum effective stresses by other two types.

• 대한핵의학회지
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• 제25권2호
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• pp.165-176
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• 1991

The purpose of this study was to assess the ability of quantitative Tl-201 tomography to identify and localize coronary artery disease (CAD). The study population consisted of 41 patients (31 males, 10 females; mean age $55{\pm}7$ yr) including 14 with prior myocardial infarction who underwent both exercise Tl-201 myocardium SPECT and coronary angiography for the evaluation of chest pain. From the short axis and vertical long axis tomograms, stress extent polar maps were generated by Cedars-Sinai Medical Center program, and the % stress defect extent (SDE) was quantified for each coronary artery territory. For the purpose of this study, the coronary circulation was divided into 6 arterial segments, and the "myocardial ischemic score" (MIS) was calculated from the coronary angiogram. Sensitivity for the detection of CAD ($\geq50%$ coronary stenosis by angiography) by angiography) by stress extent polar map was 95% in single vessel disease, and 100% in double and triple vessel deseases. Overall sensitivity was 97%. Sensitivity and specificity for the detection of individual diseased vessels were, respectively, 87% and 90% for the left anterior descending artery (LAD), 36% and 93% for the left circumflex artery (LCX), and 71% and 70% for the right coronary artery (RCA). Concordance for the detection of individual diseased vessels between the coronary angiography and stress polar map was fair for the LAD (kappa=0.70), and RCA (kappa=0.41) lesions, whereas it was poor for the LCX lesions (kappa : 0.32). There were siginificant correlations between the MIS and SDE in LAD (rs=0.56, p=0.0027), and RCA territory (rs=0.60, p=0.0094). No significant correlation was found in LCX territory. When total vascular territories were combined, there was a significant correlation between the MIS and SDE (rs=0.42, p=0.0116). In conclusion, the quantitative analysis of Tl-201 tomograms appears to be accurate for determining the presence and location of CAD.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.908-913
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• 2000

In the process of integrity evaluation for nuclear power plant components, a series of fracture mechanics evaluation on surface cracks in reactor pressure vessel(RPV) must be conducted. These fracture mechanics evaluations are based on stress intensity factor, K. However, under pressurized thermal shock(PTS) conditions, the combination of thermal and mechanical stress by steep temperature gradient and internal pressure causes considerably high tensile stress at the inside of RPV wall. Besides, the internal pressure during the normal operation produces high tensile stress at the RPV wall. As a result cracks on inner surface of RPVs may experience elastic-plastic behavior which can be explained with J-integral. In such a case, however, J-integral may possibly lose its validity due to constraint effect. In this paper, in order to verify the suitability of J-integral, two dimensional finite element analyses were applied for various surface crack. Total of 18 crack geometries were analyzed, and Q stresses were obtained by comparing resulting HRR stress distribution with corresponding actual stress distributions. In conclusion, HRR stress fields were found to overestimate the actual crack-tin stress field due to constraint effect.

• 대한토목학회논문집
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• 제32권4A호
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• pp.227-235
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• 2012

최근 기둥의 구속효과에 대한 연구가 많이 연구되어지고 있다. 주로 철근 콘크리트 기둥과 CFT(Concrete Filled Tube)기둥과 같이 중실 기둥에 대한 연구로 한정되어 있는 반면 중공 기둥에 대한 구속효과 연구가 매우 미비한 실정이다. 중공 기둥의 외부 구속력에 대한 연구가 주로 연구되고 있고 내부 구속력을 외부 구속력과 동일하게 가정하고 구속 콘크리트의 구속효과를 평가하고 있다. 본 연구에서는 중공 CFT 기둥에 내부 튜브를 삽입하여 구속 콘크리트 3축 구속 상태로 놓이게 하여 연성 및 강도를 상승 시킨 내부 구속 중공 CFT 기둥(Internally Confined Hollow CFT, ICH CFT)의 최적 구속메커니즘을 도출하기 위한 연구를 하였다. 내부튜브 두께, 중공비, 기둥의 직경, 콘크리트와 외부튜브의 휨강성비를 매개변수로 삼아 범용 FEM 프로그램으로 비선형 해석 연구를 수행하여 최적 내부 구속력 도출을 통하여 수정 파괴 조건식을 제안하였다. 수정 파괴 조건식은 최적 내부 튜브의 두께를 산정하여 기둥이 경제성을 확보하도록 하였다.

• 대한한의학회지
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• 제20권1호
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• pp.172-184
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• 1999

This study was aimed to evaluate the anti-stress effect of Kungchihwadamjeun on the body weight. organs weight, S- GOT. S-GPT. lipid peroxidase in organs and contents of cathecholamine in brain of rats stressed by immobilization. The main results obtained were summarized as follow 1. The body weights increased in the group treated with Kungchihwadamjeun of rats stressed by immobilization compared with in the group treated with non Kungchihwadamjeun. 2. The weight of the spleen. kidney. pancreas, thymus and heart increased in the group treated with Kungchihwadamjeun of rats stressed by immobilization compared with in the group treated with non Kungchihwadamjeun. 3. The contents of serum GOT GPT decreased in the group treated with Kungchihwadamjeun of rats stressed by immobilization compared with in the group treated with non Kungchihwadamjeun 4. The lipid peroxidase in liver decreased in the group treated with Kungchihwadamjeun of rats stressed by immobilization compared with in the group treated with non Kungchihwadamjeun. 5. The contents of norepinephrine and serotonine in brain decreased in the group treated with Kungchihwadamjeun of rats stressed by immobilization compared with in the group treated with non Kungchihwadamjeun, but epinephrine and dopamine in brain increased. According to the above results, this experiments concluded that Kungchihwadamjeun had significant effects in reducing stress.

• Tuberculosis and Respiratory Diseases
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• 제84권2호
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• pp.159-166
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• 2021

Background: E-cigarettes are steadily gaining popularity in Korea. However, the characteristics of e-cigarette smokers, especially nicotine dependence and stress susceptibility, have not been evaluated in comparison to those of nonsmokers or combustible cigarette smokers in Korea. Methods: In this study, 28,059 participants from the Korea National Health and Nutrition Examination Survey (2013-2017) were classified into the following three groups: non-smokers, smokers (current smokers and ex-smokers of combustible cigarettes only), and e-smokers (current smokers and ex-smokers of e-cigarettes regardless of combustible cigarette use). Results: Among the participants, 16,980 (60.5%), 9,247 (33.0%), and 1,832 (6.4%) subjects were non-smokers, smokers, and e-smokers, respectively. E-smokers were younger, more educated, and had a higher household income than non-smokers or smokers. The number of e-smokers who smoked within 5 minutes of waking up (31.5% vs. 19.8%, p<0.001) and who planned to quit smoking within 6 months (39.1% vs. 35.7%, p<0.05) was greater than that of smokers. E-smokers perceived stress as "very much" (7.0% vs. 4.4%, p<0.001) and "a lot" (29.1% vs. 20.5%, p<0.001) compared to non-smokers. Suicidal ideation (6.5% vs. 4.7%, p<0.001), plans (2.4% vs. 1.3%, p<0.001), and attempts (1.1% vs. 0.5%, p<0.001) were higher in e-smokers than in non-smokers. Depressive episodes in 1 year (14.2% vs. 11.4%, p<0.05) and suicidal plans (2.4% vs. 1.8%, p<0.05) were more frequent among e-smokers than among smokers. Conclusion: E-smokers were younger, more educated, and had a higher income, but they were more dependent on nicotine and susceptible to stress than non-smokers and smokers. Smoking cessation counseling should be tailored according to the characteristics of e-smokers.