• International Journal of Ocean System Engineering
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• 제1권1호
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• pp.9-15
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• 2011

This study examined the relationship between the scarf angle and stress distribution, and estimated the strength recovery via a finite element analysis. The following conclusions were drawn from this study. Resin will fracture due to a tensile load with a high scarf angle, which is similar to the patch repair method. An applied stress can be loaded to a repaired laminate if the scarf angle is $5^{\circ}$. The Von-Mises stress increases with decreasing scarf angle, with the exception of a scarf angle of $30^{\circ}$, where the scarf angle can indicate the rates of shear and normal stresses. Strength recovery can be better if the scarf angle is decreased to a lower angle. However, scarf machining requires more time, a high skill level and considerable expense. Therefore, a scarf angle of $5^{\circ}$ is the most effective for a repair. These results may provide a guide for engineers wishing to formulate a standard for repair. The scarf angle needs to be carefully managed for a more efficient composite repair.

• 한국전기전자재료학회논문지
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• 제19권1호
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• pp.46-51
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• 2006

This paper reports on the effects of silicone oils, used as processing agents, on the recovery of hydrophobicity of silicone rubber. The recovery of hydrophobicity was evaluated by the measuring the contact angle, the surface electrical resistance and SEM. Here, we formed artificial contamination on the surface of samples, which scratched by sand papers and alumina powders. There was small recovery of hydrophobicity on the surface of SIR-A that silicone oil was not added. In both oil-added samples, SIR-B and SIR-C, recovery of hydrophobicity was achieved greatly. The surface of SIR-C showed that a lot of silicone oil was observed due to migration of oil, relatively in comparison with SIR-B. The tendency of recovery of hydrophobicity expressed by contact angle was in a good agreement with electrical property as determined by surface resistivity.

• 한국전기전자재료학회논문지
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• 제15권2호
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• pp.133-140
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• 2002

This paper aims to investigate the effect of silicone oils as processing agent affecting the loss and recovery of hydrophobicity. The recovery of hydrophobicity was evaluated by the measurement of the surface electrical resistivity and the contact angle on the SIR surface. Two kinds of silicone oils (1 and 2) having different molecular weight were selected under a consideration of hydrophobicity and processability. SIR specimens were exposed to corona discharges in air and the specimens were analyzed with contact angle and surface resistance measurements. It was observed that the contact angle and the surface resistivity of SIR increase gradually with testing time. The fast recovery of hydrophobicity of SIR, expressed by the increment of contact angle and surface resistivity, was showed in SIR2 containing silicone oil 2.

• Journal of Yeungnam Medical Science
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• 제40권3호
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• pp.252-258
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• 2023

Background: The purpose of this study was to investigate whether postoperative cystography findings can predict early and longterm recovery from incontinence after radical prostatectomy (RP), compared with the other cystography parameters. Methods: I retrospectively reviewed 118 patients who underwent robot-assisted RP (RARP) for localized prostate cancer at single institution between January 2016 and April 2021. One hundred and seven patients were included in the study. Postoperative cystography was routinely performed 7 days after surgery. The bladder neck to pubic symphysis ratio, vesicourethral angle, and bladder neck anteroposterior length (BNAP) ratio (the bladder neck-posterior margin distances divided by the anteroposterior lengths) were evaluated. Continence was defined as cessation of pad use. The association between these variables and urinary incontinence was also analyzed. Results: The urinary incontinence recovery rates 1, 3, 6, and 12 months after RARP were 43.92%, 66.35%, 87.85%, and 97.19%, respectively. Multivariate logistic regression analysis demonstrated that a lower BNAP ratio and wider vesicourethral angle were significantly associated with continence restoration at 1, 3, and 6 months after surgery. In addition, in terms of days of pad usage, lower BNAP ratio, wider vesicourethral angle, and bladder neck preservation were significantly associated with recovery from urinary incontinence within 12 months as assessed by Cox proportional hazard analysis. Conclusion: This study demonstrated that vesicourethral angle and BNAP ratio were independent predictors of early recovery from post-prostatectomy incontinence. I suggest that both the sagittal and coronal views of postoperative cystography help anticipate early continence restoration after RARP.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1702-1714
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• 1998

Removal of spilled oil over the sea and the river has become one of the urgent problems in these days. Removing oil using mechanical devices was recommended because chemical dispersion could cause the secondary contamination in the environment. In the present study a series of experiments were carried out to study the effect of operating conditions, especially, the angle between the belt and the fluid surface on the rate of recovery for the spilled oil using a belt skimmer. Three different types of operation, namely, upward pickup, downward pickup and up-and-downward pickup situations have been investigated for various contact angles, belt speeds and oil thicknesses to find the effects on the recovery rate. The highest rate of oil recovery was found in the case of a contact angle of $45^{\circ}$ and downward pickup. Furthermore, an optimal belt speed was found to reach the saturated recovery rate for a given oil thickness.

• 한국의류학회지
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• 제11권3호
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• pp.57-65
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• 1987

The purpose of this study was to investigate the optimum treatment [condition for the Durable press finish of viscose rayon fabrics. Three types of commercial N-methylol crosslinking agents were applied to the fabric utilizing the pad-dry-cure technique. Changes in physical properties were evaluated for the various resin and catalyst concentrations. For DMU, the effect of different catalysts, $MgCl_2$ and $NH_4Cl$, were also compared. DMU treated fabrics showed in crease recovery angle, tensile strength and tearing strength but drastic decrease in abrasion resistance. DMDHEU and MDMDHEU treated fabrics were similar in most physical properties. However, DMDHEU treated fabrics were better in crease recovery angle and stiffness, and MDMDHEU treated fabrics were better in tensile strength, tearing strength and abrasion resistance. For a given resin system, crease recovery angle, tensile strength and stiffness increased with a increase in resin concentration. Tearing strength showed very little change, while abrasion resistance was decreased significantly as the crease recovery angle was increased. For the treatment of DMU, $MgCl_2$ catalyst was much better than $NH_4Cl$ in all physical properties. When $NH_4Cl$ catalyst was used, strength reduction and discoloration were observed. As the catalyst concentration increased, crease recovery angle, stiffness were increased. Tensile strength and tearing strength were increcased than control but at high catalyst concentration, the strength were decreased and abrasion resistance was significantly lowered. DMDHEU and MDMDHEU were more sensitive to catalyst concentrations than DMU.

• 한국해양환경ㆍ에너지학회지
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• 제6권4호
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• pp.52-66
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• 2003

본 연구에서는 물리, 기계적인 누유 제거방법으로서 부착식의 일종인 드럼식 유회수기를 사용하여 회수조건의 변화에 따른 유회수율을 실험적으로 구하였다. 일반적으로 기계적인 유회수방법에서 문제시되는 것은 고점도 유체에서 유회수가 어렵고, 얇은 유막층에서 회수유중물의 함량이 증가하며, 유회수율이 크게 감소되는 점이다 본 연구에서는 드럼식 유회수기를 이용하여 드럼의 잠긴 깊이에 따른 접촉각, 이송속도, 유막두께 등의 유회수 조건이 유회수율에 미치는 영향을 디젤유를 사용하여 구하고 이를 분석하여 효과적인 유회수 조건을 구하였다. 실험결과 드럼식 유회수기에서 유회수율은 부착유량과 부착유량의 이탈손실에 의하여 영향을 받으며, 부착유량은 잠긴 깊이에 의한 접촉각에 영향을 받는다. 드럼식 유회수기에서의 유회수율은 드럼의 지름에 대한 잠긴 깊이의 비 h/d=0.15(접촉각 45°)에서 가장 효가적인 유회수율을 보이며, 얇은 유막두께에서도 비교적 효과적인 유회수율과 회수효율을 보였다. 또한 이송속도는 최대양정유량을 보이는 임계이송속도를 갖으며, 임계이송속도는 유막두께의 증가에 따라 증가한다.

• 치위생과학회지
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• 제6권4호
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• pp.231-235
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• 2006

본 연구는 부가중합형실리콘인상재의 정밀 인상채득에 영향을 미치는 요인, 압축변형률, 탄성회복률, 점주도와 젖음성을 평가하기 위하여 현재 시판되고 있는 4종류의 인상재 Examixfine(GC), Aquasilultra(Dentsply), Extrude(Kerr), Perfect-F(Handae)를 이용하여 실험하였다. 실험 데이터는 SPSSWIN 12.0을 사용하여 분석하였고, 결과는 다음과 같다. 1. 압축변형률은 Extrude가 4.86%로 가장 낮게 나타났고, Examixfine이 6.78%로 가장 크게 나타났다. Examixfine과 Perfect-F 사이에는 유의한 값의 차이가 없었으나, 다른 인상재 그룹에서는 유의성이 있었다. (p < 0.001). 2. Extrude의 탄성회복률이 99.83%로 가장 크게 나타났고, Perfect-F가 96.54%로 가장 낮게 나타났다. Examixfine과 Aquasilultra 간에는 유의성이 없었으나, 다른 인상재그룹간에는 유의한 차이가 있었다(p < 0.001). 3. 점주도의 측정결과에서 Examixfine이 점주도 값이 45.12mm로 가장 높았고, Perfect-F의 경우 40.28 mm로 가장 낮은 점주도 값을 나타내었다. Examixfine과 Aquasilultra, Extrude와 Perfect-F 간에는 유의한 차이가 나타나지 않았다(p > 0.001). 4. 젖음성에서는 Aquasilultra가 $47.85^{\circ}$로 가장 접촉각이 작게 나타나 친수성이 가장 우수하게 나타났고, Perfect-F는 접촉각이 $94.89^{\circ}$로 접촉각이 크게 나타나 소수성으로 나타났다. 인상재 종류별로도 각각 유의성이 존재하였다 (p < 0.001). 5. 접촉각은 압축변형률(p < 0.01), 탄성회복률(p < 0.01), 점주도(p < 0.05)와 상관관계가 있었고, 탄성회복률과 점주도 와는 음의 상관관계를 보였다. 압축변형률은 접촉각, 탄성회복률과 상관관계가 있었고(p < 0.01), 탄성회복률과 음의 상관관계를 나타냈다. 탄성회복률은 접촉각, 압축변형률과 음의 상관관계를 가지고 있었고(p < 0.01), 점주도도 접촉각과 음의 상관관계를 보였다(p < 0.05).

• 대한전기학회논문지
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• 제37권12호
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• pp.854-861
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• 1988

The current source inverter-fed induction motor(CSIM) drive is widely used in industry because of its four quadrant operation, fuseless protection, fuseless protection, and ruggedness. the CSIM drive system, however, has shortcomins such as slow response and dynamic stability to load torque disturbance and reference speed change. Such a disadvantages can be compensated considerably by means of introducing additional angle angle control loop. The angle control method is dependent upon the inverter type. In this paper, simultaneus recovery and commutation inverter(SRCI) which is developed recently is considered.

• Ocean Systems Engineering
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• 제10권1호
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• pp.1-23
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• 2020

Hydrodynamic Drag of Surface combatants pose significant challenges with regard to fuel efficiency and exhaust emissions. Stern flaps have been used widely as an energy saving device, particularly by the US Navy (Hemanth et al. 2018a, Hemanth Kumar and Vijayakumar 2018b). In the present investigation the effect of flap turning angle on drag reduction is numerically and experimentally studied for a high-speed displacement surface combatant fitted with a stern flap in the Froude number range of 0.17-0.48. Parametric investigations are undertaken for constant chord length & span and varying turning angles of 5° 10° & 15°. Experimental resistance values in towing tank tests were validated with CFD. Investigations revealed that pressure increased as the flow velocity decreased with an increase in flap turning angle which was due to the centrifugal action of the flow caused by the induced concave curvature under the flap. There was no significant change in stern wave height but there was a gradual increase in the stern wave steepness with flap angle. Effective length of the vessel increased by lengthening of transom hollow. In low Froude number regime, flow was not influenced by flap curvature effects and pressure recovery was marginal. In the intermediate and high Froude number regimes pressure recovery increased with the flap turning angle and flow velocity.