Hyo Young Kim

Development of a Novel Spherical Actuator With Two Degrees of Freedom

This paper describes the design and implementation of a novel spherical actuator that can generate two tilt-motion degrees of freedom. Voice coil motors were adopted as actuators in a spherical actuator to utilize their simple driving principle and constant torque coefficient characteristic. The sensing and guiding mechanism was built inside the proposed spherical actuator and enabled compactness and ease of connection to other application systems. The actuator was designed using a design optimization framework to obtain high torque. A prototype actuator was manufactured with optimally designed parameters, and its performance was evaluated.

Reply: The effect of platelet-rich plasma on flap survival in random extension of an axial pattern flap in rabbits.

69e The Effect of Platelet-Rich Plasma on Flap Survival in Random Extension of an Axial Pattern Flap in Rabbits Sir: I read with great interest the article by Kim et al. This article was published in July of 2013 and concerns the effect of platelet-rich plasma on flap survival.1 The authors nicely showed that platelet-rich plasma can improve flap survival area. I would like to complete the discussion of Kim and colleagues by introducing a major complementary route through which platelet-rich plasma could reduce flap necrosis. There is a growing body of evidence that a significant portion of flap necrosis is triggered by a sequence of events associated with reperfusion of ischemic tissues, termed “reperfusion injury.”2 The major explanation for reperfusion phenomena is up-regulation of surface adhesion molecules on the vascular endothelium with subsequent adherence and accumulation of polymorphonuclear leukocytes within the vessel lumen. Adherence of polymorphonuclear leukocytes is mediated predominantly by beta-2 integrins (CD11/CD18) on their surface through activation of the NF-kappaB/RANKL pathway.3 Osteoprotegerin, which is a decoy receptor of RANKL, can block the NF-kappaB/RANKL pathway.4 Platelet-rich plasma, which is also called platelet gel, effectively stimulates osteoprotegerin production, leading to significant block of the beta-2 integrin/ NFkappaB/RANKL pathway, which subsequently leads to decreased polymorphonuclear leukocyte aggregation and reperfusion injury.5 Therefore, this important mechanism should be borne in mind as the major complementary mechanism for platelet-rich plasma– reduced flap necrosis. DOI: 10.1097/01.prs.0000436527.70708.07

Treatment preferences of advanced ovarian cancer patients for adding bevacizumab to first-line therapy

BACKGROUNDnThe GOG-218 and ICON-7 studies recently showed that adding bevacizumab to first-line therapy for patients with advanced ovarian cancer increased progression-free survival. However, the high cost and long treatment duration prevents the incorporation of bevacizumab in practice. The aim of this study was to explore and quantify patients preferences for adding bevacizumab to first-line therapy.nnnMETHODSnA discrete choice experiment (DCE) and trade-off question were designed and distributed to 102 ovarian cancer patients. Participants were asked to choose between two hypothetical first-line therapies that differed in terms of effectiveness, safety, and the financial burden. A trade-off technique varying the cost of bevacizumab was used to quantify a willingness-to-pay threshold for selecting bevacizumab.nnnRESULTSnAll attributes of the DCE had a statistically significant impact on respondents preferences and the financial burden was the most important attribute. The results of the trade-off question showed that more than half of patients would prefer to add bevacizumab to standard chemotherapy when the cost of the drug was reduced to 17% (1/6) of the baseline cost.nnnCONCLUSIONnPatients preferences for bevacizumab in the adjuvant treatment of ovarian cancer depend primarily on drug costs. Our results suggest that the current cost of bevacizumab is sufficiently high that the majority of ovarian cancer patients are not willing to pay to accept a small increase in progression-free survival.

Design and Control of a 6-DOF Active Vibration Isolation System Using a Halbach Magnet Array

Active vibration isolation systems (AVIS) reduce the vibrations transmitted to ultraprecision mechanical systems by providing managed stiffness and damping. Many types of AVIS are used in various fields. In nanoprecision measuring instrument fields, such as atomic force microscopy and scanning probe microscopy, the requirement for isolation of ground vibrations has always been of great interest to researchers. Bench-top-type six-degree-of-freedom (6-DOF) AVIS have been widely used in ultraprecision measuring applications. This paper describes the design, modeling, optimization, and validation of a new 6-DOF AVIS. The unique feature of the proposed system is its voice coil motor actuator that uses a Halbach magnet array to produce a high force constant. The results obtained using the proposed AVIS show that it can serve as a bench-top device for precision measuring machines.

Treatment Preferences for Routine Lymphadenectomy Versus No Lymphadenectomy in Early-Stage Endometrial Cancer

AbstractBackgroundnDebate on the value of lymphadenectomy continues in endometrial cancer. The aim of this study was to investigate patient and clinician preferences for routine lymphadenectomy versus no lymphadenectomy in the surgical management of endometrial cancer.MethodsA discrete choice experiment and trade-off question were designed and distributed to 103 endometrial cancer patients and 90 gynecologic oncologists. Participant preferences were quantified with regression analysis using scenarios based on three attributes: 5-year progression-free survival and the rates of acute and chronic complication. A trade-off technique varying the risk of recurrence for no lymphadenectomy was used to quantify any additional risk of recurrence that these participants would accept to receive no lymphadenectomy instead of routine lymphadenectomy.ResultsOn the basis of discrete choice experiment, the recurrence rate and lymphedema risk had a statistically significant impact on respondents’ preference. The trade-off question showed that the median additional accepted risk of having no lymphadenectomy was 2.8% for gynecologic oncologists (0.5–14%) and 3.0% for patients (0.5–10%), but this difference was not significant (pxa0=xa00.620). Patients who were younger or had a higher education level or no history of delivery or shorter duration since diagnosis were prepared to accept higher additional risks of having no lymphadenectomy.ConclusionsOur results show that the majority of endometrial cancer patients and clinicians will accept a small amount of recurrence risk to reduce the incidence of lymphedema. Regarding preference heterogeneity among patients, our results show that it is important for surgeons to take a patient-tailored approach when discussing surgical management.

The Impact of Non-Financial Incentives on Judgmental Forecasting Performance

We analyze the effects of non-financial incentives that provide relative performance feedback on judgmental forecasting performance. Using a controlled laboratory experiment, we find that the provision of such non-financial incentives improves judgmental forecasting accuracy, especially when subjects are consistently informed that their ranks are the lowest in the group. This is consistent with loss aversion, i.e., people’s tendency to avoid losses is stronger than to acquire gains. Competitors who are behind see their performance as a loss and work harder than those who are ahead to avoid the loss. On the contrary, subjects who are consistently told that they are ranked the first, perform worse as the leading participants tend to slack off. We also find that non-financial incentives when combined with financial reward, impede forecasting performance.

Analysis of a 3-DOF Rotationally Symmetric Hinge

Flexure hinges have been widely used as mechanisms for high precision positioning stages that have a micrometer or nanometer resolution. This paper describes the analysis of a 3-DOF rotationally symmetric hinge for the vertical mask aligner stage. The vertical mask aligner stage was designed to overcome the bending of masks by gravity. In order to align the mask and the wafer, the vertical mask aligner stage has one linear motion and yaw rotating motions (Z, Θx, Θy). The new vertical mask aligner stage will try to use rotationally symmetric hinges. These rotationally symmetric hinges would act as guide mechanisms. However, the exact 6-DOF stiffness analysis of the rotationally symmetric hinge did not use these hinges as guide mechanisms. Therefore, this paper focuses on the stiffness analysis of the rotationally symmetric hinges.