A 36-year-old man was admitted to our institute due to the diagnosis of esophageal submucosal tumor detected by a periodical upper gastrointestinal endoscopic examination without any complaint. Thoracoscopic enucleation of the lesion with the preoperative clinical diagnosis of esophageal leiomyoma was performed under general anesthesia in the prone position. After immunohistochemical examination, the pathological diagnosis was leiomyoma. There was no remarkable event during the postoperative hospital stay, and the patient was discharged on the 12th day after surgery. This case report suggests that the prone position might be superior to the left lateral decubitus position in thoracoscopic enucleation of esophageal leiomyoma.

Recently, there has been an increasing demand for miniaturization and multi-functionalization of electronic equipments due to the developments in information technology (IT). Thus, the miniaturization of printed wiring boards (PWBs) and fabrication of highly dense electrical circuit layers are needed to realize the miniaturization and densification of the semiconductor package PWBs. Micro-drilling technology has been attracing attention to machine the electronic micro-through holes with an ultra-high-speed spindle, more than 160 krpm. However, problems have emerged; the drill tool bends and suffers breakage in the drilling process and the heat damage around the drilled hole after a drilling process occurs due to the increase in the drilling aspect ratio between hole depth and diameter. In general, a step feed drilling method is considered an effective way to solve these problems. However, short stroke alternating motion in the spindle axis is needed to do the step drilling process and its motion causes various kinds of vibration. We constructed a machine tool with a novel counter balance mechanism in the spindle driving Z-axis and investigated a model to estimate a proper balance mass for the step drilling process. We compared the frequency response results from a proposed model with the experimental ones, and discussed a control on vibration due to the counter balance mechanism. The results demonstrate that a proposed vibration proof method was found to reduce the vibration in high-speed step-micro-drilling motion and to improve the drilled hole quality and the efficiency of micro-drilling process in the PWB manufacturing fields.

Recently, many researchers have been studying Brain Computer Interface (BCI) by which we can operate objects with analyzing Electroencephalogram (EEG) instead of hands. One of them, by using event related synchronization from EEG during motor imagery of each hand, discriminated right or left hand's movement [1]. However, these methods enable us to discriminate only a few classes. Furthermore,