Osteochondral Lesion of the Talus: Prognostic Factors Affecting the Clinical Outcome After Arthroscopic Marrow Stimulation Technique

The treatment of symptomatic osteochondral lesions of the talus (OLT) has difficulties and limitations caused by the poor regeneration of articular cartilage and the limited access to the ankle joint. It is important that the surgeon understand the causes of failure as well as the factors influencing the results of arthroscopic treatment of OLTs. The presence of such a risk factor may encourage surgeons to find new treatment strategies as well as counsel patients differently.ope

다종 서비스를 제공하는 삼세대 무선 시스템에서의 호수락 제어

학위논문(박사) - 한국과학기술원 : 산업및시스템공학과, 2010.2, [ x, 82 p. ]Nowadays, mobile communication networks have evolved into 3G systems which accommodate various data communications as well as voice communications. 3G mobile communication networks aim at effective provision of packet data service such as internet or multimedia service, and these services request mobile network capacity more and more. Unlike internet which is a packet switching network, a general mobile communication network is a circuit switching network, and it requires efficient Call Admission Control (CAC) in order to manage limited radio resource efficiently. Since the circuit switching networks were developed, much engineering work has been done on the topics of efficient CAC; nevertheless, previous works are probably not directly applicable to a 3G system, because it has many different features from before 3G systems. Therefore, we will study previous CAC methods, and then, on the basis of them we will propose novel CAC schemes suitable for 3G systems. In addition, we will consider CAC at both rural and urban cell environment in Wideband Code Division Multiple Access (WCDMA) system for more practical study. In Chapter 2, efficient CAC at the rural cell environment is considered. First of all, radio resource reservation methods which have been considered in previous CAC schemes are studied and classified into several representatives. Then we examine them in the order of development, and improve them into suitable methods for 3G systems. In addition, we propose novel CAC schemes for the purpose of better performance in 3G systems. Computer simulations are performed to evaluate the performance of proposed schemes compared with previous schemes. Secondly in Chapter 3, the urban cell environment is considered. Since urban cells generally have more customers than rural cells, call admission requests are also more frequent in urban cells. For these reasons, it is easily expected that the larger data transmission capacity of a base station will be required i...한국과학기술원 : 산업및시스템공학과

Reoperation for persistent or recurrent hemifacial spasm after microvascular decompression

OBJECTIVE: The objective of this study was to investigate the outcome of reoperation for persistent or recurrent hemifacial spasm (HFS) after microvascular decompression (MVD). METHODS: Repeat MVD was performed on 13 patients with an HFS between June 1994 and May 2004. Patients who had compressing offending vessels identified on postoperative (prerevision) three-dimensional short-range magnetic resonance angiography were selected for repeat MVD. RESULTS: Six patients were found to have no improvement in HFS with the first MVD. All of these patients exhibited excellent improvement after the second MVD. In one patient who had mild improvement with the first MVD, but with more than 50% of remaining spasm, complete abolition of spasm occurred immediately after the second MVD. Six patients showed initial relief and subsequent aggravation of HFS after the first MVD. Of these patients, four had excellent results with the second MVD, one had a good result, and one had a fair outcome. Adverse effects after the second MVD were found in two patients (one patient with permanent mild facial weakness and one patient with hearing impairment). There was no serious morbidity associated with the second MVD. CONCLUSION: Our data suggest that repeat MVD of the facial nerve may be sufficient to resolve symptoms in selected patients with persistent or recurrent HFS. Additionally, three-dimensional short-range magnetic resonance angiography may help to identify the offending vessels and to select the patients with persistent or recurrent HFS.ope