• The KIPS Transactions:PartC
• /
• v.8C no.1
• /
• pp.75-87
• /
• 2001

The Conditional Access System is the complete system for ensuring that broadcasting services are only accessible to those who are entitled to receive them. Four major parts to this system are scrambling, descrambling, authentication and encryption. For the proper operation, which means hard-to- break and uninterrupted service, secure key management and efficient delivery mechanism are very important design factors to this system. Performance analysis is another important factor to this system that is used in massive subscriber environment. In this thesis, one of the secure and efficient key management mechanisms is proposed. For the secrecy of this mechanism, hierarchical stacking of keys and key generation matrix are proposed. For the proof of efficient delivery of those keys, simulation results and performance analysis. which is based on queuing analysis, are presented. Lastly, optimal key generation and delivery period, maximal and minimal key deliver time, and communication capacity for data collection are presented for various subscriber volume.

• Korean Journal of Cleft Lip And Palate
• /
• v.10 no.2
• /
• pp.67-74
• /
• 2007

After Tennison introduced a triangular flap method which, for the first time, preserved the Cupid's bow, Randall gave this method a sound mathematical basis. This method is also called as an inferior triangular cheiloplasty which is characterized by making a small triangular flap from the lateral border of cleft destined to be fitted into an incision on the medial side of cleft. He postulated that the height obtained was equal to the sum of the median of the two triangles used in the cheiloplasty. Using this technique, a 22 month-old male patient with incomplete unilateral cleft lip was corrected primarily. The deviation of the columella and flattening of the nostril on the cleft side were minimal. The operation was done under general anesthesia and patient was healed uneventfully. We tried to improve the symmetry and esthetic feature of philtrum, nostril sill, alar-facial groove, preventing the notch formation on the nostril floor, and to reconstruct the muscle sling in the upper part of lip. The shape of Cupid's bow was restored, and the symmetry of columella was regained as a result. In summary, the inferior triangular cheiloplasty is effective to correct the primary unilateral cleft lip, results in the restoration of favorable anatomy and function.

• Journal of Chest Surgery
• /
• v.18 no.1
• /
• pp.46-53
• /
• 1985

A single aortic valve replacement using the lonescu-Shiley bovine pericardial xenograft valve was performed in 66 consecutive patients during the period from February, 1979 to June, 1984. They were 49 males and 17 females with ages ranging from 9 to 61 [mean, 31.113.1] years, and 9 of them were children younger than 15 years of age. Twenty-seven patients [40.9%] required the combined operative procedures to either other valvular lesions or congenital defects. There were 9 early deaths within 30 days of surgery [operative mortality rate, 13.6%] and 2 late deaths thereafter [late mortality rate, 3.0%; or 1.75%/patient-year]. The 57 early survivors were followed for a total duration of 114.2 patient-years [mean, 24.016.0 months]. Four patients experienced thromboembolic complication with no death [3.50%/patient-year]; one died from intracranial bleeding related to anticoagulation [0.88%/patient-year]; one recovered from prosthetic valve endocarditis [0.88%/patient-year]; and four developed aortic regurgitant murmur with none or minimal cardiac symptoms and they were classified into cases of tissue valve failure [3.50%/patient-year]. The actuarial survival rate was 82.34.7% at 6 years, and the actuarial probabilities of freedom from thromboembolism and valve failure were 93.33.9% and 89.15.8% at postoperative 6 years respectively Symptomatic improvement was excellent in most late survivors at the follow-up end with the mean of NYHA Classes of 1.040.19 while the one was 2.290.67 at the time of operation. Excluding the higher operative mortality rates, these clinical results are fully comparable with the ones of reports from the major institutions using the porcine aortic or the bovine pericardial tissue valves and warrants the continued use of the xenograft valve in the aortic position. The importance of more detailed preoperative evaluation of the myocardial function and the need of improved myocardial preservation during surgery for the improved early clinical results were discussed.

• Journal of Korean Neurosurgical Society
• /
• v.40 no.6
• /
• pp.406-411
• /
• 2006

Objective : The authors have developed a procedure, termed posterior microscopic lesionectomy, that creates a minimal laminotomy site according to the location of the shifted disc using the $METRx^{TM}$ system in the lumbar spine. This study compared the usefulness and surgical outcomes of this procedure with those of traditional standard lumbar discectomy. Methods : From June 2003 to June 2004, Twenty-two patients with one-level radiculopathy due to lumbar disc herniation underwent posterior microscopic lesionectomy with the assistance of an operating microscope and the $METRx^{TM}$ tubular retractor. Surgical results of the new procedure were compared to those of 39 patients who underwent traditional lumbar discectomy from April 2003 to September 2004. All patients were evaluated for pain score, clinical assessment according to the VAS, and Roland-Morris scores pre-operatively and at 1, 3, 6, and 12 months post-operatively. Results : Mean blood loss, operation time, and admission date showed significant improvements for microscopic lesionectomy compared to traditional lumbar discectomy [P < 0.001]. Also, both measures of short-term functional improvement, the Visual Analogue Scale[VAS] and Roland-Morris[RM] scores, were statistically better for microscopic lesionectomy than for traditional discectomy [P < 0.001]. Conclusion : Posterior microscopic lesionectomy can be performed more safely and provide greater benefit than traditional discectomy. The procedure is associated with less post-operative pain, shorter hospital stays, and quicker rehabilitation.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.9
• /
• pp.878-885
• /
• 2009

One of important factors in designing MEMS resonators for RF filters is obtaining a desired frequency response function (FRF) within a specific frequency range of interest. Because various array-type MEMS resonators have been recently introduced to improve the filter characteristics such as bandwidth, pass-band, and shape factor, the degrees of freedom (DOF) of finite elements for their FRF calculation dramatically increases and therefore raises computational difficulties. In this paper the Krylov subspace-based model order reduction using moment-matching with non-zero expansion points is represented as a numerical solution to perform the frequency response analyses of those array-type MEMS resonators in an efficient way. By matching moments at a frequency around the specific operation range of the array-type resonators, the required FRF can be efficiently calculated regardless of their operating frequency from significantly reduced systems. In addition, because of the characteristics of the moment-matching method, a minimal order of reduced system with a prearranged accuracy can be determined through an error indicator using successive reduced models, which is very useful to automate the order reduction process and FRF calculation for structural optimization iterations. We also found out that the presented method could obtain the FRF of a $6\times6$ array-type resonator within a seventieth of the computational time necessary for the direct method and in addition FRF calculation by the mode superposition method could not even be completed because of a data overflow with a half after calculation of 9,722 eigenmodes.

• Journal of Trauma and Injury
• /
• v.29 no.3
• /
• pp.76-81
• /
• 2016

Purpose: The purpose of this study was to compare the data comprehensively including not only the clinical and radiographic outcomes but some parameters related to operation between the minimally invasive plate osteosynthesis (MIPO) technique and intramedullary nailing (IMN) for treatment of segmental tibia shaft fractures. Methods: We conducted a retrospective study of 31 patients (mean age, 49.3 years, range, 27-74 years), with a mean follow-up of 14.1 months (range, 12-19 months) with acute segmental tibial fractures (AO 42-C2) who underwent either surgical treatment of MIPO or IMN. In accordance with the Gustilo-Anderson classification, 11 were type I, 5 were type II, and 15 were type III. Initial compartment syndrome was confirmed in 2 cases. Results: There were no statistically significant differences in terms of the patient demographic data between the two groups. The time to definitive fixation was longer in the MIPO group (mean $13.7{\pm}10.9days$; range, 2-27) than in the intramedullary group (mean $5.4{\pm}9.6days$; range, 0-35) with statistically significant difference (p=0.002). Bony union was observed in most of cases but except 5 cases of nonunion were diagnosed (3 in the MIPO vs 2 in IMN, p=0.188). The average bone healing time was 27.1 weeks (10 to 56 weeks) in MIPO group and 23.2 weeks (13 to 66 weeks) in IMN group, respectively (p=0.056). Overall complications were 5 cases in MIPO group and 2 cases in the IMN group. Difference in LEFS was not statistically significant between both groups (p=0.824). Conclusion: This study showed that segmental tibia shaft fractures treated with both MIPO and intramadullary nailing was challenging with relatively high complication rate. A well planned sequential strategy with keeping the soft tissue and personality of fracture in mind is utmost significant as much as the choice of surgical modalities.

• Archives of Plastic Surgery
• /
• v.33 no.6
• /
• pp.792-796
• /
• 2006

Purpose: After exposure of fracture site, the proximal segment must be reduced to their preinjury position for open reduction of fractured mandibular condyle. We examined the use of inter-maxillary fixation screws or titanium screws tied with stainless steel wire to assist in positioning of proximal segment. Since it enables to make a relatively small preauricular incision by not disturbing the operative field like Moule pin, we can reduce the danger of injury to the facial nerve. Methods: A preauricular approach was used for exposure, reduction, and rigid fixation in 4 cases of mandibular condylar fractures. Inter-maxillary fixation screws or titanium screws tied with stainless steel wire were used to assist in aligning proximal segment. The joints were submitted to functional exercises and postoperative radiologic and clinical follow-ups were performed. Results: No facial nerve lesions were found in all 4 cases. Radiologic follow-up showed correct reduction and fixation in all 4 cases. Clinical follow-up showed an initial limitation, but normal morbility of the condyle was achieved within 4 months after the operation, with a maximum mouth opening of $34.1{\pm}5.2mm$ after 12 months. There found no occlusal disturbances, no trismus, no lateral deviations of the mandible. Conclusion: By using Inter-maxillary fixation screws tied with stainless steel wire, it was shown that reducing the proximal segment to their preinjury position is easy to perform and it enables us to make a minimal dissection below preauricular skin incision to avoid facial nerve injury.

• Korean Journal of Environmental Agriculture
• /
• v.29 no.2
• /
• pp.176-183
• /
• 2010

Endosulfan degrading ability of Klebsiella oxytoca KE-8 immobilized by entrapment with activated carbon was examined. Endosulfan degradation by the immobilized bacterial strains on several different activated carbon based support materials was investigated. Based on results, activated carbon ($8\times30$ mesh) was chosen as a support material. The immobilized Klebsiella oxytoca KE-8 with the cell density of 4 mg $g^{-1}$ (dry weight) degraded 22.18 ug $ml^{-1}$ endosulfan within 5 days at pH 7.0, $30^{\circ}C$ in batch shake flask cultures. Also, we an experimented recycle packed bed column mode and continuous packed bed column mode for endosulfan degradation. Under optimum operation condition, the immobilized cells in a laboratory scale pack bed column with support beads were able to degrade endosulfan completely in defined minimal salt medium at a maximum rate of 129.6 ug $ml^{-1}$ per day. Moreover, the endosulfan degradation activity could be demonstrated at $4^{\circ}C$ for one month without significant decrease in activity. Results of this study suggest that immobilized cells of Klebsiella oxytoca KE-8 might be applicable to endosulfan contaminated site.

• The Korean Journal of Pain
• /
• v.11 no.2
• /
• pp.220-225
• /
• 1998

Background: The patients of facial hyperhidrosis have been known that they had much difficulties in interpersonal relationships and social activities due to excessive hidrosis when they were in stress, hot weather, or having meals. Previous drug therapy and stellate ganglion block have only temporary effects. The surgical method, $T_1$ sympathetomy has the risk of Hornor's syndrome. For that reasons, the sympathicotomy of proximal and distal portions of $T_2$ sympathetic ganglion with electroresectoscope used in transurethral resection seemed to be appropriate procedure, and we would like to report the results of our procedure. Method: Under the general anesthesia with semi-sitting position, and the portal was made through the small incision along the upper border of the 4th rib at the crossing point of mid-axillary line. After the partial collapse of lung by insufflation of 300 to 500 ml of $CO_2$, $T_2$ sympathetic ganglion was identified and resected proximally and distally with electro-cauterization. Finally the lung was expanded by limiting flow until the airway pressure reached 30 to 40 cm$H_2O$, and the wound was closed after removal of electroresectoscope. Result: There was no postoperative complication requiring surgical interventions. The facial sweating was stopped immediately after the operation and all the patients appeared to be satisfied. Conclusion: $T_2$ sympathicotomy with TUR electroresectoscope is thought be the minimal invasive and highly successful method in the treatment of facial hyperhidrosis. But longer terms follow-up will be needed to prove this result.

• The Korean Journal of Pain
• /
• v.11 no.1
• /
• pp.81-85
• /
• 1998

Background: Continuous caudal epidural block is a useful method in postoperative pain control after perianal surgery. But caudal epidural block has the potential of developing adverse effects such as urinary retention. The goal of this study is to evaluate the analgesic and adverse effect of bupivacaine with fentanyl through continuous caudal epidural block in relation to the concentration of bupivacaine. Methods: We divided the patients randomly into two groups. For group I(n=25) postoperative pain was controlled by continuous caudal epidural infusion at the rate of 4 ml/hr of 0.0625% bupivacaine with 3 ${\mu}g$/ml fentanyl: group II(n=14), 0.125% bupivacaine with 3 ${\mu}g$/ml fentanyl, respectively, for duration of 48 hours via epidural catheter. We evaluated pain scores with visual analogue scales at 30 mins, 6 hrs, 12 hrs, 24 hrs and 48 hrs after the operation and the incidence of adverse effect, especially urinary retention, for each group. Results: There were no significant differences in the pain score between group I and II. Urinary retention developed in 9 patients(36%) of group I, and 11 patients (78.6%) of group II. Other adverse effects such as pruritus, nausea, vomiting and respiratory depression developed in few patients. Conclusions: While performing continuous caudal epidural block with mixture of bupivacaine and fentanyl after the perianal surgery, we conclude 0.0625% bupivacaine solution is preferable to 0.125% bupivacaine solution because 0.0625% solution resulted in satisfactory analgesia with minimal incidence of adverse effect.