• Knowledge Management Research
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• v.19 no.2
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• pp.151-162
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• 2018

Response surface methodology (RSM) is one of popular tools to support a systematic improvement of quality of design in the product and process development stages. It consists of statistical modeling and optimization tools. RSM can be viewed as a knowledge management tool in that it systemizes knowledge about a manufacturing process through a big data analysis on products and processes. The conventional RSM aims to optimize the mean of a response, whereas dual-response surface optimization (DRSO), a special case of RSM, considers not only the mean of a response but also its variability or standard deviation for optimization. Recently, a posterior preference articulation approach receives attention in the DRSO literature. The posterior approach first seeks all (or most) of the nondominated solutions with no articulation of a decision maker (DM)'s preference. The DM then selects the best one from the set of nondominated solutions a posteriori. This method has a strength that the DM can understand the trade-off between the mean and standard deviation well by looking around the nondominated solutions. A posterior method has been proposed for DRSO. It employs an interval selection strategy for the selection step. This strategy has a limitation increasing inefficiency and complexity due to too many iterations when handling a great number (e.g., thousands ~ tens of thousands) of nondominated solutions. In this paper, a TOPSIS-based method is proposed to support a simple and efficient selection of the most preferred solution. The proposed method is illustrated through a typical DRSO problem and compared with the existing posterior method.

• Advances in pediatric surgery
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• v.2 no.2
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• pp.102-109
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• 1996

Pediatric surgeons are familiar with the posterior sagittal approach to the rectum at sacrococcygeal area and well oriented with the anatomy because of the Penal procedure for imperforate anus. The author utilized the posterior vertical elliptical incisions in 12 cases of sacrococcygeal teratoma since 1987. For presacral tumor(type IV)$^2$, the incision was exactly same as the posterior sagittal procedure for imperforate anus. But the out-growing(type I) or dumbbell-shaped(type II & III) tumors, a vertical elliptical incision was required. For the laterally deviated tumors, a vertical and half-chevron incision was utilized in one case, but an unbalanced vertical elliptical incision was acceptable for the remaining two cases, with shrinkage of the overlying skin. In dumbbell-shaped tumors(type II & III), the narrow waist of the tumor was at the level of the levator muscle, which formed a muscle-belt on the tumor waist. A careful dissection to save the muscle-belt seemed to be the most important point during this procedure, utilizing the nerve-stimulator. After complete removal of the tumor and the coccyx, the levator muscles and the skin were closed in vertical fashion along the midline. For the caudally extending tumors in 3 cases, the muscle complex was divided in midline. Nothing by mouth and total parenteral nutrition was maintained for 1 week and then laxatives were given for 2 weeks in order to give the sphincters rest. Operative scars were acceptable resembling natural vertical midline folds, and the sphincter function was continent in all cases. In conclusion, vertical elliptical incision in sacrococcygeal teratoma is recommended because of the acceptable scar, functional restoration, and because it is a familiar procedure particularly for the pediatric surgeons who are accustomed performing posterior sagittal approach for imperforate anus.

• Korean Journal of Head & Neck Oncology
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• v.10 no.2
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• pp.128-136
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• 1994

Maxillary cancer is usually detected late, and the majority of patients have advanced($T_3\;or\;T_4$) diseases at the first diagnosis. It invades outside the maxillary antrum, superiorly the orbit, ethmoid sinus and the anterior cranial base, anteriorly the facial skin. If the cancer extends through the posterior antral wall, the pterygoid plates, pterygoid muscles and infratemporal fossa are to be involved that make the conventional maxillectomy impossible to remove all the involved structures in infratemporal fossa completely. So, more extensive surgical apprdoach is necessary. We report surgical experience using infratemporal fossa approach(lateral facial approach) in four cases of maxillary cancer and one case of hard palate cancer which extends through the posterior antral wall and involving pterygoid muscles, pterygoid plates and temporalis muscle.

• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.647-654
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• 2003

Bayesian probability models for finite populations are considered assuming so-called the super-population. We find the posterior distribution of population mean by a new approach, using the concept of pivotal quantity for the small sample case. A large sample theory is also treated throught the concept of asymptotically pivotal quantity.

• IE interfaces
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• v.6 no.2
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• pp.79-89
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• 1993

We develop a statistical model to describe nuclear power plant accidents and predict time to next accident of various levels. We adopt Bayesian approach to obtain posterior and predictive distributions for the time to next accident. We also derive an approximation method to solve many dimensional numerical integration problems that we often encounter in a Bayesian approach. We introduce Influence Diagrams in modeling, and parameter updating, thereby the dependency or independency among model parameters are clearly shown. Also Separable Updating Theorem is utilized to easily obtain the posterior distributions.

• Journal of Korean Neurosurgical Society
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• v.29 no.1
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• pp.118-125
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• 2000

Objective : Trigeminal neurinomas are rare tumors that may locate in the middle fossa or posterior fossa and straddled both the middle and posterior fossa, according to their origin in the nerve complex. The aim of this study was to analyze the clinical presentation, operative approaches employed and outcome in 15 patients who were treated surgically, with special emphasis on surgical approach. Method : Between 1994 and 1998, a total of fifteen patients were histopathologically identified as neurinomas originating from the trigeminal nerve complex at the tumor clinic in the neuroscience center of the our university. Results : The surgical approach to these tumors depends on their anatomical location and tumor size. Six patients had tumors confined to the middle fossa, five patients had tumors limited to the posterior fossa, and four patients both in middle and posterior fossa components of their tumors. Nine neurinomas were removed via the conventional approach(pterional, subtemporal, suboccipital) and six were excised using skull base approach(transzygomatic subtemporal, orbitozygomatic, transpetrosal). Total resection of the tumor was possible in 10 cases. Total resection of tumor was accomplished in 83% of patients following skull base approach compared with 56% of patients following conventional approach. The surgical outcome was excellent or good in 13 cases, fair in one and, poor in one. There was no operative death. In the immediate postoperative period, aggravation of preoperative facial hypesthesia and 6th cranial nerve palsy were common. Although, these deficits were generally transient, eight patients remained with some degree of trigeminal hypesthesia, two had facial weakness, one neurotrophic keratitis, one diplopia, and one mastication difficulty. Conclusion : Surgical approach to the trigeminal neurinoma depends on the tumor location and tumor size. Skull base approach provides more complete tumor excision without increased morbidity compared to conventional approach. Surgeons have to be meticulous in order to reduce postoperative complication.

• The Journal of the Korean bone and joint tumor society
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• v.8 no.3
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• pp.76-82
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• 2002

Purpose: Benign bone tumor of the talar body have rarely been evaluated according to the therapeutic methods because of the scarcity of their incidence. Here, we report our experience of 8 cases who were treated by using of posterior approach and curettage through the posterior process of the talus. Materials and Methods: Between February 1986 and October 2001, we experienced 8 cases of benign bone tumor occurring in the talar body. They included two osteoid osteomas, two giant cell tumors, one capillary hemangioma, one chondroblastoma, one simple bone cyst, and one osteochondroma. Their mean age was 22.1 years (ranging from 10 to 41 years). Mean follow-up period was 7.7 years (ranging from 1 to 16 years). All patients were treated by using of posterior approach. Two osteoid osteomas and one osteochondroma were treated by excision of tumors. Other cases were treated with curettage through the cortical window on the posterior process of the talus. Results: There was no recurrence during the follow-up period. one infection occurred. Except this case, all patients had no pain in weight-bearing, and complete range of movement at the ankle joint was reserved in each case. Conclusion: In this study, we suppose that posterior approach to the talar body may be a safe method with minimal damage of normal tissues and sufficient of curettage is capable through the cortical window on the posterior process of the talus.

• Korean Journal of Head & Neck Oncology
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• v.12 no.2
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• pp.193-200
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• 1996

We performed a retrospective study to evaluate the effect of posterior approach to facial nerve in parotid surgery, being the standard procedure in our hospital, on postoperative facial palsy and to access the safety of this procedure in preserving the function of facial nerve. A series of 176 parotid surgeries from 172 patients from January 1989 to December 1994 was analyzed, of which, 2 Schwannomas, 4 Kimura's diseases, 6 preoperative facial palsies, and 4 intentional nerve resections for malignancy were excluded. Factors such as pathology of tumor, extent of surgery, location of tumor, size of tumor, frequency of surgery were reviewed to determine if any factor contributed to the developement of facial palsy postoperatively. Of 160 parotidectomies, postoperative facial palsy was found in 58(36.3%), being temporary in 35(35. 6%), recovered within 12 months after surgery and permanent in 1(0.6%). Facial palsy occured in 47(35.7%) of 128 benign tumors, 42(89.5%) recovered completely within 6 months and in 11(34.4%) of 32 malignant tumors, 6(54.5%) within 6 months. Among the factors analyzed, postoperative facial palsy was found to be common in the tumors of deep lobe(p<0.02) and in total or neartotal parotidectomies(p<0.08). In our study, the factors of the location of tumor and extent of surgery would be contributable to developement of postoperative facial palsy and the surgical technique using posterior approach to the facial nerve may be a simple and safe surgical procedure for identification and preservation of facial nerve in parotid surgery.

• Korean Journal of Head & Neck Oncology
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• v.26 no.2
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• pp.253-255
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• 2010

Identification and protection of the facial nerve is very important in the proper operation of the parotid tumor. Posterior approach which finds main trunk of the facial nerve by surgical landmark such as tragal pointer, tympanomastoid suture, and posterior belly of digastric muscle is most commonly used. In case of posterior located tumor, inferior approach may be used, in which the retromandibular vein is followed from the neck and inferior branch of the facial nerve is located. In general, the facial nerve lies superficial to the retromandibular vein. But we experienced the anomalous relationship of the facial nerve and the retromandibular vien. We report this case with a literature review.

• Journal of Korean Neurosurgical Society
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• v.37 no.4
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• pp.310-312
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• 2005

We report a case of endodermal cyst of the posterior fossa. A 44-year-old man presented with headache for three months. Computed tomography and magnetic resonance imaging revealed a $6{\times}2.5{\times}2cm$ sized extra-axial non-enhancing cystic lesion on the ventral aspect to brain stem. To avoid retraction injury to brain stem, far lateral transcondylar approach was selected. Right suboccipital craniotomy and partial removal of occipital condyle with resection of C-1 and C-2 hemilaminae exposed the extra-axial cyst well. The cyst has a whitish thick membrane. It was not adherent to brain stem and lower cranial nerves. Total removal of the cyst was done without difficulty. Histological analysis disclosed a layer of pseudostratified columnar epithelium with basement membrane. The result of immunohistochemical study was consistent with endodermal cyst.