• Korean Journal of Head & Neck Oncology
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• v.11 no.1
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• pp.41-46
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• 1995

The pectoralis major myocutaneous flap represents a major contribution to head and neck cancer reconstruction. Its advantages are improved viability, one-stage reconstruction, and carotid protection. The oropharyngeal defect especially tonsillar area reveals valley shaped one with loss of a wide mucosal area. Using pectoralis major myocutaneous flap to this defect is sometimes difficult due to its natural figure of bulkiness. This article reviews our experience with patients undergoing 14 pectoralis major myocutaneous flap in carcinoma of the tonsillar area. Complications and their incidences were I total loss, 3 marginal loss, 2 minor seperation of suture, I wound infection and 2 hematoma. Most of the complications did not require a second procedure for reconstruction. Bulkiness of the flap and gravity force to the upper suture line were thought to be causes of the complications. Modification of the flap design with bilobular figure was useful to reduce its bulkiness at the folding area. More stable suture around hard palate was needed to overcome seperation of the suture.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.11-18
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• 1985

A row of bored piles has been used in several excavation works to retain the earth. This excavation bracing system has much effect on low-vibration and low-noise during construction. The system is also effective to provide protection to the adjacent existing ground and structures. For the purpose of establishment of a logical design method for the bored piles, first, a theoretical equation to estimate the resistance of piles is derived. Because arching action of soils between piles is considered in the equation, the characteristics of soils and the installation condition of piles would be considered logically from the beginning. Then a method is investigated to decide the interval ratio of piles. According to the method, the interval between piles can be decided from the information of the Peck's stability number, the coefficient of lateral earth pressure and the internal friction angle of soil. Finally, a design method is presented for the bored piles used for excavation work. In the presented design method, such factors as depth of excavation, pile diameter, interval between piles, pile length below bottom of excavation and pile stiffness, can be selected systematically.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.101-113
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• 2007

A landslide was occurred due to soil cutting for construction to expand the Donghae express highway in Dong-hae-City, Korea. The total area of the landslide was about $9,550m^2$ with 100 m of width and 87m of height. The landslide was occurred due to the internal factor of the unstable geological structure including the clay layer and the external factor of continuous heavy rainfalls. As the result of field instrumentation during the landslide, the horizontal displacement of the slope ground increases with increasing the accumulated rainfall by continuous rainfall during the rainy season. Also, the depth of sliding failure was decided by the horizontal displacement distribution during landslide occurrence. It makes sure that the horizontal displacement starts from the depth of sliding failure and the depth of sliding failure matches well with the location of the clay layer. As the slope stability analysis using Bishop's Simplified Method at the landslide area, the safety factor of slope during the rainy season was 0.53. This safety factor of slope was enough to trigger the landslide at this area. The depth of sliding failure obtained by analytical method matches well with the depth of the clay layer.

• The Journal of Engineering Geology
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• v.18 no.1
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• pp.17-26
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• 2008

In this study, the design method of slope reinforced by the earth retention systems were systematically developed, and the flow chart of design procedure fur each system were constructed to design the slope rationally. The proposed design method is composed of 5 steps such as field condition investigation step, slope design step, landslide occurrence prediction step, slope failure scale estimation step and reinforcement countermeasure selection step. The quantitative standard of slope failure scale was established based on the arrangement of various overseas standards which is estimating the slope failure, and the analysis of slope failure scale which is occurred in the country. The slope failure scale is classified into three categories the small scale of slope failure is less than $150m^3$ of slope failure volume, the middle scale of slope failure is from $150m^3$ to $900m^3$ and the large scale of slope failure is more than $900m^3$. The earth retention system could be selected by the proposed slope failure scale based on the slope failure volume. Meanwhile, the design methods of earth retention system such as piles, soil nails and anchors were developed. The optimal countermeasure for slope stability could be proposed using above design methods.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.28-33
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• 2020

Recently, the overseas construction market has been actively promoted for about 10 years, and overseas dam construction has been continuously performed. For the economic and safe construction of the dam, it is important to prepare the main dam construction plan considering the design frequency of the diversion tunnel and the cofferdam. In this respect, the prediction of river level during the rainy season is significant. Since most of the overseas dam construction sites are located in areas with poor infrastructure, the most efficient and economic method to predict the water level in dam construction is to use the upstream water level. In this study, a linear regression model, which is one of the simplest statistical methods, was proposed and examined to predict the downstream level from the upstream level. The Pyeongchang River basin, which has the characteristics of the upper stream (mountain stream), was selected as the target site and the observed water level in Pyeongchang and Panwoon gaging station were used. A regression equation was developed using the water level data set from August 22th to 27th, 2017, and its applicability was tested using the water level data set from August 28th to September 1st, 2018. The dependent variable was selected as the "level difference between two stations," and the independent variable was selected as "the level of water level in Pyeongchang station two hours ago" and the "water level change rate in Pyeongchang station (m/hr)". In addition, the accuracy of the developed equation was checked by using the regression statistics of Root Mean Square Error (RMSE), Adjusted Coefficient of Determination (ACD), and Nach Sutcliffe efficiency Coefficient (NSEC). As a result, the statistical value of the linear regression model was very high, so the downstream water level prediction using the upstream water level was examined in a highly reliable way. In addition, the results of the application of the water level change rate (m/hr) to the regression equation show that although the increase of the statistical value is not large, it is effective to reduce the water level error in the rapid level rise section. Accordingly, this is a significant advantage in estimating the evacuation water level during main dam construction to secure safety in construction site.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.131-143
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• 2000

Several theoretical analyses are performed to predict the vertical load on embankment piles with cap beams. The piles are installed in a row in soft ground below the embankment and the cap beams are placed perpendicular to the longitudinal axis of the embankment. Two failure mechanisms such as the soil arching failure and the punching shear failure are investigated according to the failure pattern in embankment on soft ground supported by piles with cap beams. The soil arching can be developed when the space between cap beams is narrow and/or the embankment is high enough. In the investigation of the soil arching failure, the stability in the crown of the arch is compared with that above the cap beams. The factors affecting the load transfer in the embankment fill by soil arching are the space between cap beams, the width of cap beams and the soil parameters of the embankment fill. The portion of the embankment load carried by cap beams decreases with increment of the space between cap beams, while it increases with the embankment height, the width of cap beams, the internal friction angle and cohesion of the embankment fill. Thus, the factors affecting load transfer in embankment should be appropriately decided in order to maximize the effect of embankment load transfer by piles.

• Korean Journal of Head & Neck Oncology
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• v.12 no.2
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• pp.217-223
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• 1996

A retrospective analysis was performed to assess the relationship between the treatment modalities and treatment results in patients with adenoid cystic carcinoma of the maxillary sinus. From Feb. 1977 to March 1994, 10 patients with the disease were treated at the Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine. Six men and 4 women were presented with median age of 57 years. According to AJCC TNM system, all patients except one had advanced T3 and T4 disease. Only one patient had the regional metastasis to lymph node but none of them had hematogenous metastasis on initial admission. One patient(Group 1) was treated with surgery alone, 3 patients(Group 2) were treated with definitive radiotherapy and 6 patients(Group 3) were treated with combination of surgery and radiotherapy. One patient who was treated with surgery alone had experienced a locoregional recurrence 9 months later and 3 patients who were treated with radiation therapy alone had PRs(partial response) followed by the subsequent progression of the local disease. Whereas all patients who were treated with combination of surgery and radiation therapy had CRs(complete response). Among them, only one patient was recurred in the primary site, who was salvaged by reoperation and reirradiation therapy. In conclusion, combination of surgery and radiotherapy resulted in the best treatment modality for adenoid cystic carcinoma of the maxillary sinus. Improved radiotherapy technique and development of multimodality treatment are needed to improve the local control and the survival rate in patients with advanced adenoid cystic carcinoma of the maxillary sinus.

• Korean Journal of Head & Neck Oncology
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• v.14 no.1
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• pp.40-45
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• 1998

Backgroud and Objectives: Major salivary gland tumor is a rare disease with a largely unknown origin. And also corresponding to the diversity of histopathologic characteristics is an equally wide distribution of clinical behavior that makes treatment decisions difficult. The aim of this study is to analysis the clinical experience of our major salivary gland tumor and to suggest a guidline of management. Materials and Methods : We studied clinical manifestations and treatment results of 104 patients who were diagnosed as major salivary gland tumors. Tumor site, patient age and sex of the patients were analysed. Histopathologic diagnosis, treatment modality, lymph nodes metastasis, recurrence rate and 5-year survival rate were studied on malignant tumors. Results: 1) 48 patients were male and 56 patients were female. 2) Benign tumors were 79 cases. They consisted of 57 cases(72%) of parotid tumor, 22 cases(27%) of submandibular tumor. And pleomorphic adenoma was the most common benign tumor. 3) Malignant tumors were 25 cases and were consisted of 19 cases(76%) of parotid tumor, 4 cases(l6%) of submandibular tumor and 2 cases(8%) of sublingual gland tumor with high-grade mucoepidermoid carcinoma as the most common cause. 4) In the malignant tumors, the number of stage I, II tumors was 14 and that of stage III, IV tumors was 11. Neck node metastasis was noted in 8 cases. 5) 8 cases of malignant tumor were died and all of them had high-grade malignancy. And they were dead before 17 months from the time of diagnosis. 6) Mean survival duration in the malignant salivary gland tumor was 56 months. 7) High-grade malignancy had a 5-year survival rate of 57.9%. A 5-year survival rate of TI, T2 patients was 92.9% and that of T3, T4 patients was 36.4%. That of patients who had neck node metastasis was 37.5% and that of those who had tree neck was 82.4%. Conclusion: The results of this study suggest that the survival rate is dependent on the tumor size, lymph node matastasis and histologic grade. And also the early diagnosis and radical surgery result in the increased survival rate and are effective for prevention of the tumor recurrance.

• Korean Journal of Head & Neck Oncology
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• v.14 no.1
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• pp.46-53
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• 1998

Background: Hypopharyngeal cancer represents about one-third the incidence of laryngeal cancer which is the most common cancer in head and neck area. Although there have been numerous reports regarding its clinical and statistical characteristics, more precise and ample data should be collected and analyzed in this country. Objectives: This study was designed to evaluate the pattern and patient's profile of the hypopharyngeal cancer, and we reviewed the treatment outcomes to search for an index of treatment modalities. Materials and Methods: The authors retrospectively analyzed 73 cases of hypopharyngeal cancer treated at Yonsei Medical Center during the 10-year period from 1985 to 1994. Five-year survival rate was calculated according to the primary site, clinical stage and treatment modality. Results: The incidence was predominated in male by 9 to 1 and peak incidence was 6th and 7th decades. Pyriform sinus was the main primary site(80.8%) followed by posterior hypopharyngeal wall(13.7%) and postcricoid area(5.5%). Advanced stage cancers(87.7%) were more common than early stage cancers. Radiotherapy(60.3%) was the most commonly used as primary treatment modality. Neck node metastasis was early occurred even in early stage cancers(61.5%), and overall rate of neck node metastasis was 69.9%. All surgical cases received procedures more than total laryngectomy and partial pharyngectomy. The most common cause of death was primary failure(81.5%) and it was highest in radiotherapy group. Five-year survival rate was significantly high in surgery group(90.9%). The overall 5-year survival rate of hypopharyngeal cancer was 30.3%. Conclusion: High index of suspicion should be required for early diagnosis. Also, surgery may be recommended for the primary treatment modality in advanced stage cancers.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.67-75
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• 2004

The landslide is one of the most significant natural disasters, which cause a lot of loss of human lives and properties. The landslides in natural slopes generally occur by complicated problems such as soil properties, topography, and geology. Artificial Neural Network (ANN) model is efficient computing technique that is widely used to solve complicated problems in many research fields. In this paper, the ANN model with application of error back propagation method was proposed for estimation of landslide hazard in natural slope. This model can evaluate the possibility of landslide hazard with two different approaches: one considering only soil properties; the other considering soil properties, topography, and geology. In order to evaluate reasonably the landslide hazard, the SlideEval (Ver, 1.0) program was developed using the ANN model. The evaluation of slope stability using the ANN model shows a high accuracy. Especially, the prediction of landslides using the ANN model gives more stable and accurate results in the case of considering such factors as soil, topographic and geological properties together. As a result of comparison with the statistical analysis(Korea Institute of Geosciences and Mineral Resources, 2003), the analysis using the ANN model is approximately equal to the statistical analysis. Therefore, the SlideEval (Ver. 1.0) program using ANN model can predict landslides hazard and estimate the slope stability.