• Journal of the Korean earth science society
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• v.34 no.6
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• pp.507-514
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• 2013

Recent reports about Mt. Baekdusan indicate an increasing potential of lahar generation due to volcanic activity around Lake Cheonji. In this study, we model lahar assuming volcanic activity underneath the caldera located at the top of Mt. Baekdusan. Lahar-inundation hazard zones (LAHARZ), software that runs within a Geographic Information System (GIS), was used for lahar modeling in various conditions of digital terrain resolution and model parameters. The sensitivity analysis of model parameters shows that both sink threshold and terrain resolution have limited impact on the modeling result. Combinations of stream threshold and resolution indicate distinctive distributions in stream delineation. The limitations of LAHARZ seem to largely be associated with the assumption of an existing flow generation algorithm. However, the impact of different resolutions on the final lahar extent was found to be small.

• Archives of Plastic Surgery
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• v.36 no.3
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• pp.299-305
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• 2009

Purpose: Recently, the incidence of malignant melanoma has been steadily increasing. Malignant melanoma is already known to have poorer prognosis than other primary skin cancers. Despite the poor prognosis, it is relatively less known to the public so that a number of patients visit hospital carrying advanced stage tumor. Yet, extensive study about malignant melanoma is currently insufficient, and specific guidelines and statistical figures in Korea are almost inexistent. Therefore, authors reviewed patients with malignant melanoma who have visited our hospital for last 14 years. Methods: Between January 1994 and January 2008, 62 patients were diagnosed with malignant melanoma at our hospital. A retrospective study was performed with data from patients' charts and biopsy results. Annual incidence, mean age of onset, gender, tumor location, tumor thickness, pathologic ulceration, clinicopathologic subtype, and clinical AJCC stage were evaluated. Analysis of factors associated with survival were performed using the Cox proportional hazard model. Kaplan - Meier method was used to generate survival curves. Results: Clinicopathologic features of 62 patients (32 male, 30 female) with average age of 57 years were evaluated. Most lesions were found in lower limb, and the most common subtype was acral lentiginous melanoma. We could also find that age, tumor thickness, and clinical stage were the only significant prognostic factors. Conclusion: Clinicopathologic features of malignant melanoma were analyzed in this study, but the result is not ready to be generalized because the number of cases is too small. Further study must be performed to report clinical guidelines for prognosis and treatment for malignant melanoma patients in Korea.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.15-20
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• 2018

There have been a number of major fatal fire accidents in Korea recently. The number of fires in 2017 were 44,178, which is not only increasing number of fires but also increasing in casualties. Particularly, the fire at Jecheon Sports Center, which suffered many casualties, is expected to have a huge impact. The cause of the fire has not been determined yet, but heat waves on the ceiling have also been pointed out. As such, the copper heating waves, which are used as a preventive measure against damage of pipes due to freezing of pipes, etc., always have a fire hazard. To determine the possibility of a flame-resistant heated fire, a positive electric cable product was used to artificially ignite and analyze the results. In case of a short circuit, the external covering of the positive electric cable is damaged, but not short circuit unless the heating material surrounding the wire is damaged. Due to the characteristics of heating cable for preventing copper waves, the chances of insulation becoming more severe due to moisture and temperature changes are higher than normal wires. If the internal heating system is carbonized by insulating deterioration without damage to the outer coating, it is likely to cause trekking, to form a winding loop in the heating materials, and to cause short circuit in the heated materials. For the positive temperature line, if the middle is shorted, the current continues to flow to the short circuit unless the breaker disconnects. Consequently, a heated fire that does not cut off the power immediately may leave multiple marks or cuts.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.23-32
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• 2005

Torsional behavior of eccentric structure under seismic leading may cause the stress and/or deformation concentration, which arouse the failure of the structure in an unexpected manner. This study suggests D-R relationship which shows the overall displacement and rotation of the system based on the ultimate displacement capacity of the each lateral load resistant member. Using the suggested D-R relationship and displacement spectrum, the seismic assessment is conducted and verified in comparison with the time history analysis result. Multi-level seismic assessment Is considered which takes multiple seismic hazard levels and respective performance levels into account. Finally, based on the seismic assessment result, seismic rehabilitation process is presented. In this research, two rehabilitation methods are considered. One is done by means of stiffening/strengthening the seismic resistant members, and the other is based on the member ductility. Especially, in the first method, to optimize the rehabilitation result, the rehabilitation problem is modeled as an optimization problem, and solved using BFGS quasi-Newton optimization method.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.370-370
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• 2017

최근 기후변화와 이상기후의 영향으로 인하여 홍수재해의 시 공간적 패턴은 보다 복잡해지고, 예측이 어려워지고 있다. 이러한 기상이변에 따른 홍수피해를 예방하기 위한 비구조적 대책으로 홍수위험등급 및 범람범위 등의 정보를 포함하고 있는 홍수위험지도의 작성이 필요하다. 실제로 고정밀도 홍수위험지도를 작성하기 위해서는 지형, 지질, 기상 등의 디지털 정보 및 사회 경제와 관련된 다양한 DB를 필요로 하며, 강우-유출-범람해석 모델링을 통해 범람면적 및 침수깊이 등의 정보를 획득하게 된다. 하지만 일부지역, 특히 개발도상국에서는 이러한 계측 홍수 데이터가 부족하거나 획득할 수가 없어 홍수위험지도 제작이 불가능하거나 그 정확도가 매우 낮은 실정이다. 따라서 본 연구에서는 ASTER 또는 SRTM과 같은 범용 DEM 등 지형자료만을 기반으로 한 선형이진분류법(Liner binary classifiers)과 ROC분석(Receiver Operation Characteristics)을 이용하여 미계측 유역 (DB부재 또는 부족으로 강우-유출-범람해석 모델링이 불가능한 북한지역)의 홍수위험지역을 탐지하고, 적용성을 평가하고자 한다. 5개의 단일 지형학적 지수와 6개의 복합 지형학적 지수를 이용하여 Area Under the Curve (AUC)를 계산하고, Sensitivity (민감도)와 Specificity (특이도)가 가장 높은 지수를 선별하여 홍수위험지도를 작성하고, 실제 홍수범람 영상(2007년 북한 함경남도지역 용흥강 홍수)과 비교 분석하였다. 본 연구에서 제시하는 선형이진분류법과 ROC분석 방법은 홍수범람해석을 위한 다양한 기초정보를 필요로 하지 않고, 지형정보만을 사용하기 때문에 관측 데이터가 없거나 부족한 지역에 대해서 우선적으로 홍수위험지역을 탐지하고, 선별하는데 유용할 것으로 판단된다.

• International Neurourology Journal
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• v.22 no.4
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• pp.305-312
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• 2018

Purpose: The aim of this study was to analyze the efficacy and to estimate the complication rate of incontinence surgery according to the surgeon's specialty and whether a preoperative urodynamic study (UDS) was performed, using a nationally representative dataset. Methods: We enrolled 356,155 women over 20 years old who had undergone surgery for stress urinary incontinence between 2006 and 2015. Patients were followed for up to 3 years to analyze the reoperation and complication rates. Data were obtained from the National Health Claims Database of the National Health Insurance Service (NHIS) of Korea. Multiple Cox regression analysis was conducted to examine the efficacy and safety of incontinence surgery according to the surgeon's specialty and whether a preoperative UDS was performed. Results: The hazard ratio (HR) for reoperation was significantly higher for procedures performed by nonurologists than for procedures performed by urologists (HR, 1.174; 95% confidence interval [CI], 1.103-1.249). Acute urinary retention, postoperative infections, procedure-associated pain, and other complications were also more common in procedures performed by nonurologists than in those performed by urologists. When stratified by whether a preoperative UDS was performed, the HR for reoperation according to the surgeon's specialty varied by performance of a preoperative UDS. While the reoperation rate was significantly higher in procedures performed by non-urologists when a preoperative UDS was performed (HR, 1.208; 95% CI, 1.122-1.3), there was no significant difference in the HRs for reoperation according to specialty when a preoperative UDS was not performed. Conclusions: This population-based study showed that the postoperative outcomes of incontinence surgery were dependent upon the surgeon's specialty and that the reoperation rate according to the surgeon's specialty varied based on whether a preoperative UDS was performed.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.135-140
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• 2019

Upon chemical agent release, it is of importance to study the characteristic persistence and evaporation of chemical agents from surfaces for the prediction of dispersion hazard. We have recently developed a fast and near real-time wind tunnel system proving the controlled environment(air flow, temperature, and humidity), continuously collects agent vapor and analyzes it. A thermal sorber/desorber is unnecessary to collect the vapor in the system we have developed. Instead, a tandem thermal sorber collects the vapor, which is then directly transferred to a fast gas chromatography(GC) for analysis. As a proof of concept, the evaporation of sulfur mustard agent(HD) was studied from glass, sand and concrete. The results were in an excellent agreement with those obtained from the conventional wind tunnel system.

• Food Science and Industry
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• v.54 no.2
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• pp.62-72
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• 2021

It is necessary to improve the self-management ability of Hazard Analysis Critical Control Point (HACCP) certified companies and intensive management for companies with insufficient management. In addition, the efficiency and convenience of HACCP operation should be improved by expanding and distributing smart HACCP. In this way, it is the direction that HACCP in Korea should go forward to continuously discover and expand the field of application with the improving and smartening the HACCP system.

• School Mathematics
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• v.11 no.3
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• pp.389-413
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• 2009

This thesis assumes that the teaching objective of the Probability unit of the 8th grade textbook under the 7th National Curriculum is to enhance the ability to analyze and utilize informations. And we examine them if this point of view is fully reflected. Based on the analysis of the textbook analysis, followings are found. 1) It is necessary to emphasize more enumerating all possible cases and to induce formulae counting the number of possible cases through organizing them 2) The probability is to be decribed more clearly as a likelihood of events and to be introduced and followed through various students' experiences and the relative frequencies. Less emphasis on probability computations, while more emphasis on probability comparisons of events are recommended. 3) The term "influential events"(a kind of stochastic correlation) is ambiguous. It is necessary to make clear what it means at tile level of the 8th grade or to discard it for it is to be learned at the 10th grade again. Especially, contingency table has been introduced at the 9th grade under the 7th National Curriculum. 4) Uses of the likelihood principle in making a decision and in learning the reliability of it should be encouraged. And students are to team the hazard of transitive inferences in probability comparisons. As a consequence of above, we feel that textbook authors and related stakeholder are to be more serious about the behavioral changes of students that may come along with the didactics of specific contents of school mathematics.

• Fire Science and Engineering
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• v.30 no.6
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• pp.31-36
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• 2016

The flash point is one of the most important properties for characterizing the fire and explosion hazard of liquid solutions. In this study, the flash points of two flammable binary mixtures, n-pentanol + n-propanol and n-pentanol + n-heptanol systems were measured using a Seta flash closed cup tester. The flash point was estimated using the methods based on Raoult's law and multiple regression analysis. The measured flash points were also compared with the predicted flash points. The absolute average errors (AAE) of the results calculated by Raout's law were $1.3^{\circ}C$ and $1.3^{\circ}C$ for the n-pentanol + n-propanol and n-pentanol + n-heptanol mixtures, respectively. The absolute average errors of the results calculated by multiple regression analysis were $0.4^{\circ}C$ and $0.3^{\circ}C$ for the n-pentanol + n-propanol and n-pentanol + n-heptanol mixtures, respectively. According to the AAE, the calculated values based on multiple regression analysis were better than those based on Raoult's law.