• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.247-253
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• 2017

Accurate flood frequency and magnitude estimation has a critical role in flood risk management and damage reduction. In United States, Log Pearson Type-III (LP-III) distribution with method of moments for parameter estimation has been uniformly and consistently employed in estimating design floods. After the first version of flood frequency guidelines (Bulletin 15) was published in 1967, the revised version Bulletin 17B has been employed since 1982 up to now. A new version of flood frequency guidelines, Bulletin 17C, is prepared and about to come out soon. In the current study, we analyzed the new features of the upcoming Bulletin 17C and presented case studies applying its new features. From the presented results, we see what critical components in the new design flood frequency guideline we could learn.

• Health Policy and Management
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• v.14 no.2
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• pp.58-77
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• 2004

Cost containment has become high political issues since financial crisis of the Korean Health Insurance fund in 2000. Korean Government has developed and implemented several measures to reduce the pharmaceutical expenditures. Pharmaceutical economic evaluation can be a tool in decision to allocate scare resource efficiently. In order to increase the quality of economic evaluation for pharmaceuticals, the Korean Health Insurance Review Agency(HIRA) is considering the development of a guideline for economic evaluation. It mandates that pharmaceutical companies could submit the result of an economic evaluation when demanding reimbursement of new pharmaceutical drugs. The purpose of this study is to provide a critical review of the economic evaluations of health care technologies published in the Korean context whether they have been performed according to current guidelines and therefore whether their results are directly useful for decision making. We found there exist important problems and deviation from, good practice' both in the general features of the studies, like the study design and perspective, and in terms of cost measurement and valuation. There are needs to develop clear guidelines and to educate and train researchers in performing economic evaluations.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.229-233
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• 2019

Large-scale High Temperature Superconducting (HTS) wind power generators suffer from high electromagnetic force and high torque due to their high current density and low rotational speed. Therefore, the torque and Lorentz force of HTS wind power generators should be carefully investigated. In this paper, we proposed a Performance Evaluation System (PES) to physically test the structural stability of HTS coils with high torque before fabricating the generator. The PES is composed of the part of a pole-pair of the HTS generator for estimating the characteristic of the HTS coil. The 10 MW HTS generator and PES were analyzed using a 3D finite element method software. The performance of the HTS coil was evaluated by comparing the magnetic field distributions, the output power, and torque values of the 10 MW HTS generator and the PES. The magnetic flux densities, output power, and torque values of the HTS coils in the PES were the same as a pole-pair of the 10 MW HTS generator. Therefore, the PES-based evaluation method proposed in this paper can be used to estimate the critical characteristics of the HTS generator under high magnetic field and high torque before manufacturing the HTS wind turbines. These results will be used effectively to research and manufacture large-scale HTS wind turbine generators.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.251-260
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• 2000

Seismic performance evaluation systems require rational classification of structure systems, proper evaluation criteria, and their scoring index for synthesis. Current seismic performance systems need expert judgments based on collection of available data, approximate analysis of important items, and various scoring system. This study presents a three-step seismic performance evaluation system for building structures in Korea. Each evaluation step determines the seismic performance and the method depends on the degree of refinement of analysis. The preliminary step evaluation involves the global attributes of structures such as vertical irregularity, asymmetric plan, redundancy, and age of structures. The second step requires an elastic analysis for estimation of forces acting on critical sections and checks the strength and ductility. The final step requires inelastic capacity of structures. Each stephas own evaluation scheme with proper weighing factor dependent on the importance and consequence. This study applies the fuzzy theory to a scoring method that synthesizes the individual quantity to a representative value.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2430-2434
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• 2011

Dynamic response is an important consideration because of the possibility of resonance according to KTX running over a railway bridges. When KTX runs over the bridge at critical speed, dynamic response is very depending on damping ratio. Current damping ratio for design of high-speed railway bridges adopted EUROCODE without verification of domestic railway bridges. The purpose of this study is to obtain the coherent damping ratio of high-speed railway bridges. Free vibration signal after KTX runs over a high-speed railway bridge was applied. The representative value from distribution of damping ratio was considered.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.1929-1945
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• 2011

RFID technologies have attracted a lot of attention in recent years because of their cost/time-effectiveness in large-scale logistics, supply chain management (SCM) and other various potential applications. One of the most important issues of the RFID-based systems is how quickly tags can be identified. Tag collision arbitration plays a more critical role in determining the system performance especially for passive tag-based ones where tag collisions are dealt with rather than prevented. We present a novel tag collision arbitration protocol called Optimum Frame-Slotted Aloha (OFSA). The protocol has been designed to achieve time-optimal efficiency in tag identification through an analytic study of tag identification delay and tag number estimation. Results from our analysis and extensive simulations demonstrate that OFSA outperforms other collision arbitration protocols. Also, unlike most prior anti-collision protocols, it does not require any modification to the current standards and architectures facilitating the rollout of RFID systems.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.57-64
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• 1999

In order to decide critical vibration level on structural damages induced by near blasting, deformation of existing cracks in structure was investigated and ground vibrations were measured. New criteria to evaluate blasting damage to structure are proposed considering daily deformation of cracks in structures. Results from 2 brick houses in fishing village show that new design criteria far more than current are required to cause structural damage for brick houses.

• Computers and Concrete
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• v.5 no.1
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• pp.37-60
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• 2008

Structural health monitoring of existing infrastructure is currently an important field of research, where elaborate experimental programs and advanced analytical methods are used in identifying the current state of health of critical and important structures. The paper outlines two methods of system identification of beam-like reinforced concrete structures representing bridges, through static measurements, in a distributed damage scenario. The first one is similar to the stiffness method, re-cast and the second one to flexibility method. A least square error (LSE) based solution method is used for the estimation of flexural rigidities and damages of simply supported, cantilever and propped cantilever beam from the measured deformation values. The performance of both methods in the presence of measurement errors is demonstrated. An experiment on an un-symmetrically damaged simply supported reinforced concrete beam is used to validate the developed method. A method for damage prognosis is demonstrated using a generalized, indeterminate, propped cantilever beam.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.687-688
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• 2008

초전도선으로 제작한 초전도기기의 임계전류는 초전도선에 가해지는 자장에 의해 결정된다. 초전도선에 가해지는 자장이 균일하지 않으면 임계전류를 결정하는 자장의 크기를 정하기가 어려워 임계전류를 예측하는 것이 어렵다. 본 논문에서는 초전도선에 인가되는 수직방향과 수평방향의 자장을 고려하여 초전도 권선의 임계전류를 예측할 수 있는 방법을 제시하였다. 제시한 방법으로 단일 팬케이크 권선의 임계전류와 10개의 팬케이크 권선으로 제작된 초전도마그넷의 임계전류를 계산하여 이를 실험결과와 비교하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1116-1117
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• 2015

최근에 개발되고 있는 2세대 고온초전도 선재는 77.3 K의 액화질소보다 높은 임계온도를 가진다. 응용기기의 특성에 따라 액화질소 온도 이하의 다양한 온도 범위에서 운전되고 있다. 이러한 운전 온도의 차이는 초전도 선재의 임계전류 차이를 가져오고, 높아진 임계전류는 시스템의 안정도 측면에서 장점을 가지는 것으로 알려져 있다. 본 논문에서는 다양한 운전 온도 조건에 따른 임계전류에 의한 교류손실 측면의 연구를 진행하였다. 다양한 초전도 권선 형태에서의 임계온도에 따른 교류손실 특성을 수치해석을 통해 확인하고, 시스템의 안정성 향상에 필요한 운전온도에 대한 기본적인 특성 연구를 수행하였다.