• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.78.2-78.2
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• 2010

2008년 6월 14일, 일본 이와테(암수(岩手)) 미야기(궁성(宮城)) 내륙 지진이 발생하였다. 평야지역에서의 피해는 경미하였지만, 산간지역은 괴멸적인 피해를 입은 것이 가장 큰 특정이다. 특히, 산간지역의 간이수도 등, 소규모 수도 시설의 지하수원이 고갈되고 정수시설의 경사면이 붕괴되는 등의 피해를 입었다. 또, 지진발생 후, 원수의 높은 탁도와 색도가 시간이 경과한 시점에서도 낮아지거나 없어지지 않았던 곳이 많았다. 이번 연구보고에서는, 간이수도 등의 피해와 상호지원 체제의 상황을 보고함과 동시에 소규모 수도시설의 지진 재해에 대한 제언을 제시하고자 하였다.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1447-1450
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• 2002

In this paper, we propose a new access method named UR (Use. Relay) scheme to improve the channel efficiency in mobile communications. In UR scheme, packets of a data terminal that do not demand real time communications are relayed by other terminals during their inactive periods, which ue communicating with the base station through a fixed channel at that time. Simulation results show that with UR scheme, the blocking probability md the throughput are improved considerably with an allowable increase in the average delay.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.395-398
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• 2000

The method of Variable Structure Control (VSC) design of windmill power systems is proposed. In the design of sliding mode control, we use Riccati equations arising in linear H$\^$$\infty$/ control to decide a stable sliding surface. Then the reachability to the sliding surface is realized by designing a nonlinear controller for the windmill power system. The capability of the proposed controller to damp out the oscillations of power and the robustness with respect to the system parameter variations and model errors are evaluated in the simulation study.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.324-329
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• 2006

As the average usage period of transformers increases, it is becoming increasingly necessary to know the internal condition of transformers. It is therefore critically important to establish monitoring and diagnostic techniques that can perform transformer condition assessment. Frequency response analysis, generally known as FRA, is one of the technologies to diagnose transformers. Using case studies, this paper presents the effectiveness of FRA as measurements for detecting transformer failures. This paper introduces the fact that FRA waveforms have useful information about diagnosis of failure on core earths and winding shield, and that the condition outside transformers can affect frequency response characteristics.

• Journal of Magnetics
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• v.12 no.2
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• pp.84-88
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• 2007

A micropump with spiral-type magnetic micromachine was fabricated. When a rotating magnetic field was applied, the machine rotated and pumped a surrounding liquid. We experimentally examined the basic properties of this pump. We found that the pressure and the flow rate could be controlled by the rotating frequency, and this pump could work under wide range kinematic viscosity. In addition, we proposed a disposable pump system using the machine. When a plate installed a fluid channel and the machine was set on a stage for generating a rotating magnetic field, the machine worked as the pump.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.687-698
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• 2012

This study was conducted to monitor and prevent outbreak of insect pestsin dredged soil dumping area after completion of dredging construction in Masan City. Monitoring was carried out using tent trap, colored sticky trap, and CDC light trap. A total of 217,073 individuals belonging to 23 species from 10 families in 3 orders were collected. In overwintering survey using tent trap, 3 species were collected. 2 species (Leptocera fuscipennis (Haliday) and Ephydra japonica Miyagi) of them were outbreak species. In color sticky trap, more than 96% of total individuals were comprised of five species: Urolepis maritima Walker (43%), E. japonica (19%), Fucellia sp. 1 (13%), Philotelma sp. 1 (10%), and Homalometopus sp. 1 (9%). In CDC light trap, three dominant species were Homalometopus sp. 1 (91%), Glyptotendipes tokunagai Sasa (6%), and L. fuscipennis (1%), representing about 98% of the total. To prevent damage caused by outbreak of insect pests, we carried out ecological control methods such as covering the fresh soil in outbreak area, using light trap, pumping up water and so on, minimizing use of thermal fogging and insect growth regulatorwhen the insect pest population was rapidly increasing.

• The Korean Journal of Quaternary Research
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• v.18 no.1 s.22
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• pp.31-39
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• 2004

The stable-unstable curve graph (S-U curve) and the ignition los curve graph (IL curve) for pollen composition and inorganic material content in three areas (namely, Kawadoi Basin, Moniwa-Takada moor, and Nenoshiroishi moor) were prepared to reconstruct the recurrence history of slope failure during the Holocene in Northeastern Japan. Through the S-U curve, a period with a high slope failure frequency of 5,600~4,670yrB.P. was identified in Kawadoi Basin, two of 6,390~5,070yrB.P. and 4,750~3,800yrB.P. in Moniwa-Takada moor, and three of 6,630~6,070yrB.P., 5,890~5,360yrB.P., and 5,000~4,650yrB.P. in Nenoshiroishi moor. Through the IL curve, a period with a high slope failure frequency of 5,600~5,140yrB.P. was identified in Kawadoi Basin, and two of 6,390~6,170yrB.P. and 4,750~2,840yrB.P. in Moniwa-Takada moor. Most of above-mentioned periods were included in the period of slope instability in precedent studies. However, the periods with high slope failure frequency in this study were rather different from those in precedent studies. The times and numbers associated with these periods in each study area also showed discrepancies. Accordingly, to achieve the above-mentioned purpose, more case studies must be performed to improve the reconstruction level of slope failure frequency, which could be explained through the analysis of pollen composition and inorganic material content.

• Journal of Marine Life Science
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• v.1 no.1
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• pp.8-17
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• 2016

The family Pristiophoridae belonging to the order Pristiophoriformes consists of about 8 species and 2 genera in the world. Among them, only one species (Pristiophorus japonicus) is distributed in northwestern Pacific. The family is characterized by having an elongated and flattened rostrum with laterally projecting a low of sharp teeth. In order to clarify variability of local populations of P. japonicus, we investigated 16 individuals collected from four locations (Korea, n=6; Miyagi, n=1; Kochi Pref., n=1; Okinawa, n=8) for morphological and molecular analyses. Morphological analysis showed that there may exist three morphotypes, of which A morphotype (Korea, Miyagi, Kochi Pref.) has a short snout (26.8% of TL), being most similar to syntypes of P. japonicus. On the other hand, B morphotype (Okinawa) has a long (31.7% of TL) and wider snout (snout width at nostrils 5.2 times pre-oral length) and, C morphotype (Okinawa) has a long (31.7% of TL) and narrower snout (6.3 times). Molecular analysis using mitochondrial DNA cytochrome b DNA sequences (386 base pairs) showed that the K2P distance between A and C morphotypes were 2.1~2.7%, but those within A morphotype were 0.0~0.5%. We identified A morphotype as P. japonicus, and designated B and C morphotypes as Pristiophorus sp. 1 and Pristiophorus sp. 2, respectively. Further studies are required to elucidate the taxonomic status of two morphotypes of the sawshark in Okinawa.

• International Journal of Control, Automation, and Systems
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• v.1 no.3
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• pp.263-270
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• 2003

This paper deals with a control technique of eliminating the transient vibration of a waist axis of an articulated robot. This technique is based on a model-based control in order to establish the damping effect on the mechanical part. The control model is related to the velocity control loop, and it is composed of reduced-order electrical and mechanical parts. Using this model, the velocity of the load is estimated, which is converted to the motor shaft. The difference between the estimated load speed and the motor speed is calculated dynamically, and it is added to the velocity command to suppress the transient vibration of a waist axis of the robot arm. The function of this technique is to increase the cut-off frequency of the system and the damping ratio at the driven machine part. This control model is easily obtained from design or experimental data and its algorithm can be easily installed in a DSP. This control technique is applied to a waist axis of an articulated robot composed of a harmonic drive gear reducer and a robot arm with 5 degrees of freedom. Simulations and experiments show satisfactory control results to reduce the transient vibration at the end-effector.

• Journal of the Korean Geographical Society
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• v.47 no.5
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• pp.700-717
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• 2012

This study aims to discuss the spatial issues of disaster recovery from the Great East Japan Earthquake. Focused on tsunami-damaged regions, this study examines how major regional development issues have been dealt with. In the case study areas, the following ideal spatial methodologies have been suggested for tsunami recovery: building a compact city, intensifying fishing villages, and making a sustainable city. However, as the spatial restructuring have encountered practical barriers, reconstruction has been delayed, and the regional decline have been accelerating. To prevent regional decline which is inevitable after a disaster, this paper suggests that the area of disaster studies should be expanded to long-term recovery process beyond emergency response.