• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.660-665
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• 2004

본 연구에서는 비선형적인 메커니즘을 갖는 수문현상의 불확실성을 해석하고자 하는 목적으로 새로운 개념의 지배방정식이 유도된다. 제안된 모형의 불확실성은 토양 특성치의 공간적 변동성에 기인하고 있는 것으로 가정하여, 유도된 방정식은 Fokker-Planckl 방정식의 형태를 가지고 있다. 실제 유역단위에서 토양 내 수분 흐름의 연직방향 흐름을 모의하기 위해 미소단위에서 유도된 Richards 방정식은 토양의 공간적 변동성으로 말미암아 불확실한 매개변수를 갖는 비선형 추계학적 편미분방정식의 형태를 갖게 된다. 이는 먼지 수직 방향적분을 통하여 단순화된 비선형 추계학적 상미분방정식으로 전환되고, 이렇게 전환된 비선형 추계학적 상미분방정식은 다시 추계학적 Liouville 방정식을 이용하여 선형 추계학적 편미분방정식으로 전환되어진다. 최종적으로 cumulant 급수방법을 이용하여 상기 방정식을 선형 결정론적 편미분방정식으로 전환시킴으로써, 강우 시 토양 내 수분 침투현상을 모형화할 경우 유역단위에서 토양의 공간적 변동성을 설명할 수 있는 지배방정식을 유도할 수 있다.

• Korean Journal of Ichthyology
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• v.6 no.2
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• pp.206-221
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• 1994

Morphometrical data for diploid and induced triploid cherry salmon, Oncorhynchus masou were analyzed prior to the spawning season to compare their commercial values. The following traits were measured with the diploids and induced triploids : ungutted and gutted body weight; body length; dressing percentage; condition factor; gonad weight and gonad index; belly thickness; viscera weight; viscera index; body circumference at the pelvic, dorsal and anal fins; area of the cross sections at the pelvic and dorsal fins; two belly thickness traits measured on each cross section; total height, height and width of each cross section; three body shape traits; and nine cross section shape traits. Body length and body weight of diploids were larger than those of induced triploids and dressing percentage, gonad weight, gonad index, viscera index, and liver index were also larger in diploids. However, induced triploids showed higher values in one belly thickness trait and some section shapes than diploids. Differences in body traits were due to the sterility of induced triploids. Therefore, induced triploid cherry salmon appears to have greater potentials for the commercial values than their diploids.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.5
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• pp.51-59
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• 1993

이중여자 유도전동기의 두 3상 시스템중 하나는 직접 전원에 접속되어서 에너지 변환을 담당하고 다른 3상 시스템은 전류의 크기나 주파수를 제어할 수 있는 인버터에 접속되었다. 단일여자 모드에서 운전되는 기계는 유도모드만 가능하나 이중여자 모드에서 운전되는 기계는 유도모드와 동기모드 둘 다 가능하다. 동기모드에서 운전되는 이중여자 유도전동기의 효율은 유도모드나 기존의 유도전동기 보다 높으며 속도 제어용 인버터 정격은 일반적으로 기계정격보다 크지만 이중여자 시스템에서는 기계 정격의 일부로 가능하다. 동기모드에서 속도는 인버터 출력전류의 크기나 주파수를 가변함으로서 제어될 수 있으며 이중여자 유도전동기를 가변속도 시스템에 사용하면 다른 전기기계의 사용에 비해 유지보수비와 가격을 감소시킬 수 있다.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.3-5
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• 2018

유도 가열 (Induction Heating; IH) 기기는 빠른 가열 속도, 안전성, 청결성 등의 장점으로 산업계와 가정에서 널리 사용되고 있다. 하지만 기존 IH 기기는 낮은 저항을 갖는 비자성체 용기를 가열할 때 1차측 스위치에 높은 전류가 유도됨으로써 스위칭 손실과 전도 손실이 증가하고 스위치 정격 전류량을 초과하는 문제가 발생하였다. 본 논문에서는 용기 재질에 따른 임피던스 특성을 분석하여 비자성체 용기를 가열하기 위한 적절한 유도 가열용 직렬 공진형 컨버터의 새로운 스위칭 변조방식을 제안한다. 2 kW의 정격 전력을 가지는 유도 가열용 컨버터의 시작품을 사용하여 설계 방법론과 스위칭 변조 방식의 타당성과 성능을 검증하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.471-479
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• 2004

In this study, a time-dependent constitutive model was developed for cohesive soils. A damage law was included in the model, using which the undrained creep behavior was predicted. The mathematical and physical derivation of the model was performed in the sense of adopting only few model parameters. The model prediction was well agreed with the experimental result of creep testing including creep rupture.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.179-184
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• 2008

Silt or clay alluvium fully saturated with water generally shows low resistivity. Sometimes it is believe that the low resistivity layer is considered as good aquifer but this makes problems in the development of groundwater. To overcome this problem, we adopted induced-polarization(IP) method with resistivity method. Laboratory experiments and resistivity/IP field surveys with non-polarization electrodes were conducted for the study. Laboratory experiments shows that the increase of clay contents in the sample mixed with sand and clay give low resistivity and high chargeability. We used this experiment results in the interpretation of resistivity/IP field data which were obtained in riverbank filtration. Finally, the layer which has low resistivity and chargeabilty would be regarded as a good aquifer for the development of groundwater intake.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.54-61
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• 2001

Magnetostrictive materials have nonlinear elasto-magnetic properties. However the constitutive equations to describe the nonlinear properties are not available, yet. In this study we develope the equation in magnetostrictive materials by use of piezomagnetic constitutive equation which is quasi-linearized. With the wave equation, we determine the propagation velocity inside the magnetostrictive materials when a plane wave propagates along a given magnetic field. Validity of the calculated velocity is verified through comparison with experimental velocity measurement results for the most representative magnetostrictive materials. Terfenol-D.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.4
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• pp.391-397
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• 2001

The guided wave propagation in inhomogeneous multi-layered structures is experimentally explored based on theoretical dispersion curves. It turns out that proper selection of incident angel and frequency is critical for guided wave generation in multi-layered structures. Theoretical dispersion curves greatly depend on adhesive zone thickness, layer thickness and material properties. It was possible to determine the adhesive zone thickness of an inhomogeneous multi-layered structure by monitoring experimentally the change of dispersion curves.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.574-581
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• 2019

This paper investigates the effects of thrust misalignments and offsets of the lateral center of gravity of a space launch vehicle on its guidance performance. Sensitivity analysis and Monte Carlo simulations are applied to analyze their effects by computing changes in orbit injection errors when including the error sources. To compensate their effects, the attitude controller including an integrator additionally and the Steering Misalignment Correction (SMC) routine of the Saturn V are considered, and then Monte Carlo simulations are performed to evaluate their performances.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.201-208
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• 2020

This study examined the anti-obesity effect of krill oil (KO) by regulating adipokines in a high-fat diet (HFD)-induced obese mouse model. The mice were fed a 60 kcal% HFD for 16 weeks, and KO was then administered at an oral dose of 100, 200, and 500 mg/kg/day for four weeks before the end of the experiment. The administration of KO at concentrations of 200 and 500 mg/kg/day decreased body weight gain significantly compared with the HFD-fed control group. In addition, the HFD-fed control group showed the abnormal release of adipokines by an increase in leptin and decrease in adiponectin, compared to the normal diet-fed normal group. On the other hand, KO (500 mg/kg/day)-administered group attenuated the abnormal release of adipokines by the down-regulation of leptin and the up-regulation of adiponectin. Therefore, KO could be a promising therapeutic agent for obesity by the regulation of adipokines.