• Economic and Environmental Geology
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• v.51 no.5
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• pp.463-471
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• 2018

In this paper, we review previous studies on the relative sea-level changes in the Yellow Sea during the Holocene to comprehensive understand the various research results. Currently, it is reported two theories : 1) the Holocene sea-level has never been higher than the present-day level; and 2) sea-level have reached highstand during mid-Holocene, followed by slow lowering to that of the present. The first theory yields a curve that is similar to a climate-change-related eustatic sea-level curve. However, in reality, most of the relative sea-level fluctuation resulted from land uplift or subsidence. The second theory yields a curve that is fairly coincident with a relative sea-level curve indicative of continental margins being located away from the ice sheets(i.e., far-field), and is considered as an effect of GIA(Glacio Isostatic Adjustment) and gravitational attraction. Based on detailed review of previous researches, we realized that they sourced the same papers, but obtained different results because they selectively chose and added the data. The data used to derive the second theory pertain to the northern Gunsan region, which is located within the western area of the Chugaryeong fault. Thus, we believe that the sea-level curve for the second theory is only representative of the area north of Gunsan, which is subject to GIA and tectonic deformation. Although the relative sea-level curve for the west coastal area is comparable to that for the far-field continental margin region, it is necessary to evaluate local tectonic activities as suggested by active seismicity in the west coastal area and the more than 400 faults currently existing in on the Korean Peninsula.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.802-808
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• 2019

DC motors are used extensively on shipboard, including as the ship's winch operating motor, owing to their simple speed control and excellent output torque characteristics. Moreover, they were used as propulsion motors in the early days of electric propulsion ships. However, mechanical rectifiers, such as brushes, used in DC motors have certain disadvantages. Hence, brushless DC (BLDC) motors are increasingly being used instead. While the electrical characteristics of both types of motors are similar, BLDC motors employ electronic rectifying devices, which use semiconductor elements, instead of mechanical rectifying devices. The inverter system for driving conventional BLDC motors uses a two-phase excitation method so that the waveform of the back electromotive force becomes trapezoidal. This causes harmonics and torque ripple in the phase current switching period in which the winding wire through which the current flows is changed. Researchers have studied and presented various methods to reduce the harmonics and torque ripple. This study applies a cascaded H-bridge multilevel inverter, which implements a proportional-integral speed current controller algorithm in the driving circuit of the BLDC motor for electric propulsion ships using a power analysis program. The simulation results of the modeled BLDC motor show that the driving method of the proposed BLDC motor improves the voltage waveform of the input side of the motor and remarkably reduces the harmonics and torque ripple compared with the conventional driving method.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.196-215
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• 2007

The Representatives of Korea & India hold The Sixth negotiation for conclusion of Korean-India CEPA(Comprehensive Economic Partnership Agreement) at IFANS(Institute of Foreign Affairs & National Security) in Seoul at April 4, 2007. The latest, India is paid attention by the citizen of the world as the leading country that it lead the 21C's world economic with the China, India is called one of the BRICs and Chindia countries. Now, the concern of the citizen of world inclines huge potential energy of India. It is that time, we must change our concern from Chinas to India slowly. This paper put emphasis the point that we have to move switch over the focus of our study from to India, now.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.69-74
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• 2009

In Korea, large amounts of chestnut shell as by-products are produced from food industries. However, most of the by-products exist with no disposal options. Biosorption uses biomass that are either abundant or wastes from industrial operations to remove toxic metals from water. Objective of this research was to evaluate the feasibility of using chestnut shell as by-products for removal of metal ions(Pb, Cu and Cd) from aqueous solution. The chestnut shell was tested for its efficiency for metal removal by adopting batch-type adsorption experiments. The adsorption selectivity of chestnut shell for metals was Pb > Cu > Cd at solution pH 5.5. The Langmuir isotherm adequately described the adsorption of chestnut shell for each metal. Using The maximum adsorption capacity predicted using Langmuir equation was 31.25 mg $g^{-1}$ 7.87 mg $g^{-1}$ and 6.85 mg $g^{-1}$ for Pb, Cu and Cd, respectively. Surface morphology, functional group and existence of metals on chestnut shell surface was confirmed by FT-IR, SEM and EDX analysis. The chestnut shell showed an outstanding removal capability for Pb compared to various adsorbents reported in the literatures. The overall results suggested that chestnut shell might can be used for biosorption of Pb from industrial wastewater.

• Economic and Environmental Geology
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• v.46 no.2
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• pp.165-178
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• 2013

This study is for the genetic differences of two closed asbestos mines from Jeongjeon and Ocheon areas in Boryoung, Chungnam. They are mined asbestos for past several decades. Host rocks are serpentinites for Jeongjeon mine and dolomites for Ocheon mine. Asbestos samples and their host rocks are collected from the field trips and examined with microscopes and FESEM, and analysed with XRD and EDX to confirm for the type and/or compositions of the minerals. The asbestos occur as layers, cracks and fractures assummed as a pathway of the hydrothermal water, but show different characteristics. The serpentinites from the Jeongjeon mine contain chrysotile, tremolite and actinolite asbestos. Non-asbestos minerals including tremolite and actinolite were also found. The chrysotiles occur as a cross fiber or slip fiber at veins and along cracks of several mm to cm thickness. Tremolite and actinolite asbestos occur along cracks and fractures of several cm to ten cm thickness. It suggests that the asbestos from Jeongjeon area were formed by the reactions between serpentinite and hydrothermal water. The dolomites of the Ocheon mine only contain tremolite and actinolite asbestos. The asbestos occur along layers, cracks and fractures, suggestive of asbestos from Ocheon area formed by the reactions between dolomite and hydrothermal waters influxed along layers, cracks and fractures. Overall results suggest that two asbestos mines showing different host rocks are located in a Boryoung area. They show a different type of asbestos minerals, reflecting variety of petrogeneses.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.877-883
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• 2003

Multi-degradable master hatch (M/B) was prepared and 0.05 mm polyethylene (PP) food packaging films containing 0, 10, and 20% M/B were manufactured by inflation film processing. The films were exposed to UV radiation, fungi, and heat in order to observe their photolysis, biodegradability, and thermal degradability, respectively. While pure PP film maintained more than 70% of its original elongation after 8 weeks of UV radiation, an almost perfect loss in the elongation of PP film containing 20% M/B was observed. Significant decreases in elongation of PP films by heat treatment $(68{\pm}2^{\circ}C)$ were also found in samples containing the multi-degradable M/B. By observing changes in film surface after the inoculation of fungi using scanning electron microscopy (SEM), the biodegradability of plastic film could be accelerated with the addition of multi-degradable M/B. The results of the mulching test in yard showed that adding multi-degradable M/B can effectively degrade plastic films in natural environmental conditions without interrupting the growth of plants.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.377-388
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• 2008

The aim of the present study is to compare the corrosion tendency using two kinds of NiTi files in the various environmental conditions through the visual examination and electrochemical analysis. ProTaper Universal S2, 21 mm (Dentsply Maillefer, Ballaigues, Switzerland) and Hero 642, 0.06 tapers, size 25, 21 mm (Micromega, Besancon, France) rotary instruments were tested. The instruments were randomly divided into eighteen groups (n = 5) by the immersion temperature, the type of solution, the brand of NiTi rotary instrument and the presence of mechanical loading. Each file was examined at various magnifications using Scanning Electron Microscope (JEOL, Akishima, Tokyo, Japan) equipped with energy dispersive X-ray microanalysis (EDX). EDX was used to determine the components of the endodontic file alloy in corroded and noncorroded areas. The corrosion resistance of unused and used NiTi files after repeated uses in the human teeth was evaluated electrochemically by potentiodynamic polarization test using a potentiostat (Applied Corrosion Monitoring, Cark-in-Cartmel, UK). Solution temperature and chloride ion concentration may affect on passivity of NiTi files. Under the conditions of this in vitro study, the corrosion resistance is slightly increased after clinical use.

• Proceedings of the KSEEG Conference
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• 2002.10a
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• pp.153-169
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• 2002

국내 대리석류 석재자원은 지질시대 및 지구조별로 선캠브리아기의 경기육괴와 영남육괴, 시대미상의 옥천대 남서부, 캠브리아-오오도비스기의 옥천대 북동부, 그리고 일부 기타시대의 옥천대 북동부 등으로 분류될 수 있다. 전자는 변성퇴적암류내에 협재된 결정질 석회암, 화강암질 편마암내 포획된 결정질 석회암 등s으로 경기육괴의 포천, 김포, 온수리, 목계와 신림도폭 그리고 영남육괴의 춘양, 현동, 울진, 중평동, 장기리와 장계도폭 등이 해당된다. 시대미상암류는 옥천대 남서부로서 목계, 충주, 괴산, 강경, 남원과 송정도폭, 그리고 캠브리아기는 풍촌석회암으로 임계, 호명, 서벽리도폭 등기 해당된다. 오오도비스기는 정선석회암이 분포하는 석병산, 평창, 정선과 임계도폭, 화천리층이 분포하는 문경도폭, 그리고 황강리도폭 등디 해당한다 기타시대는 시대미상의 각력질 석회암과 상부석탄기의 홍점층군내 협재하는 결정질 석회암으로, 이들은 각각 정선도폭과 석병산도폭에 위치한다. 선캠브리아기, 시대미상, 캠브리아기 및 오오도비스기 대리석류의 물성 중에서 흡수율과 공극율은 선캠브리아기, 오오도비스기, 시대미상과 캠브리아기의 순으로 점차 감소한다. 이들의 공극율은 비중에 대하여 대체로 불규칙하며, 흡수율은 공극율에 대하여 거의가 뚜렷한 정의 상관관계를 이룬다. 압축강도는 공극율에 대하여 다소 불규칙한, 그리고 인장강도에 대하여 정의 상관관계를 이룬다. 그리고 마모경도는 압축강도와 인장강도에 대하여 대체로 뚜렷한 정의 경향을 각각 보인다. 이들 대리석류는 선캠브리아기 중경암-경암, 시대미상 중경암-경암, 캠브리아기 거의가 중경암-경암, 그리고 오오도비스기는 경암에 각각 해당한다.하고 구현 단계의 문제점들과 해결책을 기술한다. 다 솔레노이드방식 감압건조장치로 건조한 표고버섯으로 품위에 대한 유의성 검증결과, 표고버섯의 경우 온도별로는 색택과 복원률, 건조실 내부 압력별로는 수축률, 복원률에서 유의차가 있는 것으로 나타났다. 라. 본 연구에서 구명된 감압건조특성을 기초로 하여 배치식 감압건조기를 설계 제작에 활용하고자 한다.ational banks. Several financial interchange standards which are involved in B2B business of e-procurement, e-placement, e-payment are also investigated.. monocytogenes, E. coli 및 S. enteritidis에 대한 키토산의 최소저해농도는 각각 0.1461 mg/mL, 0.2419 mg/mL, 0.0980 mg/mL 및 0.0490 mg/mL로 측정되었다. 또한 2%(v/v) 초산 자체의 최소저해농도를 측정한 결과, B. cereus, L. mosocytogenes, E. eoli에 대해서는 control과 비교시 유의적인 항균효과는 나타나지 않았다. 반면에 S. enteritidis의 경우는 배양시간 4시간까지는 항균활성을 나타내었지만, 8시간 이후부터는 S. enteritidis의 성장이 control 보다 높아져 배양시간 20시간에서는 control 보다 약 2배 이상 균주의 성장을 촉진시켰다.차에 따른 개별화 학습을 가능하게 할 뿐만 아니라 능동적인 참여를 유도하여 학습효율을 높일 수 있을 것으로 기대된다.향은 패션마케팅의 정의와 적용범위를 축소시킬 수 있는 위험을 내재한

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.333-340
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• 1997

An analytical method was developed to determine residues of haloxyfop-R and its methyl ester in soils and soybeans using gas-liquid chromatography (GLC) with electron capture detector (ECD). Soil or soybean sample was acidified and extracted with acetone. The extract was then subjected to ion-associated partition to individually separate haloxyfop-R and the neutral methyl ester. One phase containing haloxyfop-R was methylated with $BF_3$/methanol, partitioned to n-hexane and analyzed by GLC/ECD. The other phase containing the methyl ester was further purified by Florisil column chromatography prior to GLC determination. No cross contamination was found between two phases containing each of the acid and methyl ester, thus two compounds can be separately determined as the identical haloxyfop-R-methyl. Overall recoveries of haloxyfop-R from fortified samples averaged 88.2${\pm}$3.9% (n=12) and 88.3${\pm}$4.0% (n=6) for soils and soybeans respectively, and those of haloxyfop-R-methyl showed mean values of 89.2${\pm}$4.0% (n=12) and 85.6${\pm}$5.6% (n=6). Detection limits of both haloxyfop-R and its methyl esterwere 0.005㎎/㎏ and 0.01㎎/㎏ for soil and soybean samples respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.415-424
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• 2019

In this paper, a minimum rotation radius was designed and fabricated to overcome the threshold so that elderly or disabled people who have difficulty moving can move and transfer safely and conveniently in a narrow room. In the indoor environment, where the sedentary culture develops, this study aimed to provide convenience for passengers with fracture diseases, geriatric diseases, and other knee and waist diseases. First, links, seats, armrests, covers, motors, batteries, chargers, controllers, etc. were attached to the frame so that they could be moved and lifted indoors. The product design and structure were designed considering the user's environment and physical characteristics, and IoT functions were added. A driving experiment was performed to confirm the operating performance of the manufactured indoor moving and lifting wheelchair. The performance tests, such as continuous running time, turning radius, maximum actuator load, maximum lift height, sound pressure level, minimum sensing distance of the driving aid sensor, interworking of server and app programs, device compatibility, and duty cycle error rate, were performed. As a result of the test, the built-in wheelchair could achieve the performance test target of each item and operate successfully.