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The Development of Height Adjustable Steel Manhole cover (높이조절이 가능한 강재 맨홀뚜껑의 개발)

  • Park, Woo-Cheul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.6
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    • pp.581-586
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    • 2018
  • Cast iron manhole lids cause environmental pollution during the manufacturing process, and the work environment is very poor. In addition, if the height of the manhole cover does not match the height of the road surface, it causes considerable inconvenience and safety problems. This study proposes a height - adjustable steel manhole cover that can replace cast iron manhole covers and easily match the road surface with the upper surface of the manhole cover. Structural analysis was performed to grasp the design variable of the structure of the manhole cover, satisfying the required quality performance. To fabricate a manhole cover that satisfies the required load capacity, the optimal design for the U-shaped reinforcement structure was made. The cylindrical shape of the height adjustment part and the low frame were formed by bending the steel sheet into a circular shape and then welding. Reinforcing bars were also made by bending a steel plate. The height adjustment groove was machined by a CNC milling machine. Four prototypes were fabricated and a load bearing test was carried out, and new manhole cover was made reflecting results of the test. In the load bearing test, there was no breakage of the welded part, and deformation occurred mainly at the contact area between the groove and gusset plate. Deformation of 1 to 2.7mm occurred due to a load of 450kN. On the other hand, after removing the load, there was almost no residual deformation, and the load bearing evaluation was judged to be satisfactory because the manhole cover could be disassembled and reassembled.

A Study on the Introduction of Effective Route Exchange System in the VTS Area (해상교통관제해역 내 효과적 경로교환 체계 도입에 관한 연구)

  • Pak, Chae-Hong;Jung, Chang-Hyun;Park, Sung-Hyeon
    • Journal of Navigation and Port Research
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    • v.38 no.3
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    • pp.217-225
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    • 2014
  • The system that covers gathering, integrating, exchanging, presenting and analyzing of information within ships and shores for the safety and security in Marine Environment is known as e-Navigation Policy. Northern Europe has been conducting research and development. It came up into a concept that deals with ship's route information between vessels as well as vessels to shores which is better known as route exchange system. The research showed substantial advantages on navigational safety by exchanging the route information between vessels in vicinity and vessels to shores. Therefore, upon the adaptation of route exchange System as a major function in integrated navigational system, the existing procedures in VTS could be changed for betterment. In this study, it was verified the effectiveness of route exchange system by the adaptation of a recent collision accident occurred in Korean coast and suggested that route exchange system which would be carried out by the discretion of VTS center in VTS area. Finally, it proposed the new functions for outstanding services and procedures of integrating traffic organization services on coastal VTS for an effective route exchange system in Korean coastal area.

A Molecular Dynamics Simulation Study of Hydroxyls in Dioctahedral Phyllosilicates (분자동역학 시뮬레이션을 이용한 이팔면체 점토광물 수산기 연구)

  • Son, Sangbo;Kwon, Kideok D.
    • Journal of the Mineralogical Society of Korea
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    • v.29 no.4
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    • pp.209-220
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    • 2016
  • Clay minerals are a major player to determine geochemical cycles of trace metals and carbon in the critical zone which covers the atmosphere down to groundwater aquifers. Molecular dynamics (MD) simulations can examine the Earth materials at an atomic level and, therefore, provide detailed fundamental-level insights related to physicochemical properties of clay minerals. In the current study, we have applied classical MD simulations with clayFF force field to dioctahedral clay minerals (i.e., gibbsite, kaolinite, and pyrophyllite) to analyze and compare structural parameters (lattice parameter, atomic pair distance) with experiments. We further calculated vibrational power spectra for the hydroxyls of the minerals by using the MD simulations results. The MD simulations predicted lattice parameters and interatomic distances respectively deviated less than 0.1~3.7% and 5% from the experimental results. The stretching vibrational wavenumber of the hydroxyl groups were calculated $200-300cm^{-1}$ higher than experiment. However, the trends in the frequencies among different surface hydroxyl groups of each mineral was consistent with experimental results. The angle formed by the surface hydroxyl group with the (001) plane and hydrogen bond distances of the surface hydroxyls were consistent with experimental result trends. The inner hydroxyls, however, showed results somewhat deviated from reported data in the literature. These results indicate that molecular dynamics simulations with clayFF can be a useful method in elucidating the roles of surface hydroxyl groups in the adsorption of metal ions to clay minerals.

Research on the manual development for activating teaching consulting in mathematics (수업컨설팅 활성화를 위한 매뉴얼 개발 - 수학 교과를 중심으로 -)

  • Choe, Seung-Hyun;Hwang, Hye Jeang;Nam, Geum Cheon
    • Journal of the Korean School Mathematics Society
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    • v.16 no.1
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    • pp.1-29
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    • 2013
  • The main goal of the research is to develop instructional consulting manual to help math teachers improve classroom teaching. Improving the quality of teaching in schools is stressed as a central focus of meaningful classroom instruction and high quality education. In this research, teaching consulting was defined as an activity that covers reflection process oriented towards formative assessment and continuing professional development. Within this context, subject-specific teaching consulting and teaching professionalism with focus on PCK was reviewed. Further, the questionnaire survey was conducted to investigate the current situation of teaching consulting and teachers' needs for consulting. And also, specific examples of subject-specific consulting based on our previous consulting experiences in math classes were shown. Alternative ways to improve subject teaching were derived through the conferences where consultants and consultees analyze video-taped lessons conducted by the consultees. By those results, a manual for invigorating teaching consulting was developed. The contents of the manual consists of setting conditions of teaching consulting and its implementation in the classroom teaching. The first part of the manual contains steps to establish teaching consulting system, the qualification and role of the consultant, system evaluation, etc. The second part of the manual presents the pre-preparation, prescription and implementation and follow-up management steps. Each part of the manual provides consultants with specific guidelines for each step. Finally, recommendations for making policy related to ways to invigorate teaching consulting was suggested. It is expected that specific examples and cases of subject-specific teaching consulting presented in this research will be used to narrow the gap between theory and practice of teaching consulting, and to help math, science and English teachers develop teaching professionalism.

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A Study on the Land Surface Emissivity (LSE) Distribution of Mid-wavelength Infrared (MWIR) over the Korean Peninsula (한반도 중파장적외선 지표 복사율 분포 연구)

  • Sun, Jongsun;Park, Wook;Won, Joong-sun
    • Korean Journal of Remote Sensing
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    • v.32 no.5
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    • pp.423-434
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    • 2016
  • Surface emissivity and its background values according to each sensor are mandatorily necessary for Mid-Wavelength Infrared (MWIR) remote sensing to retrieve surface temperature and temporal variation. This study presents the methods and results of Land Surface Emissivity (LSE) of the MWIR according to land cover over the Korean Peninsula. The MWIR emissivity was estimated by applying the Temperature Independent Spectral Indices (TISI) method to the Visible Infrared Imaging Radiometer Suite (VIIRS) band 4 Day/Night images ($3.74{\mu}m$ in center wavelength). The obtained values were classified according to land-cover types, and the obtained emissivity was then compared with those calculated from a standard Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) spectral library. The annual means of MWIR emissivity of Deciduous Broadleaf Forest (0.958) and Mixed Forest (0.935) are higher than those of Croplands (0.925) and Natural Vegetation Mosaics (0.935) by about 2-3%. The annual mean of Urban area is the lowest (0.914) with an annual variation of about 2% which is by larger than those (1%) of other land-covers. The TISI and VIIRS based emissivity is slightly lower than the ASTER spectral library by about 2-3% supposedly due to various reasons such as lack of land cover homogeneity. The results will be used to understand the MWIR emissivity properties of the Korean Peninsula and to examine the seasonal and other environmental changes using MWIR images.

WRF-Based Short-Range Forecast System of the Korea Air Force : Verification of Prediction Skill in 2009 Summer (WRF 기반 공군 단기 수치 예보 시스템 : 2009년 하계 모의 성능 검증)

  • Byun, Ui-Yong;Hong, Song-You;Shin, Hyeyum;Lee, Ji-Woo;Song, Jae-Ik;Hahm, Sook-Jung;Kim, Jwa-Kyum;Kim, Hyung-Woo;Kim, Jong-Suk
    • Atmosphere
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    • v.21 no.2
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    • pp.197-208
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    • 2011
  • The objective of this study is to describe the short-range forecast system of the Korea Air Force (KAF) and to verificate its performace in 2009 summer. The KAF weather prediction model system, based on the Weather Research and Forecasting (WRF) model (i.e., the KAF-WRF), is configured with a parent domain overs East Asia and two nested domains with the finest horizontal grid size of 2 km. Each domain covers the Korean peninsula and South Korea, respectively. The model is integrated for 84 hour 4 times a day with the initial and boundary conditions from National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) data. A quantitative verification system is constructed for the East Asia and Korean peninsula domains. Verification variables for the East Asia domain are 500 hPa temperature, wind and geopotential height fields, and the skill score is calculated using the difference between the analysis data from the NCEP GFS model and the forecast data of the KAF-WRF model results. Accuracy of precipitation for the Korean penisula domain is examined using the contingency table that is made of the KAF-WRF model results and the KMA (Korea Meteorological Administraion) AWS (Automatic Weather Station) data. Using the verification system, the operational model and parallel model with updated version of the WRF model and improved physics process are quantitatively evaluated for the 2009 summer. Over the East Aisa region, the parallel experimental model shows the better performance than the operation model. Errors of the experimental model in 500 hPa geopotential height near the Tibetan plateau are smaller than errors in the operational model. Over the Korean peninsula, verification of precipitation prediction skills shows that the performance of the operational model is better than that of the experimental one in simulating light precipitation. However, performance of experimental one is generally better than that of operational one, in prediction.

Synthesis and Crystallization of Amorphous Calcium Carbonate by Gas-Liquid Reaction of System Ca($OH_2 O$)-$H_2$-$CO_2$ (Ca($OH_2$)-$H_2 O$-$CO_2$계의 기액반응으로부터 비정질 탄산칼슘의 합성 및 결정화)

  • Im, Jae-Seok;Kim, Ga-Yeon;Im, Goeng
    • The Journal of Engineering Research
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    • v.5 no.1
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    • pp.73-87
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    • 2004
  • The synthesis and crystallization of amorphous calcium carbonate($CaCO_3$.$nH_2 O$) obtained from gas-liquid reaction between aqueous solution of calcium hydroxide and carbon dioxide at 15~$50^{\circ}C$ are investigated by electrical conductometry, XRD and TEM. The results are as follows: The initial reaction products prior to the formation of precipitated calcium carbonate is amorphous calcium carbonate. The electrical conductivity values in the slurry are decreased during the formation of amorphous calcium carbonate which covers particle surface of calcium hydroxide and retard the dissolution of calcium hydroxide into the solution. that amorphous calcium carbonate is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. While amorphous calcium carbonate crystallizes into chain-like calcite, the conductivity values are recovered rapidly and the apparent viscosity of slurry containing higher concentration of calcium hydroxide increase. At below pH 9.5, chain-like calcite separates into individual particles to form precipitated calcium carbonate. The formation and synthetic temperature range of amorphous calcium carbonate is most suitable a primary decreasing step(a-step) at $15^{\circ}C$ in the electrical conductometry.

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Evaluation of Forest Watershed Hydro-Ecology using Measured Data and RHESSys Model -For the Seolmacheon Catchment- (관측자료와 RHESSys 모형을 이용한 산림유역의 생태수문 적용성 평가 -설마천유역을 대상으로-)

  • Shin, Hyung Jin;Park, Min Ji;Kim, Seong Joon
    • Journal of Korea Water Resources Association
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    • v.45 no.12
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    • pp.1293-1307
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    • 2012
  • This study is to evaluate the RHESSys (Regional Hydro-Ecological Simulation System) simulated streamflow (Q), evapotranspiration (ET), soil moisture (SM), gross primary productivity (GPP) and photosynthetic productivity (PSNnet) with the measured data. The RHESSys is a hydro-ecological model designed to simulate integrated water, carbon, and nutrient cycling and transport over spatially variable terrain. A 8.5 $km^2$ Seolma-cheon catchment located in the northwest of South Korea was adopted. The catchment covers 90.0% forest and the dominant soil is sandy loam. The model was calibrated with 2 years (2007-2008) daily Q at the watershed outlet and MODIS (Moderate Resolution Imaging Spectroradiometer) GPP, PSNnet and 3 year (2007~2009) daily ET data measured at flux tower using the eddy-covariance technique. The coefficient of determination ($R^2$) and the Nash-Sutcliffe model efficiency (ME) for Q were 0.74 and 0.63, and the average $R^2$ for ET and GPP were 0.54 and 0.93 respectively. The model was validated with 1 year (2009) Q and GPP. The $R^2$ and the ME for Q were 0.92 and 0.84, the $R^2$ for GPP were 0.93.

A Clinicopathologic Analysis of Neck Masses (경부 종괴의 임상 및 병리학적 고찰)

  • Km Jeong-Ho;Oh Sang-Hoon;Kim Sang-Hyo
    • Korean Journal of Head & Neck Oncology
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    • v.13 no.1
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    • pp.51-57
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    • 1997
  • A mass appearing in the anterior or lateral side of neck often can be a diagnostic challenge. Differential diagnosis of the neck mass covers a broad spectrum of diseases and the proper evaluation and management of a neck mass requires an impressive amount of anatomic and pathologic information. Because improper diagnosis and management may convert a potentially curable malignant metastasis into incurable disease, a differential diagnosis must be considered in all patients who present with a neck mass. Authors reviewed 2,148 cases of neck mass who were diagnosed by surgical resection, biopsy or aspiration during the period between October 1982 to December 1993, excluding those with thyroid and parathyroid disease. The evaluated characteristics were age, sex, site of lesion, and pathologic diagnosis. The results were as follows: Of 2,148 cases of neck mass, the overall ratio of benign to malignant tumor was 3 : 1. In 1,603 cases of benign mass lesion, the most common disease was lymphadenitis(non-specific and tuberculosis) showing 53% incidence, the second was salivary gland tumor(13%), and the third was congenital lesion(12%). The minor problems such as lipoma and sebaceous cyst were 21 %. In the age distribution of benign lesion, tuberculous lymphadenitis showed peak incidence in second decade, non-specific lymphadenitis was main disease of childhood, salivary gland tumor was peak in fourth decade, and most of congenital lesions were diagnosed at the age below 15. In 545 malignant tumors, the most common lesion was metastatic cancer to cervical lymph nodes yielding 71 % incidence(head and neck primary 52%, infraclavicular primary 42%, unknown primary 5%), the second common disease was lymphoma(19%), and the third was salivary gland cancer(9%). In the age incidence of malignant tumor, 60% of them developed in the fifth and sixth decade, head and neck primary was more common in the fifth decade than sixth, however lymphoma showed higher incidence in sixth decade. In the analysis of mass location according to lymph node level grouping(I - V), lymphadenitis developed mostly in level V nodes, the next common occurring site was level IV in tuberculous lymphadenitis and level II in non-specific lymphadenitis. The majority of metastatic cancers were found in level IV and III, and common occurring site of lymphoma was in level II and IV. Pathologic diagnosis of neck masses were made by fine needle aspiration cytology 80 cases, incisional biopsy 533 cases, excisional surgery 1,399 cases, and neck dissection 116 cases. For the proper management of neck mass, a proper diagnostic modality should be selected from imaging techniques, cytology, biopsy or neck dissection, with the consideration of patient's age, history and clinical findings. The scapel biopsy could be used freely in the inflammatory disease or inoperable metastatic cancer, but it should be reserved in the curable metastatic cancer or clinically possible malignancy.

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Development of Estimation Model of Trip Generation Model and Trip Distribution Model Reflecting Coefficient of Accessibility (접근성 변수를 반영한 통행발생 및 통행분포모형 개발)

  • Jeon, Yong-Hyun;Rho, Jeong-Hyun;Jang, Jun-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.576-584
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    • 2017
  • Traffic demand prediction result is a primary factor for decision making such as the traffic planning and operation. The existing traffic demand prediction 4-step model only covers the trip between the origin and the destination, and not the demand followed by the accessibility improvement, due to the characteristic of this model. Therefore, the purpose of this research is to improve the limitations of the existing model by developing the inter-city trip generation and trip distribution model with more accessibility. After calculating of the trip generation and trip distribution model with more accessibility, the sign of the accessibility coefficient was positive. Commuting was the most insensitive indicator, affected by external factors among the other trip purposes. The leisure trip was the most sensitive, affected by the trip fee. According to the result of comparison with each of estimated model and observational data, it was certain that the reliability and assumption of the model have been improved by discovering the reduced weighted average error rate, Root Mean Square Error (RMSE) and total error through the model with more accessibility compared with the existing one.