• 한국산학기술학회논문지
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• 제7권5호
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• pp.830-836
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• 2006

본 논문에서는 기존의 PID 제어기와 퍼지 제어기의 특성을 공통으로 갖는 새로운 형태의 신경회로망 기반 자동 동조 뉴로-퍼지 PID제어기를 제안하였다. 제안된 제어기는 퍼지의 선형성을 이용하여 퍼지 PID 제어기의 퍼지 연산부를 간략화 시키고 일반 PID 제어기와 유사한 입출력 특성을 갖도록 하였으며 비선형 성분 보상을 위하여 제어기 출력에 가장 큰 영향을 미치는 출력측 스케일 계수를 단일 신경 회로망 구조로 변경하고 PID 제어기 구조를 유지하게 하였다. 또한 단일 신경 회로망 구조를 이용함으로써 신경회로망의 초기 연결강도와 계산량에 대한 문제점을 해결하고 오차의 부호 정보에 따라 학습계수를 변화시키는 가변 학습계수 역전파 알고리즘을 사용하여 오버 슈트가 작으면서도 빠른 수렴 속도를 갖도록 하였다. 제안된 제어기를 비선형성이 강한 시스템으로 알려진 자기 부양(magnetic levitation) 시스템에 실제 적용하여 본 논문에서 제안한 제어기의 우수한 성능을 확인하였다.

• 한국환경보건학회지
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• 제47권5호
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• pp.454-461
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• 2021

Background: Fish and fishery products (FFPs) unintentionally contaminated with various environmental pollutants are major exposure pathways for humans. To protect human health from the consumption of contaminated FFPs, it is essential to develop a systematic tool for evaluating exposure and risks. Objectives: To regularly, accurately, and quickly evaluate adverse health outcomes due to FFPs contamination, we developed an automated dietary exposure and risk assessment system called HERA (the Human Exposure and Risk Assessment system for chemicals in FFPs). The aim of this study was to develop an overall architecture design and demonstrate the major features of the HERA system. Methods: For the HERA system, the architecture framework consisted of multi-layer stacks from infrastructure to fish exposure and risk assessment layers. To compile different contamination levels and types of seafood consumption datasets, the data models were designed for the classification codes of FFP items, contaminants, and health-based guidance values (HBGVs). A systematic data pipeline for summarizing exposure factors was constructed through down-scaling and preprocessing the 24-hour dietary recalls raw dataset from the Korea National Health and Nutrition Examination Survey (KNAHES). Results: According to the designed data models for the classification codes, we standardized 167 seafood items and 2,741 contaminants. Subsequently, we implemented two major functional workflows: 1) preparation and 2) main process. The HERA system was developed to enable risk assessors to accumulate the concentration databases sustainably and estimate exposure levels for several populations linked to seafood consumption data in KNAHES in a user-friendly manner and in a local PC environment. Conclusions: The HERA system will support policy-makers in making risk management decisions based on a nation-wide risk assessment for FFPs.

• 대한조선학회논문집
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• 제55권6호
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• pp.490-496
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• 2018

The consistency of the initially designed waves in the domain is essential for accurate calculation of the added resistance in waves through CFD. In particular, unwanted reflected waves at domain boundaries can cause incorrect numerical solutions due to the superposition with initially designed waves. Euler Overlay Method(EOM) is one of the methods for reducing wave reflections by adding an additional source term to momentum and phase conservation equations, respectively. In this study, we apply the Euler Overlay Method(EOM) to the open-source CFD library, OpenFOAM(R), to simulate the accurate free-surface waves in the domain and the parametric study is performed for efficient implementation of Euler Overlay Method(EOM). Considering that the damping efficiency depends on the selection of the overlay parameter in the added source terms, the size of overlay zone and the wave steepness, the influences of these factors are tested through the wave elevation measured at constant time intervals in the 2D numerical wave tank. Through this process, guidelines for selection of optimal overlay parameter and overlay zone size that can be applied according to the scaling law are finally presented.

• 한국융합학회논문지
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• 제12권2호
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• pp.129-134
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• 2021

본 연구는 치과교정치료 환자의 구강건강관련 삶의 질과 구강보건행동 변화를 알아보기 위해 교정치료를 완료한 성인 300명을 대상으로 설문조사를 시행하였다. 수집된 자료의 분석은 spss22.0프로그램을 이용하여 분석 하였다. 교정치료전은 사회적인 요인이(4.68) 관련 삶의 질 점수가 가장 낮게 나타났고, 교정치료 후에는 사회적 요인 관련 삶의 질이 3.72점 높아져 가장 높은 증가를 나타냈다. 구강보건행동변화는 정기적인 스켈링이 교정 전에 비해 교정 후가 1.28점 더 증가하였다. 교정치료를 통해 구강건강 삶의 질과 구강보건행동이 변화 된 바 치과의 전문인력은 환자 개개인별 맞춤형 구강보건교육을 통해 적절한 관리를 기울일 필요가 있으며 교정치료 환자의 삶의 질을 향상시키기 위해 적절한 접근법 개발이 필요하다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권spc호
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• pp.92-98
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• 2022

Although various methods have been proposed to assess groundwater vulnerability, most of the models merely consider the mobility of contaminants (i.e., intrinsic vulnerability), and the attenuation capacity of vadose zone is often neglected. This study proposed an evaluation model for the attenuation capacity of vadose zone to supplement the limitations of the existing index method models for assessing groundwater vulnerability. The evaluation equation for quantifying the attenuation capacity was developed from the combined linear regression and weighted scaling methods based on the lab-scale experiments using various vadose zone soils having different physical and biogeochemical properties. The proposed semi-quantifying model is expected to effectively assess the attenuation capacity of vadose zone by identifying the main influencing factors as input parameters together with proper weights derived from the coefficients of the regression results. The subsequent scoring and grading system has great versatility while securing the objectivity by effectively incorporating the experimental results.

• 한국수산과학회지
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• 제55권2호
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• pp.154-170
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• 2022

The zooplankton composition, abundance, community structure, and species diversity in the major commercial fishery species spawning grounds in the southern coast of Korea were investigated in this study. A total of 80 taxa were sampled, with the mean abundance range of 5,612-11,720 ind. m^-3 and the mean biomass range of 41.6-1,086.8 mg m^-3. The dominant species were Paracalanus copepodites, Paracalanus parvus s. l., Oithona copepodites, Paracalanus nauplii, Noctiluca scintillans, Oithona similis, and Ditrichocorycaeus affinis. The species diversity indices were highest in August, suggesting that diversity is influenced by neritic and oceanic warm-water species. A cluster analysis with non-metric multidimensional scaling (nMDS) revealed three groups of zooplankton communities. The April and May samples clustered into Group A, having the highest mean total zooplankton abundance and lowest species diversity, consisting mainly of temperate species located in the middle region of the southern coast of Korea. Cluster Group B was from the early summer season (June) and contained the highest species diversity with some oceanic and neritic zooplankton species. Cluster Group C from the summer season (July and August) mainly comprised P. parvus s. l. and O. similis. The redundancy analysis (RDA) indicated that abundance is positively correlated with salinity, and chlorophyll-a concentrations.

• 한국물환경학회지
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• 제39권2호
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• pp.181-193
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• 2023

Distribution changes in microalgae communities were studied in the Nakdonggang River at two sampling stations (St.1 Gyeongcheongyo Bridge (GB) and St.2 Daedong Wharf (DW)) at monthly intervals from January 2021 to November 2021. A total of 83 taxa included 82 species, 1 forma, belonging to 49 genera, 32 families, 21 orders, and 8 classes. The most important groups were Bacillariophyta and Chlorophyta. The number of species ranged from 5 to 24 in GB, and from 9 to 21 taxa in DW. The contribution of Bacillariophyta to the total species richness was the highest during all survey periods, and Chlorophyta yielded the next highest value in the study area. The dominant taxa were Aulacoseira ambigua, A. ambigua f. japonica, and Ulnaria acus in this study. Cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on Bray- Curtis similarity identified 4 major groups, which corresponded to microalgae assemblages and their characteristic species. Correlation was analyzed through the CCA analysis. It was found that there was a correlation between the microalgae and environmental factors. It was revealed that the divided groups were distinguished because of the differences by the survey period. Therefore, seasonal change was judged as a major factor affecting the distribution of microalgae communities.

• Earthquakes and Structures
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• 제24권4호
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• pp.289-301
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• 2023

Developing a competent soil-bridge interaction model for the seismic analysis of piled foundation bridges is of utmost importance for investigating the seismic response and assessing fragility of these lifeline structures. To this end, ground motion histories are deemed necessary at various depths along the piles supporting the bridge. This may be effectively accomplished through time history analysis of a free-field standalone soil column extending from bedrock level to ground surface subjected to an input bedrock motion at its base. A one-dimensional site/ground response analysis (vide one-directional shear wave propagation through the soil column) is hence conducted in the present research accounting for the nonlinear hysteretic behavior of the soil stratum encompassing the bridge piled foundation. Two homogeneous soil profiles atop of bedrock have been considered for comparison purposes, namely, loose and dense sand. Analysis of the standalone soil column has been performed under a set of ten selected actual bedrock ground motions adopting a nonlinear time domain approach in an incremental dynamic analysis framework. Amplified retrieved PGA and maximum soil shear strains have been generally observed at various depths of the soil column when moving away from bedrock towards ground surface especially at large hazards associated with high (input) PGA values assigned at bedrock. This has been accompanied, however, by some attenuation of the amplified PGA values at shallower depths and at ground surface especially for the loose sand soil and particularly for cases with higher seismic hazards associated with large scaling factors of bedrock records.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.142-142
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• 2023

Humans inevitably and continuously produce wastewater in daily life worldwide. To decrease the degradation of river water bodies and aquatic ecosystem therein, humans have built systems at different scales to collect, drain, and treat household-produced wastewater. Particularly, municipal wastewater treatment plants (WWTPs) with centralized controls have played a key role in reducing loads of nutrients in domestic wastewater for the last few decades. Notwithstanding such contributions, impaired rivers regarding water quality and habitat integrity still exist at the whole river basin scale. It is highly attributable to the absence of dilution capacity of receiving streams and/or the accumulation of the pollutant loads along flow paths. To improve the perspective for individual WWTPs assessment, the first crucial step is to achieve systematic understanding on spatial distribution characteristics of all WWTPs together in a given river basin. By taking the initiative, our former study showed spatial hierarchical distributions of WWTPs in three large urbanized river basins in Germany. In this study, we uncover how municipal WWTPs in the contiguous United States are distributed along river networks in a give river basin. The extended spatial scope allows to deal with wide ranges in geomorphological attributes, hydro-climatic conditions, and socio-economic status. Furthermore, we identify the relation of the findings with multiple factors related to human activities, such as the spatial distribution of human settlements, the degree of economy development, and the fraction of communities served by WWTPs. Generalizable patterns found in this study are expected to contribute to establishing viable management plans for recent water-environmental challenges caused by WWTP-discharges to river water bodies.

• 한국심리학회지 : 문화 및 사회문제
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• 제25권3호
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• pp.203-229
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• 2019

본 연구의 목적은 한국사회의 남성들의 남성규범을 구성하는 요인들을 확인하고, 그 개념적 구조를 파악하는 것이다. 남성성 개념의 이론적 근거에 따라 사회문화적으로 형성된 남성성 역할 기준에 순응하고자 하는 정도를 남성성으로 정의하였다. 이를 위하여 개념도 방법을 사용하여 20명의 남성참가자들을 대상으로 한국사회에서 남자답다는 것은 무엇인지 심층면접을 실시하였다. 이후 남성규범과 관련한 핵심문장을 추출한 후 참가자에게 추출된 55개의 핵심문장에 대해 분류하고 그 중요도를 평정하게 하였다. 참가자들이 분류한 문항에 대해서는 다차원척도법과 군집분석을 실시하여 남성규범에 대한 개념적 구조를 탐색하였다. 그 결과 나타난 이차원의 축을 한국사회 문화에 대한 이론과 내용을 바탕으로 각각 집단관계 영역 대 개인내적 영역, 사회적영역과 위계성 추구 대 온정적 관계 추구로 명명하였다. 또한 하위 군집으로는 부양자, 리더쉽, 정서억제, 직무능력과 조직사회적응, 기대외는 남성적 능력, 힘과 통제의 6가지 군집이 나타났다. 각 군집의 특징과 의미를 한국사회문화 맥락에 따라 해석하고 연구의 의의, 제안점 및 추후 연구에 대한 제언 등을 논의하였다.