• Water Engineering Research
• /
• 제4권1호
• /
• pp.19-30
• /
• 2003

TMDL development and implementation have great potential fur use in efforts to improve water quality management, but the TMDL approach still has several difficulties to overcome in terms of cost, time requirements, and suitable methodologies. A well-defined prioritization approach for identifying watersheds of concern among several tar-get locations that would benefit from TMDL development and implementation, based on a simple screening approach, could be a major step in solving some of these difficulties. Therefore, a web-based decision support system (DSS) was developed to help identify areas within watersheds that might be priority areas for TMDL development. The DSS includes a graphical user interface based on the HTML protocol, hydrological models, databases, and geographic information system (GIS) capabilities. The DSS has a hydrological model that can estimate non-point source pollution loading based on over 30 years of daily direct runoff using the curve number method and pollutant event mean concentration data. The DSS provides comprehensive output analysis tools using charts and tables, and also provides probability analysis and best management practice cost estimation. In conclusion, the DSS is a simple, affordable tool for the preliminary study of TMDL development via the Internet, and the DSS web site can also be used as an information web server for education related to TMDL.

• 대한불안의학회지
• /
• 제6권1호
• /
• pp.31-36
• /
• 2010

Objective : Mismatch negativity (MMN) provides an electrophysiological index of an involuntary attention switching process. This study investigated MMN anomalies and their relationship to clinical variables in patients with obsessive-compulsive disorder (OCD). Methods : Study participants were 29 OCD patients and 24 normal controls. We used a 128-channel EEG to measure MMN during a passive oddball paradigm. Then we assessed the correlations between MMN amplitudes and clinical measures. Results : The OCD patients exhibited significantly greater MMN amplitude compared to the controls. Also, the right frontal lobe MMN amplitudes correlated significantly to the OCD patients' Yale-Brown Obsessive Compulsive Scale total scores (r=-0.520, p=0.005). Conclusion : These results suggest that MMN anomalies in OCD patients reflect a monitoring circuit dysfunction, raising the possibility that the OCD's pathophysiology includes glutamatergic dysfunction.

• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.760-767
• /
• 2022

This paper introduces alert fatigue and presents methods to measure alert fatigue by using physiological signals. Alert fatigue is a phenomenon that which an individual is constantly exposed to frequent alarms and becomes desensitized to them. Blind spots are one leading cause of struck-by accidents, which is one most common causes of fatal accidents on construction sites. To reduce such accidents, construction equipment is equipped with an alarm system. However, the frequent alarm is inevitable due to the dynamic nature of construction sites and the situation can lead to alert fatigue. This paper introduces alert fatigue and proposes methods to use physiological signals such as electroencephalography, electrodermal activity, and event-related potential for the measurement of alert fatigue. Specifically, this paper presents how raw data from the physiological sensors measuring such signals can be processed to measure alert fatigue. By comparing the processed physiological data to behavioral data, validity of the measurement is tested. Using preliminary experimental results, this paper validates that physiological signals can be useful to measure alert fatigue. The findings of this study can contribute to investigating alert fatigue, which will lead to lowering the struck-by accidents caused by blind spots.

• Communications for Statistical Applications and Methods
• /
• 제30권4호
• /
• pp.389-402
• /
• 2023

Multivariate or clustered failure time data often occur in many medical, epidemiological, and socio-economic studies when survival data are collected from several research centers. If the data are periodically observed as in a longitudinal study, survival times are often subject to various types of interval-censoring, creating multivariate interval-censored data. Then, the event times of interest may be correlated among individuals who come from the same cluster. In this article, we propose a unified linear regression method for analyzing multivariate interval-censored data. We consider a semiparametric multivariate accelerated failure time model as a statistical analysis tool and develop a generalized Buckley-James method to make inferences by imputing interval-censored observations with their conditional mean values. Since the study population consists of several heterogeneous clusters, where the subjects in the same cluster may be related, we propose a generalized estimating equations approach to accommodate potential dependence in clusters. Our simulation results confirm that the proposed estimator is robust to misspecification of working covariance matrix and statistical efficiency can increase when the working covariance structure is close to the truth. The proposed method is applied to the dataset from a diabetic retinopathy study.

• 구강회복응용과학지
• /
• 제27권4호
• /
• pp.449-454
• /
• 2011

근래에 비스포스포테이트(bisphosphonate) 투약의 부작용으로 악골괴사에 관한 보고들이 점차적으로 증가하고 있다. 최근에 보고된 유병율은 대략 0.8% - 12 % 정도이다. 하악은 상악보다 2배 정도 호발하는 것으로 보고되었고 이의 60 - 70 %는 치과진료와 연관성이 거론되었다. 임상적으로 골괴사 현상이 일어나기 전에 건강한 치주조직에 변화가 일어나는데 치유지연 점막궤양, 치아동요와 원인을 알 수 없는 연조직 감염등이 관찰되었다. 치아발거가 치과영역에서 가장 흔한 사전 처치행위로 알려져 있다. 장기적인 비스포스포네이트 투약시 세심한 예방적 치과진료가 이러한 심각한 괴사로 이어지지 않도록 하는데 절대적이다.

• 대한인간공학회지
• /
• 제31권6호
• /
• pp.785-791
• /
• 2012

Objective: The aim of this study was to investigate the correlation between 3D visual fatigue and physiological measures by canonical correlation analysis enabling to categorical correlation. Background: Few studies have been conducted to investigate the physiological mechanism underlying the visual fatigue caused by processing 3D information which may make the cognitive mechanism overloaded. However, even the previous studies lack validation in terms of the correlation between physiological variables and the visual fatigue. Method: 9 Female and 6 male subjects with a mean age of $22.53{\pm}2.55$ voluntarily participated in this experiment. All participants were asked to report how they felt about their health sate at after viewing 3D. In addition, Low & Hybrid measurement test(Event Related Potential, Steady-state Visual Evoked Potential) and for evaluating cognitive fatigue before and after viewing 3D were performed. The physiological signal were measured with subjective fatigue evaluation before and after in watching the 3D content. For this study suggesting categorical correlation, all measures were categorized into three sets such as included Visual Fatigue set(response time, subjective evaluation), Autonomic Nervous System set(PPG frequency, PPG amplitude, HF/LF ratio), Central Nervous System set(ERP amplitude P4, O1, O2, ERP latency P4, O1, O2, SSVEP S/N ratio P4, O1, O2). Then the correlation of three variables sets, canonical correlation analysis was conducted. Results: The results showed a significant correlation between visual fatigue and physiological measures. However, different variables of visual fatigue were highly correlated to respective HF/LF ratio and to ERP latency(O2). Conclusion: Response time was highly correlated to ERP latency(O2) while the subjective evaluation was to HF/LF ratio. Application: This study may provide the most significant variables for the quantitative evaluation of visual fatigue using HF/LF ratio and ERP latency based human performance and subjective fatigue.

• Nuclear Engineering and Technology
• /
• 제46권6호
• /
• pp.803-816
• /
• 2014

Defense-in-depth is a fundamental safety principle for the design and operation of nuclear power plants. Despite its general appeal, defense-in-depth is not without its drawbacks, which include its potential for concealing the occurrence of hazardous states in a system, and more generally rendering the latter more opaque for its operators and managers, thus resulting in safety blind spots. This in turn translates into a shrinking of the time window available for operators to identify an unfolding hazardous condition or situation and intervene to abate it. To prevent this drawback from materializing, we propose in this work a novel safety principle termed "observability-in-depth". We characterize it as the set of provisions technical, operational, and organizational designed to enable the monitoring and identification of emerging hazardous conditions and accident pathogens in real-time and over different time-scales. Observability-in-depth also requires the monitoring of conditions of all safety barriers that implement defense-in-depth; and in so doing it supports sensemaking of identified hazardous conditions, and the understanding of potential accident sequences that might follow (how they can propagate). Observability-in-depth is thus an information-centric principle, and its importance in accident prevention is in the value of the information it provides and actions or safety interventions it spurs. We examine several "event reports" from the U.S. Nuclear Regulatory Commission database, which illustrate specific instances of violation of the observability-in-depth safety principle and the consequences that followed (e.g., unmonitored releases and loss of containments). We also revisit the Three Mile Island accident in light of the proposed principle, and identify causes and consequences of the lack of observability-in-depth related to this accident sequence. We illustrate both the benefits of adopting the observability-in-depth safety principle and the adverse consequences when this principle is violated or not implemented. This work constitutes a first step in the development of the observability-in-depth safety principle, and we hope this effort invites other researchers and safety professionals to further explore and develop this principle and its implementation.

• 한국지진공학회논문집
• /
• 제13권4호
• /
• pp.1-13
• /
• 2009

느슨한 포화 사질토 층에 위치한 구조물은 지진 시 액상화로 인해 막대한 인적 경제적 피해가 발생하기 때문에 액상화 발생 가능 지반으로 분류된 지역은 구조물의 설계 및 운영 시 액상화 발생 가능성에 주의를 기울어야 한다. 한반도의 경우 중진 지역에 해당되고 역사 문헌의 발생 기록을 제외한 어떤 액상화 피해도 보고되지 않음에 따라 오랫동안 액상화에 대해서는 안전지대로 여겨져 왔다. 하지만, 최근 해외 지진 사례에 의하면 국내 서해안 지역 지반과 유사한 비소성 실트질 흙에서의 액상화 발생과 이로 인한 피해 사례가 종종 보고되고 있다. 본 연구에서는 국내에서의 액상화 가능성 평가 기법 합리화의 일환으로 서해안 두 부지를 대상으로 피에조콘 관입시험(CPTu)과 표준관입시험(SPT) 결과를 이용하여 액상화가능지수(LPI)를 산정하였다. LPI는 심도 20m까지의 액상화 가능성을 통합 적분하여 액상화로 인한 지표면 피해 발생 정도를 지수로 제시한다. 먼저 대상 현장에 대해 시나리오별 액상화 발생 가능성을 평가한 후, CPTu와 SPT로부터 산정된 LPI 값을 비교하였다. 액상화 저항 강도를 의미하는 진동저항응력비(CRR) 값에 의하면, CPTu로부터 구한 보정 콘 선단저항력 (qc1N)CS가 40에서 120 사이인 경우 또는 CRR이 0.23 이하인 경우에 SPT로부터의 산정된 값보다 작게 평가되었다. 또한 CRR 차이는 세립질 함유량이 큰 흙에서 두 방법 간의 차이가 더 크게 나타났다.

• 대한수의학회지
• /
• 제40권3호
• /
• pp.533-541
• /
• 2000

Biochemical and genetic analysis were carried out to investigate the potential recovery of pathogenecity or related mutations of Brucella abortus RB51 vaccine strains. RB51 strains were recovered from commercial vaccines, including related seed stocks from private companies in Republic of Korea, strain from USA, a reference strain from C university and a field isolate (Daehungjin) from aborted dairy cow after RB51 vaccination were compared with two identified virulent wild strains (S2308 and a field strain isolated from dairy cow in Korea) at the same conditions. All the strains examined, except identified pathogenic strains, revealed the identical characteristics to the original RB51 in biochemical properties, antigen and bacteriophage typing. Outer membrane protein (OMP) profiles from strains of RB51 showed the same patterns with standard RB51 in SDS-PAGE. In addition, Western blotting with the brucella specific monoclonal antibody also indicated that all the vaccine strains were completely deficient in their LPS compared to the pathogenic Br abortus strains. The differences in DNA structures among strains were also possible to detect after PCR. All vaccine strains, except S19, S1119-3, S1075, S544 and Br suis, were amplified a 178bp DNA fragment of eri-gene, and 364bp of IS711 elements. In contrast, 498bp DNA product was only found with Br abortus. Overall evidences in the present study confirmed that the RB51 strains for vaccine production in Korea did not originated from the phenomena of possible recovery of pathogenicity or related to any potential mutation event at all.

• 인지과학
• /
• 제20권1호
• /
• pp.29-49
• /
• 2009

본 연구의 목적은 Tanaka와 Shimojo의 제안처럼 회귀억제와 회귀촉진이 각각 두정엽 및 측두엽 경로의 정보처리와 관련성이 있는지를 검증하고 동시에 회귀억제와 회귀촉진 현상이 정보처리의 어느 단계에서 발생하는지 사건관련전위 기법을 이용하여 규명하는 것이었다. 이전 시행과 현재 시행에서 표적이 제시되는 위치의 일치성 여부에 따라서 일치조건과 불일치조건을 구별하고 탐지과제, 위치 변별과제, 색 변별과제, 방위 변별과제 수행시의 피험자의 반응시간과 사건관련전위를 측정하였다. 탐지과제와 위치 변별과제 수행 시 일치조건과 불일치조건 사이의 유의미한 반응시간 차이를 발견하지는 못하였다. 하지만, 색 변별과제와 방위 변별과제 수행 시 회귀촉진 현상을 발견하였다. 위치 변별과제 수행 시 Pz영역에서 일치조건과 불일치조건 사이의 유의미한 사건관련전위 차이를 발견하였으며 색 변별과제 과제 수행 시 T8 영역에서 두 조건 사이의 유의미한 사건관련 전위 차이를 발견하였고, 방위 변별과제 수행 시 T7/T8 영역에서 두 조건 사이의 유의미한 경향성을 발견하였다. 사건관련 전위의 차이는 특히 반응시간 전 단계에서 발견되었다. 이와 같은 실험결과는 제한적이기는 하지만 회귀억제와 회귀촉진이 정보처리 후기 단계인 반응 전 단계에서 각각 두정엽과 측두엽에서 발생할 가능성을 시사한다.