• Title/Summary/Keyword: External Quality Assessment

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Residual Life Assessment on Cast Iron Pipes of Water Distribution System (상수도관로중 주철관종의 잔존수명 평가에 관한 연구)

  • Lee, Hyun-Dong;Bae, Chul-Ho;Hong, Seong-Ho;Hwang, Jae-Woon;Kwak, Phill-Jae
    • Journal of Korean Society on Water Environment
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    • v.20 no.3
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    • pp.206-214
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    • 2004
  • Residual wall thicknesses, corrosion rates, and residual life of thirty four samples of cast iron pipes(CIPs) and ductile cast iron pipes(DCIPs) collected from water mains of B city were studied to estimate their remaining service life or optimum time of rehabilitation. The internal maximum corrosion depths of samples measured using a dial gauge after shot blasting were twice higher than the external in most cases. Therefore corrosion of water pipes was much more affected by internal water quality than soil. Residual wall thicknesses of DCIPs were higher than those of CIPs. That reason was thought to be that DCIPs have been protected from internal corrosion by lining cement mortar. Residual life calculated by maximum corrosion rate was ranged up to 44 years with 12.40 years average. Since most CIPs were much deteriorated, rehabilitation plan should be established soon in B city. Residual life of DCIP was 33.52 years average. When cement mortar lining is used up by neutralization of DCIPs. DCIP also should be rehabilitated.

Analysis of stream flow and water quality variation by external flows to Mangyung watersheds using SWAT (SWAT 모형을 이용한 만경강 유역으로의 외부유입량에 따른 수문·수질 변동 분석)

  • Woo, So Young;Lee, Ji Wan;Kim, Seong Joon
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.41-41
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    • 2019
  • 동진강, 만경강 그리고 연안 유역으로 이루어진 새만금유역은 농업이 발달한 지역이지만 유역 내 이용 가능한 수자원량이 부족하여 인근 유역인 금강과 섬진강 유역으로부터 용수를 공급받고 있다. 외부유입량은 연도별 강수량 변화에 따라 편차가 크기 때문에 새만금유역은 극한 가뭄과 홍수에 더욱 취약한 유역이다. 또한, 간척사업으로 새만금 방조제 건설에 따라 유역의 수질 환경이 중요한 지역 사회의 이슈이며 특히 만경강의 경우 심각한 수질 문제를 개선하기 위한 다양한 연구가 수행되어왔다. 이에 따라 본 연구에서는 Soil and Water Assessment Tool (SWAT) 모형을 이용하여 만경강유역으로 들어오는 외부유입량 변화에 따른 유역의 수문 및 수질 변화 양상을 분석하여 수질 문제 개선 방안을 제시하고자 한다. 외부유입량 변동 시나리오는 만경강으로 유입되는 용담댐의 방류량을 이용하였으며, 기존 외부유입량 데이터에 비례하도록 산정하였다. SWAT 모형의 신뢰성 있는 모의를 위해 유역 외부에 위치한 용담댐의 운영을 별도로 고려하였고 취수를 통한 유역 내 농업용수 사용 등을 고려하였다. 수위-유량 관측소의 일자료와 수질관측소의 자료를 이용하여 유출량, SS, T-N, 그리고 T-P에 대한 보정(2012~2014) 및 검증(2016~2018)을 수행하였다. 각각의 검보정지점에 대한 $R^2$, NSE, RMSE을 목적 함수로 사용하여 모형의 적용성을 확인하였고, 이렇게 구축된 SWAT 모형을 기반으로 외부유입량 시나리오에 따른 유역의 수문 수질 변화를 분석하였다.

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The separation of arsenic metabolites in urine by high performance liquid chromatography-inductively coupled plasma-mass spectrometry

  • Chung, Jin-Yong;Lim, Hyoun-Ju;Kim, Young-Jin;Song, Ki-Hoon;Kim, Byoung-Gwon;Hong, Young-Seoub
    • Environmental Analysis Health and Toxicology
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    • v.29
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    • pp.18.1-18.9
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    • 2014
  • Objectives The purpose of this study was to determine a separation method for each arsenic metabolite in urine by using a high performance liquid chromatography (HPLC)-inductively coupled plasma-mass spectrometer (ICP-MS). Methods Separation of the arsenic metabolites was conducted in urine by using a polymeric anion-exchange (Hamilton PRP X-100, $4.6mm{\times}150mm$, $5{\mu}m$) column on Agilent Technologies 1260 Infinity LC system coupled to Agilent Technologies 7700 series ICP/MS equipment using argon as the plasma gas. Results All five important arsenic metabolites in urine were separated within 16 minutes in the order of arsenobetaine, arsenite, dimethylarsinate, monomethylarsonate and arsenate with detection limits ranging from 0.15 to $0.27{\mu}g/L$ ($40{\mu}L$ injection). We used G-EQUAS No. 52, the German external quality assessment scheme and standard reference material 2669, National Institute of Standard and Technology, to validate our analyses. Conclusions The method for separation of arsenic metabolites in urine was established by using HPLC-ICP-MS. This method contributes to the evaluation of arsenic exposure, health effect assessment and other bio-monitoring studies for arsenic exposure in South Korea.

Development and validation of novel simple prognostic model for predicting mortality in Korean intensive care units using national insurance claims data

  • Ah Young Leem;Soyul Han;Kyung Soo Chung;Su Hwan Lee;Moo Suk Park;Bora Lee;Young Sam Kim
    • The Korean journal of internal medicine
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    • v.39 no.4
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    • pp.625-639
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    • 2024
  • Background/Aims: Intensive care unit (ICU) quality is largely determined by the mortality rate. Therefore, we aimed to develop and validate a novel prognostic model for predicting mortality in Korean ICUs, using national insurance claims data. Methods: Data were obtained from the health insurance claims database maintained by the Health Insurance Review and Assessment Service of South Korea. From patients who underwent the third ICU adequacy evaluation, 42,489 cases were enrolled and randomly divided into the derivation and validation cohorts. Using the models derived from the derivation cohort, we analyzed whether they accurately predicted death in the validation cohort. The models were verified using data from one general and two tertiary hospitals. Results: Two severity correction models were created from the derivation cohort data, by applying variables selected through statistical analysis, through clinical consensus, and from performing multiple logistic regression analysis. Model 1 included six categorical variables (age, sex, Charlson comorbidity index, ventilator use, hemodialysis or continuous renal replacement therapy, and vasopressor use). Model 2 additionally included presence/absence of ICU specialists and nursing grades. In external validation, the performance of models 1 and 2 for predicting in-hospital and ICU mortality was not inferior to that of pre-existing scoring systems. Conclusions: The novel and simple models could predict in-hospital and ICU mortality and were not inferior compared to the pre-existing scoring systems.

A Study on the Water Quality Improvement of Major Tributaries in Seoul, Applying Watershed Evaluation Techniques (총량관리 단위유역 평가기법을 활용한 서울특별시 주요 유입 지천의 수질개선효과에 관한 연구)

  • Shim, Kyuhyun;Kim, Gyeonghoon;Im, Taehyo;Kim, Youngseok;Kim, Seongmin
    • Journal of Korean Society on Water Environment
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    • v.37 no.1
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    • pp.32-46
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    • 2021
  • South Korea has been divided into quantities and water quality, and due to a revision of the Government Organization law in June 2018, the controversial water management system was integrated into the Ministry of Environment. The total Maximum Daily Loads System has been called the flower of water quality control, and since 2004, all three major river systems which have been introduced into the Han River system, despite its various difficult environments, and subsequently leading to all of the four major rivers undergoing obligatory implementation since 2013. Currently, the target TMDL (Han River Phase 1 and Other Water Systems Phase 3) for the 2020 stage has been implemented. The domestic TMDL established a basic plan for calculating the load which complies with the unit watershed's target water quality, as well as an implementation plan for annual load management, both which have been institutionalized in order to evaluate load compliance on a repeated annual basis. Local governments ask external organizations to conduct investigations every year in order to assess the transition, which thereby requires tens of millions of won every year. Therefore, an assessment and management model that can be easily operated at the TMDL personnel level is required. In this study, when the Han river Water System TMDL was implemented in earnest, we confirmed the the water quality improvement effect when TMDL was introduced to major inflow tributaries (TancheonA, JungnangA, AnyangA) under the Seoul City's jurisdiction through the use of the total amount control unit basin evaluation technique. By presenting customized management measures, we propose the guidelines that are necessary for determining more effective water environmental policies.

Quality of Radiomics Research on Brain Metastasis: A Roadmap to Promote Clinical Translation

  • Chae Jung Park;Yae Won Park;Sung Soo Ahn;Dain Kim;Eui Hyun Kim;Seok-Gu Kang;Jong Hee Chang;Se Hoon Kim;Seung-Koo Lee
    • Korean Journal of Radiology
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    • v.23 no.1
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    • pp.77-88
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    • 2022
  • Objective: Our study aimed to evaluate the quality of radiomics studies on brain metastases based on the radiomics quality score (RQS), Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) checklist, and the Image Biomarker Standardization Initiative (IBSI) guidelines. Materials and Methods: PubMed MEDLINE, and EMBASE were searched for articles on radiomics for evaluating brain metastases, published until February 2021. Of the 572 articles, 29 relevant original research articles were included and evaluated according to the RQS, TRIPOD checklist, and IBSI guidelines. Results: External validation was performed in only three studies (10.3%). The median RQS was 3.0 (range, -6 to 12), with a low basic adherence rate of 50.0%. The adherence rate was low in comparison to the "gold standard" (10.3%), stating the potential clinical utility (10.3%), performing the cut-off analysis (3.4%), reporting calibration statistics (6.9%), and providing open science and data (3.4%). None of the studies involved test-retest or phantom studies, prospective studies, or cost-effectiveness analyses. The overall rate of adherence to the TRIPOD checklist was 60.3% and low for reporting title (3.4%), blind assessment of outcome (0%), description of the handling of missing data (0%), and presentation of the full prediction model (0%). The majority of studies lacked pre-processing steps, with bias-field correction, isovoxel resampling, skull stripping, and gray-level discretization performed in only six (20.7%), nine (31.0%), four (3.8%), and four (13.8%) studies, respectively. Conclusion: The overall scientific and reporting quality of radiomics studies on brain metastases published during the study period was insufficient. Radiomics studies should adhere to the RQS, TRIPOD, and IBSI guidelines to facilitate the translation of radiomics into the clinical field.

Evaluation of Ecosystem Service for Distribution of Korean fir using InVEST Model (InVEST모델을 이용한 생태계서비스의 가치 평가 - 구상나무 분포지를 대상으로 -)

  • Choi, Jiyoung;Lee, Sangdon
    • Journal of Environmental Impact Assessment
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    • v.27 no.2
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    • pp.181-193
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    • 2018
  • The present study was conducted to analyze the quality of the habitats of Abies koreana WILS. by using the InVEST model based on the analytic hierarchy process (AHP) technique and to evaluate the economic value by estimating the carbon fixation. Abies koreana WILS., an original biological species of South Korea, may be an essential element in establishing the national biological sovereignty in the future. The subjects of the present study were the national parks in Mt. Halla, Mt. Jiri, and Mt. Sobaek, which are the habitats of Abies koreana WILS. As suggested by previous studies as a limitation of the InVEST model, the utilization of the data from relevant international publications as the input data, due to the lack of the domestic input data, may decrease the accuracy of the modeling. Therefore, the AHP technique was applied for the input data. The modeling was performed with reference to the years of 1980, 1990, and 2000 for the scenario analysis. The result of the modeling showed that the habitat quality was changed most in the national park in Mt. Halla, as the habitat quality score was decreased from 0.96 in 1980 to 0.97 in 1990 and 0.94 in 2000. In the national part of Mt. Sobeak, the habitat quality was changed most in the sub-alpine zone, as the habitat quality score was decreased from 0.98 in 1980 and 0.98 in 1990 to 0.97 in 2000. The habitat quality was best conserved in the national part in Mt. Jiri, as the habitat quality score was 0.98 in 1980, 0.99 in 1990, and 0.99 in 2000. The estimated economic loss by the change of the habitat quality was 19,280,000 USD for Mt. Halla and 8,030,000 USD for Mt. Sobeak. In the present study, the habitat quality of the Abies koreana WILS, the original species of South Korea, was evaluated and the economic value of the ecological services provided by the habitats was estimated quantitatively. The result showed that the ecosystem service model may be used to qualitatively analyze the quality of a habitat located in a specific region and to estimate the economic value quantitatively. The objective evaluation of ecosystem services demonstrated in the present study may be applied to promote sustainable utilization of natural resources and conservation of the ecosystem by predicting the changes that may be caused by external factors including the development of preservation areas.

Online Refocusing Algorithm Considering the Tilting Effect for a Small Satellite Camera (위성 카메라의 틸트 효과를 고려한 온라인 리포커싱 알고리즘)

  • Lee, Da Hyun;Hwang, Jai Hyuk;Hong, Dae Gi
    • Journal of Aerospace System Engineering
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    • v.12 no.4
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    • pp.64-74
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    • 2018
  • Small high-resolution Earth observation satellites require precise optical alignment at the submicron level. However, misalignments can occur due to the influence of external factors during the launch and operation despite the sufficient alignment processes that take place before the launch. Thus, satellites need to realign their optical elements in orbit in what is known as a refocusing process to compensate for any misalignments. Refocusing algorithms developed for satellites have only considered de-space, which is the most sensitive factor with respect to image quality. However, the existing algorithms can cause correction error when inner and external forces generate tilt amount in an optical system. The present work suggests an improved online refocusing algorithm by considering the tilting effect for application in the case of a de-spaced and tilted optical system. In addition, the algorithm is considered to be efficient in terms of time and cost because it is designed to be used as an online method that does not require ground communication.

The Auditors' Responses to Management's Overconfident Tone Depending on the Level of Earnings Management (경영자의 자기과신적 어조 및 이익조정에 대한 감사인의 반응)

  • Hee-Yeon Sunwoo;Hyejeong Shin
    • Journal of East Asia Management
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    • v.4 no.1
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    • pp.23-51
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    • 2023
  • We investigate whether the association between management overconfident tone and the level of audit effort measured by audit fees and hours differs depending on the level of earnings management. Prior studies suggest that firms led by overconfident managers are likely to initiate risky investments, report low quality financial statements, and have material weaknesses in internal control system. These characteristics, combined together, result in higher audit risk. At the same time, auditors assess audit risk based on the quality of financial reporting, measured by level of earnings management. As a result, the assess audit risk is likely to reflect the combined effect of management overconfidence and the level of earnings management. In this paper, we investigate whether auditors differentiate the effects of real earnings management (REM) and accrual-based earnings management (AEM) when they assess the audit risk related management overconfident. Using the CEO's letter published in 2018, we measure the CEO's tone representing the degree of overconfidence (i.e., activity). Based on this measure, we find that the positive association between managerial overconfident tone and audit effort is more pronounced as the level of REM is higher. However, we find that the baseline association does not vary depending on the level of AEM. These results suggest that auditors consider the managerial overconfident severer when such characteristic accompany the higher level of REM, which can be outcome of aggressive business decisions possibly leading to the higher audit risks. We further find that these results are stronger for Big 4 auditors and continuing auditors. This paper contributes to the literature and practice as follows. First, we provide contextual evidence on how auditors reflect managerial characteristics in the audit process by documenting that auditors actively increase their audit efforts only when overconfident managerial characteristics are highly likely to lead to audit risk. This result suggests that auditors conduct external auditing considering both the efficiency and effectiveness of the audit process. Second, we suggest that auditors use information obtained from a wide range of sources to identify audit risks. Our results provide evidence of how the auditing standards, which do not provide detailed guidelines for audit risk assessment, are being applied in practice. Finally, our results also enhance the understanding of how audit fees are determined. Combined with the studies related to audit pricing, we provide the important reference for discussion between the auditor and the auditee about the audit fee that has created acute tension after the enforcement of the new External Audit Act.

Present Status of the Quality Assurance and Control (QA/QC) for Korean Macrozoobenthic Biological Data and Suggestions for its Improvement (해양저서동물의 정량적 자료에 대한 정도관리 현실과 개선안)

  • CHOI, JIN-WOO;KHIM, JONG SEONG;SONG, SUNG JOON;RYU, JONGSEONG;KWON, BONG-OH
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.26 no.3
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    • pp.263-276
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    • 2021
  • Marine benthic organisms have been used as the indicators for the environment assessment and recently considered as a very important component in the biodiversity and ecosystem restoration. In Korean waters, the quantitative data on marine benthos was used as one of major components for the marine pollution assessment for 50 years since 1970s. The species identification which is an important factor for the quantitative biological data was mainly performed by the marine benthic ecologists. This leads to the deterioration of the data quality on marine benthos from the misidentication of major taxonomic groups due to the lack of taxonomic expertise in Korea. This taxonomic problem has not been solved until now and remains in most data from national research projects on the marine ecosystems in Korean waters. Here we introduce the quality assurance and control (QA/QC) system for the marine biological data in UK, that is, NMBAQC (Northeast Atlantic Marine Biological Analytic and Quality Control) Scheme which has been performed by private companies to solve similar species identification problems in UK. This scheme asks for all marine laboratories which want to participate to any national monitoring programs in UK to keep their identification potency at high level by the internal quality assurance systems and provides a series of taxonomic workshops and literature to increase their capability. They also performs the external quality control for the marine laboratories by performing the Ring Test using standard specimens on various faunal groups. In the case of Korea, there are few taxonomic expertise in two existing national institutions and so they can't solve the taxonomic problems in marine benthic fauna data. We would like to provide a few necessary suggestions to solve the taxonomic problems in Korean marine biological data in short-terms and long-terms: (1) the identification of all dominant species in marine biological data should be confirmed by taxonomic expertise, (2) all the national research programs should include taxonomic experts, and (3) establishing a private company, like the Korea marine organism identification association (KMOIA), which can perform the QA/QC system on the marine organisms and support all Korean marine laboratories by providing taxonomic literature and species identification workshops to enhance their potency. The last suggestion needs more efforts and time for the establishment of that taxonomic company by gathering the detailed contents and related opinions from diverse stakeholders in Korea.