Risk-informed Emergency Response Training for Backdraft in Nuclear Power Plants

Mihyun Kim,Wonkook Kim,Hongki Kim,Jungman Kim,Sunhong Yoon,Jangwon Choi,Heemoon Kim 한국화재소방학회 2023 International Journal of Fire Science and Engineer Vol.37 No.3

Research has been conducted for developing fire evacuation and response training programs for nuclear power plant (NPP) application. Among numerous fire scenarios that may occur in an NPP environment, three different points of origin for a fire were selected for the program based on a risk-informed approach: switchgear room, main control room, and safety injection pump room. Fire outcomes were predicted for these scenarios via numerical modeling and the results were incorporated into the newly developed fire evacuation and response training program for the APR1400, Korea’s next-generation NPP model. The switchgear room fire scenario was found to have the most potential for backdraft to occur during manual fire response following automatic gaseous fire suppression system activation. The emergency response manual does discuss this possible backdraft occurrence; however, the guidance to avoid injuries is qualitative, such as to be cautious of backdrafts and wait a sufficient amount of time after opening a door before entering the. In this study, backdraft phenomenon that may occur from a switchgear room fire was numerically examined using the recent version of the Fire Dynamics Simulator to develop an appropriate timeline to be implemented in the fire evacuation and response training program. Based on the findings, the following guidance is provided: (1) backdraft can only occur when the fire originates in the space near the door; (2) wait at least 10 minutes after opening the door before entering the room; (3) watch for rapid smoke production, as this may be an antecedent phenomenon of backdraft; and (4) when smoke production increases rapidly, leave the room as soon as possible to avoid being caught within the deflagrating flames from a backdraft.

Assessment of Radiometric Degradation of FY-3A MERSI Reflective Solar Bands Using TOA Reflectance of Pseudoinvariant Calibration Sites

Wonkook Kim,Changyong Cao,Shunlin Liang IEEE 2014 IEEE geoscience and remote sensing letters Vol.11 No.4

<P>Radiometric sensor calibration is critical for quantitative use of the data obtained from the FeungYun-3A MEdium-Resolution Spectral Imager (MERSI) sensor. To meet the required calibration criteria, several vicarious calibration (VC) techniques are being employed in the current operational calibration of MERSI. This letter presents the independent results of sensor degradation assessment which were obtained directly from sequences of top-of-atmosphere (TOA) reflectance from calibration sites. The absolute calibration approaches and the desert tracking approach used in the current operational process involve a radiative transfer model (RTM) when simulating the reference TOA reflectance. However, collecting synchronous in situ measurements for an RTM is usually expensive and time consuming, thus greatly limiting the frequency of such calibration processes. The direct approach developed in this study is an efficient and complementary VC technique that can increase the reliability of VC results in concert with other techniques. TOA reflectance measurements from three pseudoinvariant calibration sites are used to estimate sensor degradation rates. The results are compared with those obtained by other operational methods such as the multisite and the deep convective cloud tracking methods. The direct approach is consistent across the three calibration sites, producing degradation estimates comparable to those of the two other operational methods, suggesting the effectiveness of the direct approach for the MERSI radiometric sensor calibration.</P>

Evaluation of chlorophyll retrievals from Geostationary Ocean Color Imager (GOCI) for the North-East Asian region

Kim, Wonkook,Moon, Jeong-Eon,Park, Young-Je,Ishizaka, Joji Elsevier 2016 Remote sensing of environment Vol.184 No.-

<P><B>Abstract</B></P> <P>Estimation of chlorophyll concentration in the marine biosphere has been the central topic of ocean color remote sensing since its advent. While various algorithms were proposed in the literature so far and tested for oceanic waters of diverse constituent composition, an independent algorithm evaluation is needed for local ocean waters that have dynamic variation in optically active water constituents such as colored dissolved organic matters (CDOM) and suspended particulate matter (SPM). This paper evaluates the performance of chlorophyll algorithms for Geostationary Ocean Color Imager (GOCI) radiometric data, using <I>in situ</I> measurements collected at 491 stations around Korea Peninsula during 2010–2014 from which there were 130 match-ups with GOCI data. For the evaluation in areas with high variation in SPM, water samples were first classified into three levels of SPM, and then the coefficients of candidate algorithms were newly derived for the turbidity cases using the <I>in situ</I> and GOCI remote sensing reflectance (<I>R</I> <SUB> <I>rs</I> </SUB>) data. Functional forms of traditional band ratio algorithms (<I>e.g.</I> OC algorithms (O′Reilly et al., 1998) and Tassan's algorithm (Tassan, 1994)), fluorescence line height algorithm, and near-infrared-to-red band ratio approach were tested. The evaluation results for the coincident <I>in situ</I> pairs of <I>R</I> <SUB> <I>rs</I> </SUB> and chlorophyll measurements showed that the mean uncertainty was <35% with the correlation around 0.8 by using the OC3 with turbidity consideration (OCT) and Tassan's algorithm with turbidity dependent coefficients (Tassan-TD). For the GOCI match-ups, the mean uncertainty for all turbidity levels was around 35% with correlation around 0.65, when OCT and Tassan-TD were used.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Evaluation of chlorophyll algorithms for Geostationary Ocean Color Imager (GOCI) </LI> <LI> <I>In situ</I> measurements from 491 stations in the North-East Asia ocean areas were used. </LI> <LI> Band ratio algorithms and fluorescence line height approach were tested for GOCI. </LI> <LI> Traditional algorithms exhibited large overestimation for turbid water samples. </LI> <LI> Uncertainty of 35% was achieved for GOCI by the algorithms with turbidity correction. </LI> </UL> </P>

원격 수질 측정을 위한 현장 초분광 복사계 및 수중 구성성분 관측 자료 분석

김원국(Kim, Wonkook),최준명(Choi, Jun Myoung) 한국측량학회 2018 한국측량학회지 Vol.36 No.4

스마트 연안·하천 관리를 위한 수질 원격탐사

김원국(Wonkook Kim) 대한토목학회 2019 대한토목학회지 Vol.67 No.9

GOCI-II Level 1B 분할영상 간의 복사 편차에 대한 초기 분석

김원국 ( Wonkook Kim ),임태홍 ( Taehong Lim ),안재현 ( Jae-hyun Ahn ),최종국 ( Jong-kuk Choi ) 대한원격탐사학회 2021 大韓遠隔探査學會誌 Vol.37 No.5

최근 성공적으로 발사되어 운영되고 있는 천리안 해양위성 2호(GOCI-II)는 3×4로 배열되어 있는 총 12장의 Level 1B분할영상을 통해 Local Area전체를 관측할 수 있다. 이 때 분할영상 간의 복사휘도의 차이가 발생하면 분할영상의 경계에서 불연속선이 나타나게 되는데, 그 불연속선은 2차 산출물에서 더 도드라지게 나타나는 경향이 있어 사용 전에 분할영상 간 복사휘도의 차이에 대한 면밀한 분석 및 교정이 필요하다. 본 연구는 분할영상 간에 존재하는 중첩 영역을 이용하여 복사휘도의 상대적인 편의를 추정하고자 한다. 신뢰도 높은 통계는 여러 날의 영상을 대량으로 분석해야 얻을 수 있겠지만, 본 초기 연구에서는 우선 한 시각에 촬영된 12개의 Level 1B 영상에 대한 통계를 도출함으로써 복사휘도 편차의 특성에 대해 이해하고 분산도 및 편의에 대한 전반적인 거동에 대한 분석을 수행한다. 사용 영상으로는 한반도 주변이 비교적 구름이 없는 날이었던 2021년 2월 21일 UTC03시 영상을 이용하였고, 신뢰도 높은 통계치 도출을 위하여 해양화소 만을 추출하여 사용하였다. 분석 결과는 밴드 1(380 nm)을 제외한 모든 밴드에서 0~1% 크기의 상대 편의가 나타남을 확인하였고, 밴드 1은 1~2% 가량의 보다 큰 편의를 보였다. 남북 방향으로 배열된 분할영상 쌍의 밴드 1의 경우를 제외하면, 동서, 남북 배열된 방향에 관계없이 모든 밴드에서 편의의 방향은 태양고도의 변화가 유발하는 편의의 방향과 반대로 나타났다. Geostationary Ocean Color Imager II (GOCI-II), which are now operated successfully since its launch in 2020, acquires local area images with 12 Level 1B slot images that are sequentially acquired in a 3×4 grid pattern. The boundary areas between the adjacent slots are prone to discontinuity in radiance, which becomes even more clear in the following Level 2 data, and this warrants the precise analysis and correction before the distribution. This study evaluates the relative radiometric biases between the adjacent slots images, by exploiting the overlapped areas across the images. Although it is ideal to derive the statistics from humongous images, this preliminary analysis uses just the scenes acquired at a specific time to understand its general behavior in terms of bias and variance in radiance. Level 1B images of February 21st, 2021 (UTC03 = noon in local time) were selected for the analysis based on the cloud cover, and the radiance statistics were calculated only with the ocean pixels. The results showed that the relative bias is 0~1% in all bands but Band 1 (380 nm), while Band 1 exhibited a larger bias (1~2%). Except for the Band 1 in slot pairs aligned North-South, biases in all direction and in all bands turned out to have biases in the opposite direction that the sun elevation would have caused.

로봇 동작 테스트를 위한 실제 환경의 온라인 디지털 트윈

신원국(Wonkook Shin),김도현(Dohyeon Kim),김준식(Jun-Sik Kim) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6

This paper proposes a digital twin approach that utilizes multiple camera sensors to construct a virtual environment synchronized with the real environment. A 3D reconstruction model of the real environment was generated using multiple camera sensors and the GPU-Voxels package. An efficient transformation process was proposed to make the generated data available for use in the Isaac SIM platform. It was confirmed that a virtual environment synchronized with the real environment was constructed in the Isaac SIM platform using the transformed data. Additional experiments verified that robot navigation tasks worked well in the constructed virtual environment.

드론과 기계학습을 이용한 항만시설 자동 변화탐지 기법 개발

김원국(Kim, Wonkook),Praja Chintya,백승일(Baek, Seung-Il) 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

다분광 광학 카메라를 이용한 수중 엽록소 추정을 위한 정밀 밴드간 형태학적 정합 기법

김원국(Kim, Wonkook),정성훈(Jung, Sunghun),문용선(Moon, Yongseon) 한국측량학회 2020 한국측량학회 학술대회자료집 Vol.2020 No.7

광학영상을 이용하면 엽록소 농도, 부유물 농도와 같은 수질을 원격으로 추정하는 것이 가능한데, 이를 위해서는 각 밴드간 영상의 접합이 정밀하게 이루어져야한다. 하지만, 다분광 영상에서 기하변환의 부정확성 및 각 밴드의 노출시간 차이 등으로 인하여, 각 픽셀에 있어서의 분광정보가 정확하게 정합되지 않는 경우가 발생한다. 이는 기존 투영기하(projective geometry)에 기반한 기하학적 변환으로도 해결하기 어려운 특성을 지니고 있다. 본 연구에서는 순서통계량(order statistics)를 이용하여 비강체 변환 (non-rigid body transformation) 대한 형태학적 정합 기법을 개발하여 수표면 영상에 적용하였다. Micasense Rededge-M 다분광 카메라를 드론에 설치하여 남해 연안에서 운용하였고, 수질 추정을 위하여 원격탐사 반사도를 산출하였다. 원격 수질 추정에 있어서 가장 중요한 변수인 엽록소 농도에 대하여 평가한 결과, 공간 해상도는 본 영상과 동일하게 유지되면서 기존 부정합에 의해 발생한 잡음이 대부분 제거되었다.

공동주택 관리비 등 체납에 따른 검토

김원국(WonKook Kim),임수영(Sooyoung Lim) 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.4

세상에 공짜란 없다고 한다. 즉, 모든 가치에는 값어치를 치루어야 한다는 것이다. 그리고 우리가 살고 있는 공동주택에서도 관리비를 비롯한 사용료 수수료 등 각종의 댓가를 치루어야만, 살 수 있는 시스템 속에 우리가 존재하고 있는 것이다. 그런데 일부의 사람들은 경제적인 이유를 비롯한 수많은 이유로 말미암아 관리비 등을 납부하지 못하고, 체납한 상태에서 공동주택에서 살고 있는 것으로 조사되고 있다. 공동주택관리법 시행령 제23조 제1항 및 별표2의 규정에 따라 관리비와 관련한 세목이 정해져 있는바, 의무관리대상 공동주택에서 거주하는 입주민들은 규정에 따라 관리비 납부의 의무가 발생하여 관리비 등을 납부하게 되는 것이다. 이에 따라 공동주택관리법에 의한 의무관리대상 공동주택의 관리주체는 관리소 및 공동주택 전체의 유지보수에 필요한 재원으로 사용하는 것이고, 그에 따른 혜택으로 입주민들은 주거의 안전과 쾌적한 삶을 보장 받게 되는 순환고리가 연결되어져 있는 것이다. 따라서 공동주택거주입주민 중 어느 한 가구에서 관리비 등이 체납되면 연쇄적으로 관리소 운영에까지 지대한 영향을 미치게 되는 것이다. 공동주택이 가지는 두 가지의 얼굴이 여기에서 나타나게 된다. 또 관리주체가 소멸시효완성 등의 사유로 체납관리비를 회수하지 못한 경우 입주자 대표회의 등에게 그 손해를 배상하여야 한다는 판결 및 관련 신문보도가 있는바, 체납관리비에 관한 분쟁발생에 대비하여야 한다는 책임감으로 연구를 한다. 공동주택의 관리비 등은 관련법령에서 자세하게 명시되어 있는바, 우리가 평소의 가지는 의문인 내가낸 관리비는 어떠한 기준에서 부과가 되고 어떻게 사용되어지고 있는지 등과 관련해서 자세하지는 않겠지만, 궁금증을 어느 정도 해소시켜줄 수 있기를 희망하며 논의를 이어가도록 할 것이다. There is no free trade in the world. That is, all values must be valued. And we have to live in a system where we have to pay for various expenses such as management fee and fee for use in the apartment where we live. However, some people have been unable to pay administrative expenses due to a number of reasons, including economic reasons. In accordance with Article 23, Paragraph 1 of the Enforcement Ordinance of the Apartment Housing Management Act and the annexed Table 2, the details related to the management expenses are set, and the residents residing in the compulsory apartment house are obliged to pay administrative expenses in accordance with the regulations.It is to be done. Accordingly, if one of the residents of an apartment house is in arrears on its administrative expenses, it could have a profound effect on the operation of the management office. The two faces of the apartments will be shown here. It also refers to the judgment that the managing body must compensate the unpaid administrative expenses to the residents representative meeting if it fails to recover them due to the fact that the statute of limitations has been completed, and the expenses incurred by the related newspaper are attributable to the failure to the report. The cost of managing an apartment is set forth in detail in the relevant law, but I would like to know what kind of standards we would like to discuss with regard to the cost of managing it.