• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.532-548
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• 2021

Nuclear power plants contain several monitoring systems that can identify the in-vessel phenomena of a severe accident (SA). Though a lot of analysis and research is carried out on SA, right from the development of the nuclear industry, not all the possible circumstances are taken into consideration. Therefore, to improve the efficacy of the safety of nuclear power plants, additional analytical studies are needed that can directly monitor severe accident phenomena. This paper presents an interacting multiple model (IMM) based fault detection and diagnosis (FDD) approach for the identification of in-vessel phenomena to provide the accident propagation information using reactor vessel (RV) out-wall temperature distribution during severe accidents in a nuclear power plant. The estimation of wall temperature is treated as a state estimation problem where the time-varying wall temperature is estimated using IMM employing three multiple models for temperature evolution. From the estimated RV out-wall temperature and rate of temperature, the in-vessel phenomena are identified such as core meltdown, corium relocation, reactor vessel damage, reflooding, etc. We tested the proposed method with five different types of SA scenarios and the results show that the proposed method has estimated the outer wall temperature with good accuracy.

• Smart Structures and Systems
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• v.30 no.6
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• pp.639-648
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• 2022

This study aims at numerically and experimentally investigating torsional guided wave mixing with weak material nonlinearity under acoustoelastic effect in tubular structures. The acoustoelastic effect on single central frequency guided wave propagation in structures has been well-established. However, the acoustoelastic on guided wave mixing has not been fully explored. This study employs a three-dimensional (3D) finite element (FE) model to simulate the effect of stress on guided wave mixing in tubular structures. The nonlinear strain energy function and theory of incremental deformation are implemented in the 3D FE model to simulate the guided wave mixing with weak material nonlinearity under acoustoelastic effect. Experiments are carried out to measure the nonlinear features, such as combinational harmonics and second harmonics in related to different levels of applied stresses. The experimental results are compared with the 3D FE simulation. The results show that the generation combinational harmonic at sum frequency provides valuable stress information for tubular structures, and also useful for damage diagnosis. The findings of this study provide physical insights into the effect of applied stresses on the combinational harmonic generation due to wave mixing. The results are important for applying the guided wave mixing for in-situ monitoring of structures, which are subjected to different levels of loadings under operational condition.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.32-42
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• 2023

There are serious problems worldwide, such as a pandemic due to an unprecedented infection caused by COVID-19. On previous approaches, they invented medical vaccines and preemptive testing tools for medical engineering. However, it is difficult to access poor medical systems and medical institutions due to disparities between countries and regions. In advanced nations, the damage was even greater due to high medical and examination costs because they did not go to the hospital. Therefore, from a software engineering-based perspective, we propose a learning model for determining coronavirus infection through symptom data-based software prediction models and tools. After a comparative analysis of various models (decision tree, Naive Bayes, KNN, multi-perceptron neural network), we decide to choose an appropriate decision tree model. Due to a lack of data, additional survey data and overseas symptom data are applied and built into the judgment model. To protect from thiswe also adapt human normalization approach with traditional Korean medicin approach. We expect to be possible to determine coronavirus, flu, allergy, and cold without medical examination and diagnosis tools through data collection and analysis by applying decision trees.

• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.199-206
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• 2023

This study presents a novel monitoring technique for underwater high-voltage direct current (HVDC) cables based on the Distributed Acoustic Sensor (DAS). The proposed technique utilizes vibration and acoustic signals generated on HVDC cables to monitor their condition and detect events such as earthquakes, shipments, tidal currents, and construction activities. To implement the monitoring system, a DAS based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) system was designed, fabricated, and validated for performance. For the HVDC cable monitoring experiments, a testbed was constructed on land, mimicking the cable burial method and protective equipment used underwater. Defined various scenarios that could cause cable damage and conducted experiments accordingly. The developed DAS system achieved a maximum measurement distance of 50 km, a distance measurement interval of 2 m, and a measurement repetition rate of 1 kHz. Extensive experiments conducted on HVDC cables and protective facilities demonstrated the practical potential of the DAS system for monitoring underwater and underground areas.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.221-225
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• 2023

A female specimen of Sternuchopsis (s. str.) waltoni (Boheman, 1844), belonging to the tribe Mecysolobini (Curculionidae: Molytinae), was collected by beating method from Gadeok-do in Busan, the southern part of the Korean Peninsula. This weevil pest is designated as a quarantine pest under the Plant Quarantine Act (2019) in Korea. It is considered unreasonable to determine whether this species is an invasive or native species in Korea, as damage to crops has not been confirmed and there is no other collection information. This study aims to provide accurate diagnosis information including illustration and ecological information to gain more domestic occurrence information on this weevil.

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.42-48
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• 2023

An adult male Eurasian river otter (Lutra lutra) with ataxia and lethargy was rescued. Through the necropsy of this otter with neurological symptoms, a broad range of vascular damage caused by mercury toxicity in several organs, hepatocellular necrosis, and vacuolation in the brain. In mercury examination, liver, kidney, and hair showed values of 0.878 ± 0.027, 1.807 ± 0.049, and 5.712 ± 0.102 ㎍/g, respectively. Compared with certified reference material, it was confirmed that the concentration of mercury were 6.7 times, 13.7 times, and 43.3 times higher, respectively. When the symptoms and diagnosis results were comprehensively reviewed, this otter's demise was revealed due to mercury poisoning. The mercury concentration in the liver does not exceed the lowest observed effect level of 3.4 ㎍/g. However, even at low concentrations, long-term accumulation can cause symptoms including neuropathy, and the possibility that these heavy metals have accumulated in other wild animals cannot be ruled out. It seems that continuous monitoring using sentinel animals is necessary.

• The Journal of Internal Korean Medicine
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• v.45 no.1
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• pp.75-86
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• 2024

Spinal cord infarction is one of the rare strokes with no clear signs of serious nerve damage or after-effects. This study reports on the effectiveness of a combined treatment of Korean medicine and acupuncture on bilateral paraplegia, dysuria, and constipation in a patient with sudden-onset spinal cord infarction. An 84-year-old male patient was diagnosed with spinal cord infarction in August 2022. After diagnosis by whole spine MRI, he received treatment for two months at another hospital, but the improvement was insignificant. He then received Korean medicine treatment, and during this period, his lower extremity manual muscle test grade improved from 3 to 4 and his modified Rivermead mobility index score increased by 13 points, compared with hospitalization. Dysuria improved with acupuncture, and constipation improved with herbal medicine treatment. A combination of herbal medicine and acupuncture can be used to treat paraplegia, dysuria, and constipation caused by spinal cord infarction.

• Korean Journal of Radiology
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• v.1 no.2
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• pp.98-103
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• 2000

Objective: The purpose of this study was to describe the CT findings of hepatic hypereosinophilic syndrome in which hepatic lobes or segments were involved. Materials and Methods: Seven patients with hypereosinophilic syndrome with hepatic lobar or segmental involvement were included in our study. In all seven, diagnosis was based on liver biopsy and the results of corticosteroid treatment. CT findings were retrospectively reviewed by three radiologists, who reached a consensus. Biopsy specimens were examined, with special reference to portal and periportal inflammation. Results: CT demonstrated well-defined, homogeneous or heterogeneous low attenuation with a straight margin limited to a hepatic lobe (n = 2), segments (n = 3), or subsegments (n = 2), particularly during the portal phase. Where there was subsegmental involvement, lesions were multiple, ovoid or wedge-shaped, and showed low attenuation. In two patients with lobar or segmental involvement, segmental portal vein narrowing was observed. Histopathologic examination disclosed eosinophilic infiltration in the periportal area, sinusoids and central veins, as well as portal phlebitis. Conclusion: Hypereosinophilic syndrome may involve the presence of hepatic lobar, segmental, or subsegmental low-attenuated lesions, as seen on CT images. Their presence may be related to damage of the liver parenchyma and to portal phlebitis.

• Journal of Oral Medicine and Pain
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• v.49 no.1
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• pp.22-27
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• 2024

A 74-year-old female presented with a complaint of dry mouth, continuous spontaneous burning sensation in the tongue, and asymptomatic submucosal soft tissue mass on both sides of the lower labial mucosa. She refused to undergo total excision of the mass due to concern about the possibility of complications such as nerve damage because of the large size of the mass. As her clinical features and magnetic resonance imaging indicated the possibility of Sjögren's syndrome, a biopsy of the minor salivary gland of the right lower lip was performed. Consequently, she was diagnosed with mucosa-associated lymphoid tissue (MALT) lymphoma. Although the patient had typical signs and symptoms of Sjögren's syndrome, the histopathological result of MALT lymphoma made it impossible to determine whether the patient had a history of Sjögren's syndrome. For patients with risk factors for MALT lymphoma, such as Sjögren's syndrome, a biopsy of the labial minor salivary gland with immunohistochemical staining can be helpful in the diagnosis of not only Sjögren's syndrome but also MALT lymphoma.

• Pediatric Infection and Vaccine
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• v.11 no.1
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• pp.90-100
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• 2004

Objective : Urinary tract infection(UTI) is a frequent serious bacterial infection in young infants. The clinical presentation may be non-specific and variable, depends on factors such as the age and the level of infection. Children with renal involvement may be at risk of permanent renal damage. Experimental studies have shown that renal lesions caused by acute febrile UTI may be prevented or diminished by early diagnosis and treatment. Therefore, it is important to find a method that can permit early diagnosis and identification of patients who are at risk for progressive renal damage. We designed this study to identify related factors in culture positive UTI infants, and also to identify related factors in culture negative UTI infants, who are febrile with pyuria, by using renal imaging and functional studies including renal sonography, DMSA scan and VCUG. Methods : Retrospectively analyzed the medical records of 136 febrile infants with pyuria over 2 years(from January 2001 to February 2003). Urine culture was done in all cases, and regardless of urine culture findings, renal imaging study was done if symptomatic UTI suspected. Results : Total 57 organisms were isolated in 53 patients. E. coli was the most common organism(86%), followed by E. faecalis, M. morganii, Proteus species, P. aeruginosa, S. aureus and E. fergusonii. Most of the isolates had high sensitivity on cephalosporins or amikacin and had low sensitivities on aminopenicillins. Abnormal acute phase DMSA scan or VCUG findings were seen in both urine culture positive and negative group without statistical differences(P>0.05). In febrile infants with pyuria, fever over 48 hours, older age and high CRP related to abnormal acute phase DMSA scan findings regardless urine culture results. Conclusion : 1st or 3rd generation cephalosporins with amikacin could be the first choice of treatment for UTI. Febrile infants with positive urine culture dose mean urinary tract infection but not acute pyelonephritis which directly relates to cortical damage which could be confirmed by acute phase DMSA scan. Even cases with negative urine culture findings, acute pyelonephritis should be concerned in febrile infants with pyuria who are older than 3 months of age, has fever over 48 hours or high CRP level. And in such cases, acute phase DMSA scan and VCUG should be evaluated for early treatment and long term prognosis.