Identification Scheme for the Affine Sensor Model

Donghoon Kang,Jong-Phil Kim,Jinwook Kim,Heedong Ko 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

In this article, we present a robust auto-calibration scheme of the affine sensor model via the spectral decomposition of scale factor matrix and the semi-definite programming (SDP). Inherent benefits of our scheme are the globally optimal estimation of calibration parameters without any additional measurement equipment.

Interdependence between iron acquisition and biofilm formation in Pseudomonas aeruginosa

Donghoon Kang,Natalia V. Kirienko 한국미생물학회 2018 The journal of microbiology Vol.56 No.7

Bacterial biofilms remain a persistent threat to human healthcare due to their role in the development of antimicrobial resistance. To combat multi-drug resistant pathogens, it is crucial to enhance our understanding of not only the regulation of biofilm formation, but also its contribution to bacterial virulence. Iron acquisition lies at the crux of these two subjects. In this review, we discuss the role of iron acquisition in biofilm formation and how hosts impede this mechanism to defend against pathogens. We also discuss recent findings that suggest that biofilm formation can also have the reciprocal effect, influencing siderophore production and iron sequestration.

Outcomes Associated With ABCG2 and CD133 Expression in Patients With Gastric Cancer After Surgical Resection

Donghoon Kang,Jae Myung Park,Sung Hak Lee,Yu Kyung Cho,Bo-In Lee,Myung-Gyu Choi 대한상부위장관ㆍ헬리코박터학회 2023 Korean Journal of Helicobacter Upper Gastrointesti Vol.23 No.4

Objectives: Adenosine triphosphate-binding cassette subfamily G member 2 (ABCG2) and CD133 are recognized stem cell markers of gastric cancer. Extensive research has examined the significance of these markers in different types of cancers and their impact on prognoses, linking them to unfavorable clinical outcomes in various tumors. However, the prognostic value of these markers for gastric cancer remains unclear. We investigated the expression of ABCG2 and CD133 and their relationship with clinical outcomes in gastric cancer.Methods: ABCG2 and CD133 expression levels were analyzed, using immunohistochemistry and tissue microarrays, in tumor samples from 459 patients who underwent surgical resections due to gastric cancer. ABCG2 and CD133 expression levels were defined by intensity and dichotomized as medians. The associations among the expression levels of these markers, disease severity, and patient survival were also determined.Results: In the 411 patients for whom we analyzed the expression levels of these markers, 74.9% and 80.5% were found to have high levels of ABCG2 and CD133, respectively. High expression levels of ABCG2 and CD133 were more commonly observed in well-differentiated (<i>p</i><0.001 and <i>p</i>=0.004, respectively) and intestinal lesions (<i>p</i><0.001 and <i>p</i>=0.002, respectively). High ABCG2 expression correlated with improved survival outcomes, whereas high CD133 expression was associated with poorer outcomes. Cox regression analysis confirmed that stage, high ABCG2 (overall survival [OS]: hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.41–0.91; <i>p</i>=0.015; recurrencefree survival [RFS]: HR, 0.55; 95% CI, 0.34–0.88; <i>p</i>=0.012), and CD133 expression (OS: HR, 1.59; 95% CI, 1.00–2.51; <i>p</i>=0.049; RFS: HR, 2.29; 95% CI, 1.21–4.34; <i>p</i>=0.011) were predictors of survival. A subgroup analysis indicated that ABCG2 expression was also associated with an improved RFS rate in patients who received systemic chemotherapy.Conclusions: High ABCG2 expression and low CD133 expression in tumors correlated with improved survival outcomes in post-resection patients with gastric cancer, suggesting their potential utility as prognostic biomarkers.

A Case of Gastric heterotopic pancreatitis clinically diagnosed without surgical resection

( Donghoon Kang ),( Jae Myung Park ) 대한내과학회 2015 대한내과학회 추계학술대회 Vol.2015 No.1

Heterotopic pancreas is a rare condition which is defined as the presence of pancreatic tissue without anatomical and vascular continuity with the pancreas. Stomach is one of the most commonly involved site, but usually asymptomatic. Here we report an unusual case of gastric heterotopic pancreatitis causing epigastric pain and mimicking gastric abscess, which was diagnosed preoperatively using endoscopic ultrasonography and serological markers. A 46-year-old male visited emergency department due to epigastric pain and fever developed one day before. His laboratory data suggested systemic inflammation with mild elevation of lipase level. Initial CT scan showed thickened gastric wall at antrum. Subsequent gastroduodenoscopy, endoscopic ultrasound (EUS), and stomach MRI showed that marked gastric wall thickening with heterogenous echogenicity, irregularity of gastric wall and multiple cystic small abscesses mostly confined in serosa. Accordingly, we presumed gastric abscesses and started treatment with intravenous hydration and antibiotics. After 2 days, serum amylase and lipase level went up to the peak level, but decreased by continuing treatment. So we diagnosed gastric heterotopic pancreatitis. He was discharged with better well-being sensation and decreased serum amylase and lipase level. In outpatient’s office, follow-up endoscopy, EUS and blood tests were done and showed improvements.

Auditory Training Using Remembering the Order of Sentences for the Elderly Who Wear Hearing Aids: Is it Effective for Speech Perception in Noise, Working Memory and Reasoning Ability?

Donghoon Kang,So Hyun Kim,Dajung Yun,Junghwa Bahng 한국청각언어재활학회 2020 Audiology and Speech Research Vol.16 No.2

Purpose: The present study examines auditory training outcomes in terms of speech perception in noise, working memory, reasoning ability, and subjective hearing aid satisfaction. Methods: Ten older adults who wear hearing aids (mean age: 71.6) voluntarily participated in the study. For the training material, 78 sentence sets composed of 3 to 5 sentences were used. During the auditory training, participants tried to remember the order of sentences. Among the 78 sentence sets, 45 contained clues and the rest did not. Each participant underwent assessments including speech perception in noise and digit spans and reasoning test and completed a self-report hearing aid satisfaction questionnaire both pre- and post-auditory training. The participants completed eight sessions of the auditory training. Results: The results showed a statistically significant increase in speech recognition ability in noise, short-term memory, and working memory, as well as satisfaction with hearing aid use. Despite a slight increase on the reasoning test, there was no statistically significant improvement. Conclusion: The results of this study suggested that the auditory training in remembering the order of sentences improved speech perception in noise, sensory and working memory, and subjective satisfaction with hearing aids. Future research can investigate more effective auditory training tools to improve the various cognitive skills and communication ability of older adults who wear hearing aids.

Effect of Aging on the Corrosion Resistance of 2209 Duplex Stainless Steel Weldments

Donghoon Kang,Nohoon Kim,Haewoo Lee 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3

In this study, we investigated the correlation between the microstructure and the localized corrosion characteristics for a weldmetal made up of 22Cr-9Ni duplex stainless steel (DSS) aged in the range of 400–1000 °C for 30 min. The results showedthat changes in the microstructure of the DSS weldments, owing to the formation of precipitates during the aging process,affected its pitting corrosion resistance. The microstructural evolution was found to be extremely sensitive to the secondaryphase precipitations such as chi (χ), sigma (σ), chromium nitride (Cr2N), and secondary austenite (γ2) in the aging range of700–900 °C. The potentiodynamic polarization tests confirmed that the pitting potential representing the corrosion resistancedecreased gradually from 500 °C, attained the lowest at 850 °C, and increased again at 900 °C. In addition, the Cr orMo deficient area around σ phase was transformed into the secondary austenite (γ2) phase during aging where the pittingwas found to occur.

Unscented Kalman Filtering for Simultaneous Estimation of Attitude and Gyroscope Bias

Kang, Donghoon,Jang, Cheongjae,Park, Frank C. IEEE 2019 IEEE/ASME transactions on mechatronics Vol.24 No.1

<P>We present an unscented Kalman filtering algorithm for simultaneously estimating attitude and gyroscope bias from an inertial measurement unit (IMU). The algorithm is formulated as a discrete-time stochastic nonlinear filter, with state space given by the direct product matrix Lie group <TEX>$\text{SO(3)} \times \mathbb {R}^3$</TEX>, and observations in <TEX>$\text{SO(3)}$</TEX> reconstructed from IMU measurements of gravity and the earth's magnetic field. Computationally efficient implementations of our filter are made possible by formulating the state space dynamics and measurement equations in a way that leads to closed-form equations for covariance propagation and update. The resulting attitude estimates are invariant with respect to choice of fixed and moving reference frames. The performance advantages of our filter vis-à-vis existing state-of-the-art IMU attitude estimation algorithms are validated via numerical and hardware experiments involving both synthetic and real data.</P>

Heating performance of a VRF heat pump system incorporating double vapor injection in scroll compressor

Kang, Donghoon,Jeong, Ji Hwan,Ryu, Byoungjin Elsevier 2018 International Journal of Refrigeration Vol.96 No.-

<P><B>Abstract</B></P> <P>Heat pumps with a vapor injection cycle are currently used to compensate for heating capacity degradation at lower outdoor temperatures. A double vapor injection system with a scroll compressor was developed in order to enhance the vapor injection technique. The heating performance of the variable refrigerant flow heat pump systems employing non-vapor injection, single vapor injection, and double vapor injection was experimentally investigated. At the compressor frequencies of 90, 110, and 150 Hz, the heating capacities of the double vapor injection system were improved by 8.9, 12.1, and 18.9%, respectively, compared to those of the single-vapor injection system; and the coefficient of performances (COPs) were improved by 5.8, 8.6, and 9.8%, respectively. The double vapor injection system appeared to be superior to the single vapor injection system in terms of heating capacity and COP.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three-stage scroll compressor was developed for double vapor injection cycle. </LI> <LI> The effect of vapor injection model on heating performance was investigated. </LI> <LI> Experimental investigation on double vapor injection heat pump. </LI> <LI> Enlarged COP and heating capacity than conventional single vapor injection. </LI> </UL> </P>

Evaluation on Applicability of Paint-Type Exothermic Coating System on Railway Vehicle in Winter Season

Donghoon Kang(강동훈),Heonyoung Kim(김헌영),Kyungwho Choi(최경후) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

Affine registration of three-dimensional point sets for improving the accuracy of eye position trackers

Kang, Donghoon,Kim, Jinwook,Kim, Sung-Kyu SPIE - International Society for Optical Engineeri 2017 Optical engineering Vol.56 No.4