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Lee Kwang Min,Lee Seungho,Kim Yoon-Ji,Lee Seung Eun,Kim Youngki,Kang Dongmug,Kim Se-Yeong 대한직업환경의학회 2023 대한직업환경의학회지 Vol.35 No.1
Background: Indoor air pollution can cause and exacerbate asthma. We report a previously undescribed case of occupational asthma related to indoor air pollution in a worker at an indoor air gun shooting range and highlight the potential risk of developing occupational asthma in this environment. Case presentation: A 31-year-old man presented with dyspnea, cough, and sputum and was diagnosed with asthma complicated by pneumonia. Objective evidence of asthma was obtained by performing a methacholine bronchial provocation test. It was suspected that the patient had occupational asthma, which began one month after changing jobs to work within the indoor air gun shooting range. The highest peak expiratory flow (PEF) diurnal variability on working days was 15%, but the highest variation was 24%, with 4 days out of 4 weeks having a variation of over 20% related to workplace exposure. Conversely, the diurnal variability on the rest days was 7%, and no day showed a variation exceeding 20%. The difference in the average PEF between working and rest days was 52 L/min. PEF deterioration during working days and improvement on rest days were noted. Conclusions: The results obtained from the in-depth analysis of the PEF were adequate to diagnose the patient with occupational asthma. Exposure to indoor air pollution and lead and the patient’s atopy and allergic rhinitis may have contributed to the development of occupational asthma.
Youngki Lee,Seokjin Hong,김정표,최재훈 한국전자통신연구원 2010 ETRI Journal Vol.32 No.1
In this paper, an ultra-wideband internal antenna for use in mobile applications is proposed. The proposed antenna has symmetrical bi-arm structures printed on the top and bottom of the substrate, and it occupies a compact area of 10 mm × 10 mm × 1 mm. The designed antenna has an impedance bandwidth from 3 GHz to 12 GHz and near omnidirectional radiation patterns over the frequency band of interest. The group delay between two antennas fabricated using the proposed design is less than 0.8 ns, and the maximum gain variation is about 3.16 dB.
A Compact On-Frequency Indoor Repeater Antenna with High Isolation for WCDMA Applications
LEE, Youngki,KIM, Jeongpyo,CHOI, Jaehoon The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.12
<P>In this paper, an indoor repeater antenna with high isolation for WCDMA application is proposed. The designed repeater has very small separation of 20mm between the donor and server antennas. The antenna has two resonance frequencies to cover the WCDMA band from 1.92GHz to 2.17GHz. The fabricated antenna has VSWR below 1.5, gain over 8dBi, and isolation between server and donor antennas less than -80dB in the WCDMA band.</P>
Antitumor Effect of Metformin in Combination with Binimetinib on Melanoma Cells
Lee, Eunsung,Kwon, Yongjae,Kim, Jiwon,Park, Deokbae,Lee, Youngki The Korean Society of Developmental Biology 2021 발생과 생식 Vol.25 No.2
Cutaneous melanoma is a fatal disease for patients with distant metastasis. Metformin is the most widely used anti-diabetic drug, and proved to suppress cell proliferation and metastasis in diverse cancers including melanoma. We previously reported that MEK inhibitor trametinib increases the expression of epithelial-mesenchymal transition (EMT) regulators and melanoma cell motility, which are suppressed by addition of metformin in A375 melanoma cells. To confirm our findings further, we first evaluated the effect of metformin in combination with another MEK inhibitor binimetinib on cell viability in G361 melanoma cells. We then investigated whether binimetinib affects the expression of EMT regulators and cell motility. We finally monitored the effect of metformin on binimetinib-induced cell migration. Cell viability assay showed that combination index (CI) value at ED<sub>50</sub> is 0.80, suggesting synergy for the combination of metformin with binimetinib. Our results also revealed that binimetinib increased the expression of EMT regulators such as integrin αV, fibronectin and slug, which correlate well with the enhanced cell migration in wound healing assay. Metformin, on the contrary, suppressed the expression of sparc, integrin αV, fibronectin and N-cadherin with the reduced cell motility. The combination treatment showed that metformin counteracts the binimetinib-induced increase of cell motility. Overall, these results suggest that metformin with binimetinib might be useful as a potential therapeutic adjuvant against cell survival and metastatic activity in melanoma patients.
CoMon+: A Cooperative Context Monitoring System for Multi-Device Personal Sensing Environments
Lee, Youngki,Kang, Seungwoo,Min, Chulhong,Ju, Younghyun,Hwang, Inseok,Song, Junehwa IEEE Computer Society 2016 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.15 No.8
<P>Continuous mobile sensing applications are emerging. Despite their usefulness, their real-world adoption has been slow. Many users are turned away by the drastic battery drain caused by continuous sensing and processing. In this paper, we propose CoMon+, a novel cooperative context monitoring system, which addresses the energy problem through opportunistic cooperation among nearby users. For effective cooperation, we develop a benefit-aware negotiation method to maximize the energy benefit of context sharing. CoMon+ employs heuristics to detect cooperators who are likely to remain in the vicinity for a long period of time, and the negotiation method automatically devises a cooperation plan that provides mutual benefit to cooperators, while considering running applications, available devices, and user policies. Especially, CoMon+ improves the negotiation method proposed in our earlier work, CoMon [30], to exploit multiple processing plans enabled by various personal sensing devices; each plan can be alternatively used for cooperation, which in turn will maximize overall power saving. We implement a CoMon+ prototype and show that it provides significant benefit for mobile sensing applications, e.g., saving 27-71 percent of smartphone power consumption depending on cooperation cases. Also, our deployment study shows that CoMon+ saves an average 19.7 percent of battery under daily use of a prototype application compared to the case without CoMon+ running.</P>
Scalable Activity-Travel Pattern Monitoring Framework for Large-Scale City Environment
Youngki Lee,SangJeong Lee,Byoungjip Kim,Jungwoo Kim,Yunseok Rhee,Junehwa Song IEEE 2012 IEEE transactions on mobile computing Vol.11 No.4
<P>In this paper, we introduce Activity Travel Pattern (ATP) monitoring in a large-scale city environment. ATP represents where city residents and vehicles stay and how they travel around in a complex megacity. Monitoring ATP will incubate new types of value-added services such as predictive mobile advertisement, demand forecasting for urban stores, and adaptive transportation scheduling. To enable ATP monitoring, we develop ActraMon, a high-performanceATP monitoring framework. As a first step, ActraMon provides a simple but effective computational model of ATP and a declarative query language facilitating effective specification of various ATP monitoring queries. More important, ActraMon employs the shared staging architecture and highly efficient processing techniques, which address the scalability challenges caused by massive location updates, a number of ATP monitoring queries and processing complexity of ATP monitoring. Finally, we demonstrate the extensive performance study of ActraMon using realistic city-wide ATP workloads.</P>
Improving the Isolation of MIMO Antennas Using Split Ring Resonators
Youngki Lee,Haeil Chung,Jaehoon Choi 한국전자파학회JEES 2010 Journal of Electromagnetic Engineering and Science Vol.10 No.4
This paper proposes a method for improving the isolation characteristic of multi-input multi-output (MIMO) antennas using a split ring resonator (SRR) array structure between the two radiating elements. The fabricated antenna satisfies the 10 ㏈ return loss requirement in the Mobile-WiMAX frequency band from 3.4 ㎓ to 3.6 ㎓. The isolation between the two radiating elements is improved by approximately 20 ㏈ at the center frequency by inserting a SRR array structure. The measured peak gains of the two elements are 2.3 ㏈i and 2.4 ㏈i, respectively.
Metformin Synergistically Potentiates the Antitumor Effects of Imatinib in Colorectal Cancer Cells
Lee, Jaeryun,Park, Deokbae,Lee, Youngki The Korean Society of Developmental Biology 2017 발생과 생식 Vol.21 No.2
Metformin is the most commonly prescribed anti-diabetic drug with relatively minor side effect. Substantial evidence has suggested that metformin is associated with decreased cancer risk and anticancer activity against diverse cancer cells. The tyrosine kinase inhibitor imatinib has shown powerful activity for treatment of chronic myeloid leukemia and also induces growth arrest and apoptosis in colorectal cancer cells. In this study, we tested the combination of imatinib and metformin against HCT15 colorectal cancer cells for effects on cell viability, cell cycle and autophagy. Our data show that metformin synergistically enhances the imatinib cytotoxicity in HCT15 cells as indicated by combination and drug reduction indices. We also demonstrate that the combination causes synergistic down-regulation of pERK, cell cycle arrest in S and $G_2/M$ phases via reduction of cyclin B1 level. Moreover, the combination resulted in autophagy induction as revealed by increased acidic vesicular organelles and cleaved form of LC3-II. Inhibition of autophagic process by chloroquine led to decreased cell viability, suggesting that induction of autophagy seems to play a cell protective role that may act against anticancer effects. In conclusion, our present data suggest that metformin in combination with imatinib might be a promising therapeutic option in colorectal cancer.