• Journal of Power Electronics
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• v.19 no.3
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• pp.637-644
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• 2019

Wireless power transfer (WPT) technology with various transfer mechanisms such as inductive coupling, magnetic resonance and capacitive coupling is being widely researched. Until now, power transfer efficiency (PTE) and power transfer capability (PTC) have been the primary concerns for designing and developing WPT systems. Therefore, a lot of studies have been documented to improve PTE and PTC. However, power consumption in the standby mode, also defined as the no-load mode, has been rarely studied. Recently, since the number of WPT products has been gradually increasing, it is necessary to develop techniques for reducing the standby power consumption of WPT systems. This paper investigates the standby power consumption of commercial WPT products. Moreover, a standby power reduction technique for WPT systems via magnetic resonance coupling (MRC) with a parallel resonance type resonator is proposed. To achieve a further standby power reduction, the voltage control of an AC/DC travel adapter is also adopted. The operational principles and characteristics are described and verified with simulation and experimental results. The proposed method greatly reduces the standby power consumption of a WPT system via MRC from 2.03 W to 0.19 W.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.933-940
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• 2017

A wireless power transfer system with a negative impedance converter(NIC) was designed and tested. The system was investigated to identify the effects of ferrites and conductors. To improve the power transfer efficiency(PTE), the Q-factor of the transmitter was enhanced by the negative resistance generated by the NIC. The NIC was composed of an Op-Amp and resistors. The negative resistance was obtained with respect to a resistor connected in a feedback loop. The dimension of the Tx coil was $250mm{\times}250mm{\times}0.8mm$. The impedance and Q-factor were $31+j1874{\Omega}$ and 60, respectively. The negative resistance was selected to be $30{\Omega}$, and the Q-factor was increased to 900 by reduction of the transmitter resistance, which was about 15 times higher than that of a conventional transmitter. The measured PTE was greatly improved in comparison to that of a conventional system. These results demonstrate that the PTE is enhanced by using the NIC.

• The Korean Journal of Ecology
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• v.13 no.1
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• pp.33-50
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• 1990

The flora and vegetation of Jindo Archipelago were investigated from 1985 to 1989. In the area, 1089 species, 3 subspecies, 133 varieties, and 22 forma of vascular plants were recovered. From the data, the ecological characteristics such a value 1.39 in Pte-Q and Ch-$D_1-R_3$-e in biological type were recognized. Vegetation of the area is classified into 8 communities: Pinus thunbergii-, Quercus serrata-, Q. variabilis-, Carpinus coreana-, Prunus sargentii-, Camellia japonica-, Castanopsis cuspidata var. sieboldii and Q. acuta-community. The actual vegetation map was conducted with the materials obtained by the investigation of the vegetation in 103 area.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1061-1064
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• 2007

Thin Beam Excimer Laser Annealing is investigated as one possible process enabled by the variable concept of Thin Beam LTPS processing. The structure of the resulting p-Si material is analyzed in terms of grain size distribution, scaling with energy density and overlap, as well as average surface roughness. This process provides similar control and latitude as conventional excimer laser annealing, but reduced average surface roughness and the potential to be scaled to significant productivity levels.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.135-138
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• 1999

In this paper, we designed each matching networks by given input and output impedances of power amplifiers. Mearsured results for IMD and gain flatness are -30㏈c and $\pm$0.2㏈ with 38㏈m output power PEP of PTE10119 at 2.10-2.20㎓ and are -30㏈c and $\pm$0.4㏈ with 42㏈m output power PEP of MRF284 at same frequency range.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.19-29
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• 2007

This paper shares our project management experience in the 2 large-scale projects in managing a diverse international project team of consultants and managing in a foreign land. The first part introduces the two projects, second part addresses management of the projects and the last portion presents some of the challenges we experienced and highlights the importance of understanding the peculiarities of the operating environment, their norms, cultures, effectiveness and limitations of conventional project management tools while operating in a foreign country.

• Journal of Preventive Medicine and Public Health
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• v.53 no.4
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• pp.289-292
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• 2020

Yemen has been faced with the worst cholera epidemic of modern times, with more than 1 million suspected cases and 3000 deaths at the time of writing. This problem is largely due to the longstanding civil war between pro-government forces and the Houthi armed movement, which has severely damaged already vulnerable sanitation and healthcare facilities and systems in the country. It is further compounded by a dire lack of basic amenities, chronic malnutrition, and unfavourable weather conditions. Another contributory component may be aerial transfer by cholera-infected chironomid insects. To contain the spread of cholera in Yemen, a nation-wide armistice should be negotiated, and national and local committees must be convened to coordinate efforts on the ground. Community isolation facilities with proper sanitation, reliable disposal systems, and a clean water supply should be set up to isolate and treat sick patients. The continuity of vaccination programmes should be ensured. Public health campaigns to educate local communities about good hygiene practices and nutrition are also necessary. The One Health paradigm emphasizes a multi-sectoral and transdisciplinary understanding and approach to prevent and mitigate the threat of communicable diseases. This paradigm is highly applicable to the ongoing cholera crisis in Yemen, as it demands a holistic and whole-of-society approach at the local, regional, and national levels. The key stakeholders and warring parties in Yemen must work towards a lasting ceasefire during these trying times, especially given the extra burden from the mounting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak worldwide.

• Journal of Korean Neurosurgical Society
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• v.57 no.2
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• pp.77-81
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• 2015

Objective : The purpose of this study was to investigate changes in the plasma level of vascular endothelial growth factor (VEGF) after Gamma Knife radiosurgery (GKRS) for the treatment of meningioma. Methods : Fourteen patients with meningiomas had peripheral venous blood collected at the time of GKRS and at 1 week, 1 month, 3 month and 6 month visits. Plasma VEGF levels were measured using commercially available enzyme-linked immunosorbent assay. For controls, peripheral blood samples were obtained from 20 healthy volunteers. Results : The mean plasma VEGF level (29.6 pg/mL) in patients with meningiomas before GKRS was significantly lower than that of the control group (62.4 pg/mL, p=0.019). At 1 week after GKRS, the mean plasma VEGF levels decreased to 23.4 pg/mL, and dropped to 13.9 pg/mL at 1 month, 14.8 pg/mL at 3 months, then increased to 27.7 pg/mL at 6 months. Two patients (14.3%) with peritumoral edema (PTE) showed a level of VEGF 6 months after GKRS higher than their preradiosurgical level. There was no significant association found in an analysis of correlation between PTE and tumor size, marginal dose, age, and sex. Conclusion : Our study is first in demonstrating changes of plasma VEGF after stereotactic radiosurgery (SRS) for meningioma. This study may provide a stimulus for more work related to whether measurement of plasma level has a correlation with tumor response after SRS for meningioma.

• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.959-972
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• 2014

In this study, a space-time rainfall grid field generation model based on multifractal theory was verified using nine flood events in the upstream watershed of Chungju dam in South Korea. For this purpose, KMA radar rainfall data sets were analyzed for the space-time multifractal characteristics. Simulated rainfall fields that represent the multifractal characteristics of observed rainfall field were reproduced using the space-time rainfall grid field generation model with log-Poisson distribution and three-dimension wavelet function. Simulated rainfall fields were applied to the S-RAT model as input data and compared with both observed rainfall fields and low-resolution rainfall field runoff. Error analyses using RMSE, RRMSE, MAE, SS, NPE and PTE indicated that the peak discharge increases about 20.03% and the time to peak decreases about 0.81%.

• Archives of Plastic Surgery
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• v.45 no.4
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• pp.367-374
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• 2018

Background This analysis presents patient-reported outcomes of breast augmentation procedures performed in Singapore using an inframammary fold incision and the "5 Ps" best practice principles for breast augmentation. These data are the first of their kind in Southeast Asian patients. Methods Through a retrospective chart review, patients who underwent primary breast augmentation with anatomical form-stable silicone gel breast implants using an inframammary fold incision were followed for ${\geq}6$ months postoperatively. The BREAST-Q Augmentation Module (scores standardized to 0 [worst] - 100 [best]) and Patient and Observer Scar Assessment Scale (POSAS; 1 [normal skin] to 10 [worst scar imaginable]) were administered. Responses were summarized using descriptive statistics. Patient-reported events were collected. Results Twenty-two Southeast Asian patients (mean age, 35.1 years) completed ${\geq}1$ postoperative BREAST-Q and POSAS assessment and were assessed 11 months to 5.5 years postoperatively. The mean postoperative BREAST-Q satisfaction with breasts and psychosocial well-being scores were 69.2 and 84.0, respectively. The mean POSAS score for their overall opinion of the scar was 4.2; the mean scores for all scar characteristics ranged from 1.2 to 4.2. Over 90% of patients (20/22) said that they would recommend the procedure. Patient complaints following surgery included anisomastia (possibly pre-existing; n=2), sensory loss at the nipple (n=2) or around the nipple (n=3), scarring (n=4), and slight capsular contracture (n=1). No patients required reoperation. Conclusions Southeast Asian patients reported high long-term satisfaction scores on the BREAST-Q scale and with their scar characteristics following breast augmentation using an inframammary fold incision, and nearly all said they would recommend this procedure. No reoperations were necessary in patients assessed for up to 5.5 years postoperatively.