• Title/Summary/Keyword: An Chung Hwan

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Method of Estimate of Fracture Probability for Elastic-Plasticity by 2-Parameter Criterion (2-parameter criterion에 의한 탄소성 파괴확률 예측수법)

  • Kim, Tae-Sik;Yoon, Han-Yong;Lim, Myung-Hwan;Chung, Ui-Chung
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.226-234
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    • 2003
  • Put Many researcher have made much progress in studying an estimate for fracture probability of brittle materials. However, studies of the fracture probability for the elastic-plasticity have not been made yet. An estimate method for fracture probability which is grafted onto 2-parameter criterion and statistical probability analysis is not only introduced in this study, but also applied to the simple 2dimensional model and carbon steel piping to evaluate the effect of random variable.

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Scanner Certification Tool for the Standardization of Digitized Documents: Focusing on Target Factors and Measurement Programs

  • Park, Hyung-Ju;Har, Dong-Hwan
    • International Journal of Contents
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    • v.6 no.3
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    • pp.25-29
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    • 2010
  • Scanners play an important role in digitally reproducing the color and imaging of original documents used in public offices; however, the current system lacks a standard for digitized documents created by scanners, complicating efforts to create a digitized system. In particular, macrography cannot guarantee the accuracy and reliability of digitalized color documents, pictures, and photographs created by scanners. To this end, we develop a standardized evaluation tool and test target to certify digitalized documents created by a scanner in the domestic environment. In this study, we enhance the accuracy and reliability of scanned data to create an advanced standard evaluation tool for scanners. Moreover, to produce a scanner certification standard, we overcome existing problems related to the growing market. We anticipate that this new standard will see a high degree of application in the current environment.

General Public Knowledge Regarding Topical Corticosteroids: A Nationwide Survey in South Korea

  • Seo, Heenam;Song, Seoung Yeon;Kim, Dahye;Park, Ji Hwan;Shin, Yoonho;Lee, Kang Hyuk;Choi, Soo An;Lee, Ju-Yeun;Kim, Do Young;Shin, Wan Gyoon;Kim, Eunyoung
    • Korean Journal of Clinical Pharmacy
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    • v.32 no.2
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    • pp.84-92
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    • 2022
  • Background: Topical corticosteroids (TCs) are available both as over-the-counter drugs and prescription medicines at pharmacies. Although they are generally safe drugs, inappropriate and excessive use could result in potential side effects. Thus, it is important to have appropriate knowledge regarding the use of TCs. We performed a cross-sectional survey to assess public knowledge and the potential misuse or overuse of TCs. Methods: A cross-sectional and nationwide online survey was conducted among participants who were aware of TCs. The survey items included sources of information, indications, potential side effects, and methods of application of TCs. A comparative analysis was conducted between those with (TC users) and without (TC non-users) an experience of using TCs. Results: Among 3,000 participants, 74.4% were TC users. The mass media was the most common information source of TCs, and only one-third of the surveyed people relied on pharmacists or doctors for information. Regarding indications and application methods, incorrect answer rate was high in some items, but respondents showed adequate knowledge. However, awareness of the safety of TCs was low. Overall, the TC users showed a higher knowledge of TCs than TC non-users. Conclusions: Public knowledge of the use of TCs appears to be appropriate. However, we found potential misuse or overuse of some items and a lack of awareness of the side effects concerning TCs. Thus, healthcare professionals' significant role is required.

Investigation of Power Saving Efficiency for the OFDM Based Multimedia Communication Terminal (OFDM 기반 광대역 멀티미디어 단말의 전력절감 효율 분석에 관한 연구)

  • Moon, Jae-Pil;Lee, Eun-Seo;Kim, Dong-Hwan;Lee, Jae-Sik;Chang, Tae-Gyu
    • Proceedings of the IEEK Conference
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    • 2005.11a
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    • pp.155-158
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    • 2005
  • An invesitigation on power consumption of a mobile multimedia system using OFDM and MDVS technique is reported here. Analysis and simulation are performed to find the significances of proposed Microscopic Dynamic Voltage Scaling(MDVS) tehnique[4] on digital processor in terms of power saving. A study is also made to show power reduction in mobile multimedia system by incorporating OFDM modulation scheme in RF front-end. Finally, overall power consumption by functionally distinguished blocks ie. RF front-end, digital processor and human interface unit is shown here. Total power consumption is 8.2W for 2Mbps SD-quality WCDMA multimedia video service - the power consumption of digital processor is 3.9W(48%), the power consumption of RF front-end is 3.2W (36%), and the power consumption of interface is 1.8W(16%). Power saving of applying purposed MDVS technique is 35% in digital processor, and power saving of OFDM technique is 10-12dB in RF front-end.

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Ecological Characteristics and Distribution of Plant Resources of Pyrus and Malus sp. in Jindong Valley, Gangwon Province

  • Ahn, Young-Hee;Chung, Kyu-Hwan;Choi, Kwang-Yool;Park, Dae-Sik
    • Plant Resources
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    • v.4 no.3
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    • pp.130-139
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    • 2001
  • Four major naturally populated areas around the Jindong valley in Inje-Gun, Gangwon province for wild Pyrus ussuriensis, Malus sieboldii, and Malus baccata are mostly located on the southeast side of the mountains at 630-745m in altitude at sea level and are in very good sunny areas. The total of 77 taxa dividing into 32 families, 58 genera, 65 species, and 12 varieties has been inhabited in these areas. Most of these plants are heliophytes, which love sunshine, but some of rhizo-plants such as Sasa borealis, climbing plants such as Actinidia arguta and Celastrus orbiculatus, or naturalized plants like Bidens frondosa are also shown. These areas have been continually destroyed, so it is possibly thought that the second transition has been progressed. The index of species diversity of plant groups in these areas is 0.672∼1.465 based on the Shannon-Wiener's method, but its index for the area that rhizo-plants like Sasa borealis are growing as an under planting decreases relatively. In this study, the oldest plant of Pyrus ussuriensis in Korea, which is 120cm in diameter at breast height (DBH), 19m in tree height and 25m in width, has been found.

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Histologic features and predicting prognosis in ulcerative colitis patients with mild endoscopic activity

  • Seung Yong Shin;Hee Sung Kim;Kisung Kim;Chang Won Choi;Jung Min Moon;Jeong Wook Kim;Hyun Jin Joo;Jeongkuk Seo;Muhyeon Sung;Chang Hwan Choi
    • The Korean journal of internal medicine
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    • v.39 no.1
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    • pp.68-76
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    • 2024
  • Background/Aims: We aimed to evaluate the histologic features predictive of prognosis and correlate them with endoscopic findings in patients with ulcerative colitis (UC) having complete or partial mucosal healing (MH). Methods: We prospectively collected and reviewed data from patients with UC who underwent colonoscopy or sigmoidoscopy with biopsy. Complete and partial MH were defined as Mayo endoscopic subscores (MESs) of 0 and 1, respectively. Histologic variables, including the Nancy index (NI), predicting disease progression (defined as the need for medication upgrade or hospitalization/surgery), were evaluated and correlated with endoscopic findings. Results: Overall, 441 biopsy specimens were collected from 194 patients. The average follow-up duration was 14.7 ± 7.4 months. There were 49 (25.3%) and 68 (35.1%) patients with MESs of 0 and 1, respectively. Disease progression occurred only in patients with an MES of 1. NI ≥ 3 was significantly correlated with disease progression during follow-up. Mucosal friability on endoscopy was significantly correlated with NI ≥ 3 (61.1% in NI < 3 vs. 88.0% in NI ≥ 3; p = 0.013). Conclusions: Histological activity can help predict the prognosis of patients with UC with mild endoscopic activity. Mucosal friability observed on endoscopy may reflect a more severe histological status, which can be a risk factor for disease progression.

Assessment of CUPID code used for condensation heat transfer analysis under steam-air mixture conditions

  • Ji-Hwan Hwang;Jungjin Bang;Dong-Wook Jerng
    • Nuclear Engineering and Technology
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    • v.55 no.4
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    • pp.1400-1409
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    • 2023
  • In this study, three condensation models of the CUPID code, i.e., the resolved boundary layer approach (RBLA), heat and mass transfer analogy (HMTA) model, and an empirical correlation, were tested and validated against the COPAIN and CAU tests. An improvement on HMTA model was also made to use well-known heat transfer correlations and to take geometrical effect into consideration. The RBLA was a best option for simulating the COPAIN test, having mean relative error (MRE) about 0.072, followed by the modified HMTA model (MRE about 0.18). On the other hand, benchmark against CAU test (under natural convection and occurred on a slender tube) indicated that the modified HMTA model had better accuracy (MRE about 0.149) than the RBLA (MRE about 0.314). The HMTA model with wall function and the empirical correlation underestimated significantly, having MRE about 0.787 and 0.55 respectively. When using the HMTA model, consideration of geometrical effect such as tube curvature was essential; ignoring such effect leads to significant underestimation. The HMTA and the empirical correlation required significantly less computational resources than the RBLA model. Considering that the HMTA model was reasonable accurate, it may be preferable for large-scale simulations of containment.

Effects of Mg Suppressor Layer on the InZnSnO Thin-Film Transistors

  • Song, Chang-Woo;Kim, Kyung-Hyun;Yang, Ji-Woong;Kim, Dae-Hwan;Choi, Yong-Jin;Hong, Chan-Hwa;Shin, Jae-Heon;Kwon, Hyuck-In;Song, Sang-Hun;Cheong, Woo-Seok
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.2
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    • pp.198-203
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    • 2016
  • We investigate the effects of magnesium (Mg) suppressor layer on the electrical performances and stabilities of amorphous indium-zinc-tin-oxide (a-ITZO) thin-film transistors (TFTs). Compared to the ITZO TFT without a Mg suppressor layer, the ITZO:Mg TFT exhibits slightly smaller field-effect mobility and much reduced subthreshold slope. The ITZO:Mg TFT shows improved electrical stabilities compared to the ITZO TFT under both positive-bias and negative-bias-illumination stresses. From the X-ray photoelectron spectroscopy O1s spectra with fitted curves for ITZO and ITZO:Mg films, we observe that Mg doping contributes to an enhancement of the oxygen bond without oxygen vacancy and a reduction of the oxygen bonds with oxygen vacancies. This result shows that the Mg can be an effective suppressor in a-ITZO TFTs.

The plan of stabilizing Gyeongnam Chung-yang Green Pepper Farm Income (경남 청양 풋고추농가 소득 안정화 방안)

  • Hwang, Min-Ji;Jeong, Ho-Jung;Cho, Jae-Hwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.2
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    • pp.387-396
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    • 2018
  • This study examined the instability factor of real income and net profits of Chung-yang Green Pepper Farm through an analysis of the operating costs. Furthermore, this paper suggests a plan for stabilizing the price by shipment adjustments resulting from an analysis of the price elasticity by A Linear Approximated Inverse Almost Ideal Demand System (LA/IAIDS). The income instability factor of the farm based on an analysis of the operating costs was attributed to the unexpected loading of utility expenses and collapse of the price due to oversupply at a specific point in time. On the other hand, this is insufficient to completely explain the income instability factor of Chung-yang Green Pepper Farm because a price collapse does not include the monthly price changes. An analysis of the price and scale flexibility of Chung-yang Green Pepper Farm by monthly data showed that annual farm net yield increases by 1.21% due to a 2.21% increase in price if the shipment quantity is reduced to 1% a year. In summary, a plan that supports the farm price received through declining shipments in winter is effective in stabilizing the income of farms. Because Chung-yang Green Pepper in Gyeongnam region has an especially high market share of 82.5%, the prices and income of Gyeongnam Chung-yang Green Pepper farms can be stabilized effectively if they form an association of producers around the Gyeongnam region and adjust the shipment.

Characteristics of Photoresist-derived Carbon Nanofibers for Li-ion Full Cell Electrode

  • Kim, Hwan-Jun;Joo, Young-Hee;Lee, Sang-Min;Kim, Chang-Il
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.5
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    • pp.265-269
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    • 2014
  • Carbon nanofiber electrode has been fabricated for energy storage systems by the electrospinning of SU-8 precursor and subsequent pyrolysis. Various parameters including the applied voltage, the distance between syringe tip and target collector and the flow rate of the polymer affect the diameter of SU-8 electrospun nanofibers. Shrinkage during pyrolysis decreases the fiber diameter. As the pyrolysis temperature increases, the resistivity decreases dramatically. Low resistivity is one of the important characteristics of the electrodes of an energy storage device. Given the advantages of carbon nanofibers having high external surface area, electrical conductivity, and lithium intercalation ability, SU-8 derived carbon nanofibers were applied to the anode of a full lithium ion cell. In this paper, we studied the physical properties of carbon fiber electrode by scanning transmission microscopy, thermal gravimetric analysis, and four-point probe. The electrochemical characteristics of the electrode were investigated by cyclic voltammogram and electrochemical impedance spectroscopy plots.