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Development of a Tractor Attached TMR Mixer(II) -Modification of TMR mixer and its performance test- (트랙트 견인형 TMR 배합기의 개발(II) -TMR 배합기의 수정 개발 및 성능시험-)

  • Park, K. K.;Koo, Y. M.;Kim, H. J.;Seo, S. H.;Jang, C.;Nah, K. D.;Hong, D. H.;Lee, J. S.
    • Journal of Biosystems Engineering
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    • v.25 no.4
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    • pp.257-264
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    • 2000
  • A tractor attached TMR(model 430) mixer has been developed in a previous study. However, the mixer was found to be improved through field applications in its capacity, manufacturing cost, ergonomic design and power-train requirement. The TMR mixer was modified into a model TMR500, approved by Institute of Agricultural Mechanization, as follows : 1. Roughage cutting system was seperated from the mixer, resulting in the 33% reduction of manufacturing cost. 2. Enlarged hopper capacity enabled to feed 60 heads at a batch. 3. Hydraulically controlled gate system saved ergonomic man power. 4. Power transmission system was changed from a chain-sprocket system(27:1) to the gear-train reduction system(38.6:1) to satisfy the recommended use of 540rpm PTO input.

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A Case Report on the Clearance of Vancomycin-Resistant Enterococcus Colonization in a Patient with Traumatic Subarachnoid Hemorrhage and Subdural Hematoma Treated with Hwanglyeonhaedok-tang (황련해독탕 투여 후 Vancomycin-resistant Enterococcus 집락이 해제된 외상성 지주막하출혈 및 경막하혈종 환자 증례보고 1례)

  • Chae, Han-nah;Lee, Ji-eun;Shim, Sang-song;Shin, Sun-ho;Shin, Yong-jeen
    • The Journal of Internal Korean Medicine
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    • v.41 no.3
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    • pp.502-507
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    • 2020
  • This study aimed to investigate the effect of Hwanglyeonhaedok-tang on the clearance of vancomycin-resistant Enterococcus (VRE) colonization in a patient with traumatic subarachnoid hemorrhage and subdural hematoma. A 73-year-old man who was diagnosed with traumatic subarachnoid hemorrhage and subdural hematoma with isolation of VRE colonization was administered Hwanglyeonhaedok-tang and followed up with a rectal swab VRE culture every week. After treatment with Hwanglyeonhaedok-tang, VRE colonization was no longer detected. This case report proved that Hwanglyeonhaedok-tang could be an effective treatment for clearance of VRE colonization in a patient with traumatic subarachnoid hemorrhage and subdural hematoma.

Effect of Blade Materials on Wear Behaviors of Styrene-Butadiene Rubber and Butadiene Rubber

  • Lee, Gi-Bbeum;Shin, Beomsu;Han, Eunjung;Kang, Dawon;An, Dae Joon;Nah, Changwoon
    • Elastomers and Composites
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    • v.56 no.3
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    • pp.172-178
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    • 2021
  • The wear behavior of styrene-butadiene rubber (SBR) and butadiene rubber (BR) was investigated using a blade-type abrader with a steel blade (SB), Ti-coated tungsten carbide blade (TiB), or zirconia blade (ZB). The wear rate of SBR against SB and TiB decreased with increasing number of revolutions because of the blunting of the blades during wear. However, the wear rate of SBR against ZB remained nearly constant with little blade blunting. Generally, the wear rate of BR was largely unaffected by the blade material used for abrasion. The wear rate and frictional coefficient of SBR were found to be higher than those of BR at similar levels of frictional energy input. A power-law relationship was found between the wear rate and frictional energy input during abrasion. A well-known Schallamach pattern was observed for SBR, while a much finer pattern was observed for BR. The blade material affects the wear rate of the rubbers because the macromolecular free radicals and blade tend to undergo mechano-chemical reactions. The inorganic ZB was found to be the most inert for such a mechanism.

Laser-induced Graphene Based Wearable Glucose Patch Sensor with Ultra-low Detection Limit (레이저 유도 그래핀 기반의 고성능 웨어러블 포도당 패치센서)

  • Nah, Joongsan;Yoon, Hyosang;Xuan, Xing;Kim, Jiyoung;Park, Jaeyeong
    • Journal of Sensor Science and Technology
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    • v.28 no.1
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    • pp.47-51
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    • 2019
  • Sweat-based glucose sensors are being widely investigated and researched as they facilitate painless and continuous measurement. However, because the concentration of sweat glucose is almost a hundred times lower than that of blood glucose, it is important to develop electrochemical sensing electrode materials that are highly sensitive to glucose molecules for the detection of low concentrations of glucose. The preparation of a flexible and ultra-sensitive sensor for detection of sweat glucose is presented in this study. Oxygen and nitrogen are removed from the surface of a polyimide film by exposure to a CO2 laser; hence, laser-induced graphene (LIG) is formed. The fabricated LIG electrode showed favorable properties of high roughness and good stability, flexibility, and conductivity. After the laser scanning, Pt nanoparticles (PtNP) with good catalytic behavior were electrodeposited and the glucose sensor thus developed, with a LIG/PtNP hybrid electrode, exhibited a high order of sensitivity and detection limit for sweat glucose.

Technological Trends in a local anodization (국부적 양극산화 기술 동향)

  • Kwang-Mo Kang;Sumin Choi;Yoon-Chae Nah
    • Journal of the Korean institute of surface engineering
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    • v.56 no.2
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    • pp.115-124
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    • 2023
  • Anodization is an electrochemical process that electrochemically converts a metal surface into an oxide layer, resulting in enhanced corrosion resistance, wear resistance, and improved aesthetic appearance. Local anodization, also known as selective anodization, is a modified process that enables specific regions or patterns on the metal surface to undergo anodization instead of the entire surface. Several methods have been attempted to produce oxide layers via localized anodic oxidation, such as using a mask or pre-patterned substrate. However, these methods are often intricate, time-consuming, and costly. Conversely, the direct writing or patterning approach is a more straightforward and efficient way to fabricate the oxide layers. This review paper intends to enhance our comprehension of local anodization and its potential applications in various fields, including the development of nanotechnologies. The application of anodization is promising in surface engineering, where the anodic oxide layer serves as a protective coating for metals or modifies the surface properties of materials. Furthermore, anodic oxidation can create micro- and nano-scale patterns on metal surfaces. Overall, the development of efficient and cost-effective anodic oxidation methods is essential for the advancement of various industries and technologies.

On Some Changes in Polymer Blend Topological and Molecular Structures Resulted from Processing

  • Jurkowski, B.;Jurkowska, B.;Nah, C.
    • Elastomers and Composites
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    • v.37 no.4
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    • pp.234-243
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    • 2002
  • A general scheme of a rubber structure is proposed. Using the thermomechanical method(TMA), some changes in the molecular and topological structures for uncured and cured, and unfilled and filled rubbers during processing are shown. In our investigations as region it is understood a complex structure, which is expressed at the thermomechanical curve(TMC) as a zone differed from others in thermal expansion properties. This zone is between the noticed temperatures of relaxation transitions, usually on the level like those determined by DMTA at 1Hz. These regions, which shares, are not stable, and differ in molecular-weight distribution(MWD) of chain fragments between the junctions. Differences in dynamics of the formation of the molecular and topological structures of a vulcanizate are dependent on the rubber formulation, mixing technology and curing time. Some of characteristics of these regions correlate with mechanical properties of vulcanizates what is shown for NR rubbers containing ENR or CPE as a polymeric additive. It is well known that the state of order influences diffusivity of low-molecular substances into the polymer matrix. Because of this, the two topological amorphous regions should influence the distribution of the ingredients and resulting in rubber compounds' heterogeneity, and related properties of cured rubber. Investigation of this problem is expected to be, in the future, one of the essential factors in determining further improvement of polymeric materials properties by compounding with additives and in reprocessing of rubber scrap.

A Study on the Effect of Customer Satisfaction and Switching Cost on Continuous Use Intention: Focusing on Dental Hospitals and Clinics (고객만족과 전환비용이 지속적 이용의도에 미치는 영향에 관한 연구 : 치과 병.의원을 중심으로)

  • Byun, Jung-A;Nah, Yul;Kim, Yang-Kyun
    • Korea Journal of Hospital Management
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    • v.17 no.2
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    • pp.52-72
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    • 2012
  • In this study, we examined the effect of customer satisfaction and switching cost on continuous use intention to suggest how organizations can retain their customers when market growth slows down and competition becomes stronger. We carefully developed and modified survey instruments through a pre-test, and subsequently surveyed 432 dental care users in Seoul and Busan areas. As a result of regression analysis, higher procedural learning switching cost, relational switching cost, and customer satisfaction were manifested in the increased continuous use intention. In contrast, higher financial switching cost and customer satisfaction with insufficient effort for information acquisition led to decreased switching intention. In addition, procedural initial switching cost and residents in Seoul led to increased switching intention. Understanding continuous use intention and switching intention is important for healthcare institutions striving to maintain market position. The findings of this study suggest a paradigm shift from conventional transactional marketing to strategic relational marketing to be effective in the healthcare environment today.

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Lymphangioma of the Head and Neck: Report of 4 Cases (두경부 림프관종의 증례보고)

  • Jeong Yeon-Hwa;Cho Bong-Hae;Nah Kyung-Soo
    • Imaging Science in Dentistry
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    • v.30 no.1
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    • pp.87-91
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    • 2000
  • Lymphangiomas are uncommon benign congenital tumors. Most occur in the head and neck and most lesions present by the age of 2 years. We present our experience with four patients who have lymphangiomas of the head and neck with tongue involvement. First case is a 7-year-old male who has the cystic lymphangioma of left submandibular area. Second a 22-year-old female has a lesion involving the border of right tongue. Third case is the lymphangioma which occurs in the right upper lip of a 6-year old male. The last patient is a 28-year old male who fell down and whose right face was swollen up. He had undergone an operation and been treated with steroid before. The characteristic appearances of imaging methods were described and all lesions best depicted on T2-weighted images. Our experience indicates that MRI is useful in the diagnosis and treatment planning of lymphangioma.

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Development of Anti-fluttering Tilting Pad Journal Bearing with the Shape Modification of Upper Pad (상부패드의 형상 변경을 통한 'Anti-fluttering 틸팅패드 저널베어링' 개발)

  • Yang Seong-Heon;Nah Un-Hak;Park Heui-Joo;Kim Chae-Sil
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.796-805
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    • 2005
  • The tilting pad journal bearings have been widely used to support high pressure/high rotating turbine rotors owing to their inherent dynamic stability characteristics. However, fatigue damages in the upper unloaded pads and the break of locking pins etc. by pad fluttering are continuously taken place in the actual steam turbines. The purpose of this paper is to develop a new bearing model that can prevent bearing problems effectively by pad fluttering in a tilting pad journal bearing. A new bearing model which has a wedged groove is suggested from the studies of fluttering mechanism performed by previously research works. The fluttering characteristics of the upper unloaded pad are studied experimentally in order to verify the reliability of a new bearing model. It can be known that the phenomenon of pad fluttering nearly does not occurred in the new bearing model under the various experimental conditions. And it is observed that any kinds of bearing failures by pad fluttering does not detect in the application of acture steam turbines.

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Diagnosis of Fault and Abnormal Conditions in a Single-Phase Transformer Using S-parameter Measurement (S파라미터를 이용한 단상 변압기의 이상 상태 진단에 대한 연구)

  • Kim, Jeongeun;Kim, Kwangho;Nah, Wansoo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.10
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    • pp.1344-1352
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    • 2018
  • In this paper, we propose a two-port S-parameter data to diagnose the fault conditions of a single-phase transformer. Using the S-parameters we can measure the reflection and transmission characteristics of signal power at the port of a transformer, which can also be converted into ABCD parameters and Z parameters through a well-known conversion formulas. Transformer fault diagnoses can be performed based on the intuitive and qualitative/quantitative characteristics of the these parameters. In addition, we can obtain wide frequency characteristics at the primary and secondary sides of the transformer, which can be used to get time domain responses using the inverse Fourier transformation with some specific input waveform. In order to verify the effectiveness of the proposed method, the fault conditions were analyzed in simulation and experiment for 3 kVA single phase transformer with 15: 5 turns ratio, and the validity of the proposed method was verified.