• Journal of Korean Foot and Ankle Society
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• v.19 no.2
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• pp.51-57
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• 2015

Purpose: Minimal incision distal metatarsal osteotomy (MIDMO) is known to be an effective surgical procedure for mild to moderate hallux valgus. However, the result of MIDMO on moderate to severe hallux valgus is controversial; therefore, we investigated the radiological and clinical results of MIDMO on moderate to severe hallux valgus. Materials and Methods: We reviewed 51 feet (48 patients) with moderate to severe hallux valgus. The mean age was 67.0 years and the mean follow-up period was 32.2 months. Radiological data of hallux valgus angle, first intermetatarsal angle, and distal metatarsal articular angle on plain radiographs were analyzed. Recurrence, union, lateral translation of distal fragment and angulation were also analyzed. The clinical data were obtained using American Orthopaedic Foot and Ankle Society (AOFAS) score of preoperation and last follow-up. Receiver operating characteristic (ROC) curve was used to determine a cut-off value. Results: The mean hallux valgus angle measured at preoperation was $37.7^{\circ}$ and $15.9^{\circ}$ at last follow-up. The mean first intermetatarsal angle of preoperation and last follow-up were $15.2^{\circ}$ and $8.3^{\circ}$. The mean distal metatarsal articular angle changed from $12.6^{\circ}$ at preoperation to $7.8^{\circ}$ at last follow-up. Preoperative hallux valgus angle (p=0.0051) and distal metatarsal articular angle (p=0.0078) were statistically significant factors affecting postoperative AOFAS score. Cut-off value of each was $37^{\circ}$ and 13o, respectively. Lateral translation of distal fragment in 5 recurrent cases was 23.0% compared to 45.3% of 46 non-recurrent cases. The result was statistically significant and the cut-off value was 38%. Conclusion: Sufficient lateral translation over 38% in MIDMO on moderate to severe hallux valgus patients with preoperative hallux valgus angle under $37^{\circ}$ and distal metatarsal articular angle under $13^{\circ}$ can lead to good clinical results without recurrence.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.723-730
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• 2018

Objective : The aim of the present study was to identify whether the deformity angular ratio (DAR) influences the occurrence of complications after posterior vertebral column resection (PVCR) and to establish the DAR cut-off value. Methods : Thirty-six consecutive patients undergoing PVCR from December 2010 to October 2016 were reviewed. The relationships between the total, sagittal, and coronal DAR and complications were assessed using receiver operator characteristics curves. The patients were divided into two groups according to a reference value based on the cut-off value of DAR. Demographic, surgical, radiological, and clinical outcomes were compared between the groups. Results : There were no significant differences in the patient demographic and surgical data between the groups. The cut-off values for the total DAR (T-DAR) and the sagittal DAR (S-DAR) were 20.2 and 16.4, respectively (p=0.018 and 0.010). Both values were significantly associated with complications (p=0.016 and 0.005). In the higher T-DAR group, total complications (12 vs. 21, p=0.042) and late-onset complications (3 vs. 9, p=0.036) were significantly correlated with the T-DAR. The number of patients experiencing complications (9 vs. 11, p=0.029) and the total number of complications (13 vs. 20, p=0.015) were significantly correlated with the S-DAR. Worsening intraoperative neurophysiologic monitoring was more frequent in the higher T-DAR group (2 vs. 4) than in the higher S-DAR group (3 vs. 3). There was no difference in neurological deterioration between the groups after surgery. Conclusion : Both the T-DAR and the S-DAR are risk factors for complications after PVCR. Those who had a T-DAR >20.2 or S-DAR >16.4 experienced a higher rate of complications after PVCR.

• Journal of Appropriate Technology
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• v.5 no.2
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• pp.62-69
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• 2019

Supplying stable electric power is one of the important objectives of the Official Development Assistance (ODA) because it is strongly related with improving living standards and income levels in the region. However, rural areas in many developing countries are not properly connected to national power grids, and even areas connected to national power grids are frequently blacked out due to limitations in power capacity. These lack of electric power is a major obstacle to improving income levels and improving living standards in those areas. The Korea-Tanzania Innovative and Energy Center (iTEC), which was established by Seoul National University in cooperation with the Nelson-Mandela Africa Institute of Science and Technology and Technology (NM-AIST) try to build a small solar power plant using a smart-off grid in rural area of Tanzania, where there is no electricity. 10 kW and 7 kW solar power plants are built in Mkalama Village in Kilimanajaro Region and Ngurdoto Village in Arusha Region to provide power to about 50 households each. In addition, smart monitoring systems were installed to collect data about status of power system and power consumption of each house. iTEC seeks for sustainable improvement the income level and quality of life of rural residents in developing countries through the construction of small solar power plants using smart-off grid, and the implementation of various connected projects.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.603-610
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• 2011

The long jump motions of 8 finalists in the women's long jump at the IAAF World Championships, Daegu 2011 were analyzed, and the kinematic characteristics of their techniques were investigated. The kinematic characteristics of the long jump motion of the 8 finalists were as follows. In the run-up phase, the length of the 2 stride was $108{\pm}6.92%$ that of the 3 stride. The length of the 1 stride was $91{\pm}5.78%$ that of the 2 stride. The change in the height of the center of gravity was $0.07{\pm}0.03$ m. The maximum velocity during the run-up phase was $9.44{\pm}0.13$ m at the 1 stride. In the take-off phase, the horizontal velocity, vertical velocity, reduction in horizontal velocity were $7.80{\pm}0.15$ m/s, $2.96{\pm}0.14$ m/s, and $1.64{\pm}0.19$ m/s, respectively. The minimum knee angle and take-off angle were $151{\pm}8.89^{\circ}$ and $20.7{\pm}1.03^{\circ}$, respectively. In the flight phase, the flight time and maximum height of the center of gravity were $0.78{\pm}0.03$ s, and $1.60{\pm}0.05$ m, respectively. In the landing phase, the landing length was $0.50{\pm}0.07$ m. The trunk angle, knee angle, and hip angle were $74{\pm}18.75^{\circ}$, $131{\pm}10.45^{\circ}$, and $82{\pm}9.03^{\circ}$, respectively. The kinematic characteristics of the motion of a good long jump were as follows. The reduction in the horizontal velocity in the take-off phase was minimized, and the maximum velocity of the run-up was maintained. The vertical velocity in the take-off phase was increased using a rapidly extended knee and high center of gravity.

• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.435-441
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• 2008

In this paper, we investigated the electrical properties of triisopropylsilyl (TIPS) pentacene organic thin-film transistor (OTFT) depending on solvent type. We spin coated TIPS pentacene by using chlorobenzene, p-xylene, chloroform, and toluene as solvents. Fabricated OTFT with chlorobenzene shows field-effect mobility of $1.0{\times}10^{-2}cm^2/V{\cdot}s$, on/off ratio of $4.3{\times}10^3$ and threshold voltage of 5.5 V. In contrast, with chloroform, the mobility is $5.8{\times}10^{-7}cm^2/V{\cdot}s$, on/off ratio of $1.1{\times}10^2$ and threshold voltage of 1.7 V. Moreover we measured the grain size of each TIPS pentacene solvent by atomic force microscopy (AFM). From these results, it can be concluded that a solvent with higher boiling point results in better electrical characteristics due to large grain size and high crystallinity of TIPS pentacene layer. In this paper TIPS pentacene with chlorobenzene shows the best electrical properties.

• Journal of Korean Society on Water Environment
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• v.37 no.5
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• pp.381-397
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• 2021

Off-flavor materials (geosmin and 2-methylisoborneol (2-MIB)) produced by microorganisms, such as, cyanobacteria and actinomycetes, cause freshwater use problems worldwide. Due to unpleasant taste and odor, these microorganisms have raised issues especially in drinking water resources. Recently, there has been increasing concern about 2-MIB and causal cyanobacteria, namely, Pseudanabaena, in Korea. However, material production and ecological dynamics remain largely unexplored. This study reviewed the distribution of Pseudanabaena, its species diversity, and the research trend of molecular ecology related to 2-MIB production in Korea. Based on published literature, we found that seven species of Pseudanabaena which include P. mucicola, P. limnetica, P. redekei, P. catenata, P. galeata, P. yagii, and P. cinerea appeared to occur in a variety of Korean water systems. All of these Pseudanabaena species were found in the North-Han River system (Lakes Soyang, Chuncheon, Uiam, and Paldang). Some of these species were also detected in other watersheds, but the precise species diversity was not identified. Species belonging to the Pseudanabaena genus are hard to classify through general microscopic alpha taxonomy, due to their very small cell size and similar morphological characters. Moreover, the potential of 2-MIB production cannot be detected by microscopic observation. Combining molecular ecological techniques, such as, environmental genomic materials (eDNA, eRNA) analyses to conventional methods could be useful to better understand the off-flavor material production and dynamics, thereby providing more efficient management strategies of freshwater systems.

• Tunnel and Underground Space
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• v.32 no.5
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• pp.285-297
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• 2022

We report results of Extended Leak-Off Test (XLOT) conducted in a large diameter borehole, which is drilled for installation of deep borehole geophysical monitoring system to monitor micro-earthquakes and fault behavior of major fault zones in the southeastern Korean Peninsula. The borehole was planned to secure a final diameter of 200 mm (or more) at a depth of ~1 km, with 12" diameter wellbore to intermediate depths, and 7-7/8" (~200 mm) to the bottom hole depth. We drilled first the 12" borehole to approximately 504 m deep and installed American Petroleum Institute standard 8-5/8" casing, then annulus between the casing and bedrock was fully cemented. XLOT was carried out for several purposes such as confirming casing and cementing integrity, measuring rock stress states. To that end, we drilled additional 4 m long open hole interval to directly inject water and pressurize into the rock mass using the upper API casings. During the XLOT, flow rates and interval pressures were recorded in real time. Based on the logs we tried to analyze hydraulic conductivity of the test interval.

• 대한예방의학회:학술대회논문집
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• 2005.10a
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• pp.302-302
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• 2005

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.145-148
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• 2007

The authors report on the fabrication of thin film transistors (TFTs) that use amorphous indium-gallium-zinc oxide (a-IGZO) channel and have the channel length (L) and width (W) patterned by dry etching. To prevent the plasma damage of active channel, a 100-nm-thckness $SiO_{x}$ by PECVD was adopted as an etch-stopper structure. IGZO TFT (W/L=10/50${\mu}m$) fabricated on glass exhibited the high performance mobility of $35.8\;cm^2/Vs$, a subthreshold gate voltage swing of $0.59V/dec$, and $I_{on/off}$ of $4.9{\times}10^6$. In addition, 4.1” transparent QCIF active-matrix organic light-emitting diode display were successfully fabricated, which was driven by a-IGZO TFTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.410-410
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• 2012

The continuous monolayer graphene was synthesized on electro-polished copper foil. Electro-polishing sticks off the coating layer of copper foil, which prevents the continuous graphene growth. The quality of continuous graphene is dependent on roughness of copper foil. Copper foil roughness could be controlled by changing polishing condition. The effects of working voltage (4-6 V) and time (30-70 sec) for electro-polishing were systematically examined. The change of surface roughness was checked with AFM.