• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.35-41
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• 2004

The yeongok stream originates at the natural park, Mt. O-dae and flows to the East Sea of korea, normally maintaining I or II grade of water quality and its average water flux is 352,100 ㎥/d. However, the typhoon 'Rusa', which occured on 31 August 2002, changed its watercourse and configuration, and the ecosystem was deeply damaged. Moreover, the hydrological characteristics were once more transformed, and the ecosystem was secondarily damaged during repair-work of destroyed bridges and elevations. After the flood disaster, the species diversity diminished 17% for attached diatom and 44% for aquatic animals. However, the earth and sand, dug from river bed during intensive repair-work throughout the entire stream, made diversity drop to 32% for the diatom and the aquatic animals were wiped out. Especially, fishes were totally destroyed except for some species such as Moroco oxycephalus in the upper stream. The yeongok stream has little contamination source and short water residence time due to the short length and rapid slope, and consequently a temporary deterioration of water quality caused by repair-work may be rapidly recovered, but it needs a long time to restore the damaged ecosystem.

• Journal of Korean Neurosurgical Society
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• v.29 no.10
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• pp.1365-1371
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• 2000

Objectives : Spinal cord compression is a rare presentation of non-Hodgkin's lymphoma(NHL), occurring in 0.1% to 10.2% of patients. Primary spinal extradural NHL, i.e. occurring in the absence of any detectable extraspinal lymphoproliferative disorder, has a potentially favourable outcome if diagnosed and treated early. The authors describe two patients with a clinical picture of acute spinal cord compression as the first presentation of NHL. Methods : The patients were 48-year-old female and 27-year-old female. Both presented with back pain followed by acute paraparesis and voiding difficulty. One patient was diabetic. Plain radiographs of the spine were not specific. Thoracic spine magnetic resonance imaging(MRI) revealed evidence of extradural soft tissue mass extending multiple vertebral segments. Results : The patients underwent emergency laminectomy for decompression and tissue diagnosis. Histological and immunohistochemical study revealed B-cell lymphoma, intermediate grade in both patients. Postoperative staging did not reveal any additional lesions other than extradural manifestation of the malignant lymphoma. Surgery with additional chemotherapy and radiotherapy allowed the clinical improvement of both patients. Conclusion : The authors report two patients with a clinical picture of acute spinal cord compression as the first presentation of NHL, and stress that primary spinal epidural NHL should be a diagnostic consideration in the patient without prior history of malignancy who presents with a prodrome of back pain followed by a rapid neurological deterioration.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.124-139
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• 2007

In order to obtain the maximum flame retardancy with the minimal deterioration of physical properties of PU flame-retardant coatings, chlorine and phosphorous functional groups were introduced into the pre-polymer of modified polyesters. In the first step, the tetramethylene bis(orthophosphate) (TBOP) and neohexanediol dichloroacetate (DCA-adduct) intermediates were synthesized. In the second step, 1,4-butanediol and adipic acid monomers were polymerized with the two kind of intermediates to obtain copolymer. The modified polyesters containing chlorine and phosphorous (ATBA-10C, -20C, and -30C) were synthesized by adjusting the contents of chlorine compound (dichloroacetic acid, 10, 20, 30 wt%) with fixed the content of phosphorous compound (2 wt%). The PU flame-retardant coatings (TTBAH -10C, -20C, and -30C) were prepared using the synthesized ATBAs and HDI-trimer as curing agent at room temperature. The physical properties of PU flame-retardant coatings with chlorine and phosphorous were inferior to those with phosphorous only and the properties were getting worse with increasing chlorine content. Flame retardancy was tested with three methods. With the vertical method, Complete combustion time of ATBAHs were $259^{\sim}347$ seconds, which means that the prepared coatings are good flame-retardant. With the $45^{\circ}$ Meckel burner method, char lengths of the three prepared coatings were less than 2.9 cm, which indicates that the prepared coatings are 1st grade flame retardancy. With the limiting oxygen index (LOI) method, the LOI values of the three prepared coatings were in the range of $30^{\sim}35%$, which proves good flame retardancy of the prepared coatings. From the results of flame retardancy tests of the specimens that contain the same amounts of flame retarding compounds, it was found that the coatings containing both phosphorous and chlorine show higher flame retardancy than the coatings containing phosphorous alone. This indicates that some synergy effect of flame retardancy exists between phosphorous and chlorine.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.377-384
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• 2014

Recently, the trend toward larger architectural structures continues and accelerates demand for Ultra High Strength Concrete (UHSC) which satisfies structural performance. However, UHSC has weakness in fire and the performance tests are required. In this paper, the change of mechanical properties of 100 MPa grade UHSC exposed to high temperatures ($20^{\circ}C{\sim}800^{\circ}C$) was observed to develop high temperature material model of UHSC: residual compressive strength, modulus of elasticity, property of stress-strain on monotonous loading and property of stress-strain on cyclic loading. In addition, TG/DTA and SEM Images analyses were performed to investigate chemical and physical characteristics of UHSC, and the results of this research were compared with those of previous studies. As a result, UHSC at the heating temperature of $300^{\circ}C$ showed a sharp decrease of residual compressive strength and modulus of elasticity. And It was shown that UHSC had a plastic behavior at more than $400^{\circ}C$ on the cyclic loading and revealed a same tendency in both monotonous and cyclic loading of all heating temperatures. In addition, through TG/DTA and SEM images analyses compared with those from previous studies, it was shown that the deterioration of concrete inner tissue, water evaporation and chemical reaction caused the decrease of residual compressive strength and modulus of elasticity.

• Food Science of Animal Resources
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• v.33 no.6
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• pp.723-729
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• 2013

In this study, the quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen beef were examined. The loin and round of second grade Hanwoo were sliced into 5-7 cm thickness and packed with aerobic packaging. The packaged beef samples, which were frozen by air blast freezing at $-45^{\circ}C$ and electro-magnetic freezing at $-55^{\circ}C$, were thawed by 4 thawing methods with refrigeration ($4{\pm}1^{\circ}C$), room temperature (RT, $25^{\circ}C$), cold water ($15^{\circ}C$), and microwave (2450 MHz). These samples were thawed to the point, which were core temperature reached $0^{\circ}C$. Analyses were carried out to determine drip and cooking loss, water holding capacity (WHC), moisture contents and sensory evaluation. Frozen beef thawed by microwave indicated a lower drip loss (0.66-2.01%) than the other thawing methods (0.80-2.50%). Cooking loss after electro-magnetic freezing indicated 52.0% by microwave thawing for round compared with 41.8% by refrigeration, 50.1% by RT, and 50.8% by cold water. WHC thawing by microwave with electro-magnetic freezing didn't showed any difference depending on the thawing methods, while moisture contents was higher thawing by microwave with electro-magnetic freezing than refrigeration (71.9%), RT (75.0%), and cold water (74.9%) for round. The texture of sensory evaluation for round thawed by microwave result was the highest than refrigeration (4.7 point), RT (6.4 point) and cold water (6.6 point), while sensory evaluation was no significant difference. Therefore, it was shown that microwave thawing is an appropriate way to reduce the deterioration of meat quality due to freezing.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.412-425
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• 2012

Concrete Soil Erosion Control Dam, which blocks flow of debris flow in torrential stream, are reported to lose expected functions due to structural failure and collapses, caused by poor construction, material deterioration and external impacts. In this paper, an integrity assessment technique for debris barriers was proposed, which allows preliminary detection of problems inherent in debris barriers. The proposed integrity assessment technique is a non-destructive method based on SASW method, one of surface-wave tests. In this paper, a practical procedure and analysis guidelines in applying the SASW technique to debris barrier was proposed and its validity was verified using five decrepit debris barriers older than 20-year old. As a result, the SASW method was validated for the reliable grade evaluation method for concrete soil erosion control dam, and the resulting grades turned out to agree with the results determined by Sabang Associations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.193-203
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• 2011

The purpose of this study, looking to which the recycled fine aggregates from waste concrete have a lot of problems as a material for structure purpose, is applying the recycled fine aggregate to Self-Compacting Concrete(In the reminder of this paper, it often referred to as SCC) by using the characteristic which the powder containing the recycled fine aggregates can increase strength and liquidity. In this study, that is, the recycled fine aggregate powder is appropriate for developing high strength(over 40 MPa) and liquidity(JSCE 2 grade), the characteristic of the SCC and it was increased the ratio of mixing the recycled fine aggregates emerging from waste concrete and the normal fine aggregates by 25%, making differential in total 5 levels and applied to SCC. After all, this study was reviewed the physical properties of the fresh concrete, analyzed the mechanical properties and durability of the hardening concrete and tried to ensure the possibility of utilizing the recycled fine aggregates as a material for SCC. As a result, this study reached a conclusion that among the 5-level replacement ratios of the physical, mechanical analysis and the durability characteristics, the normal fine aggregates could be applied up to a replacement ratio of 50% more than the recycled fine aggregates and resulted in a deterioration in performance the replacement ratio larger than 50%. It is judged that the applicability of the real structures should be followed up in order to check the possibility of applying the recycled fine aggregates to real life.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.733-739
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• 2004

Model for optimally dimensioned PE film bag was developed according to fruit size to maintain best quality of 'Fuyu' persimmon in modified atmosphere packaging (MAP) storage based on relationship between quality and oxygen and carbon dioxide in PE film bag. Harvested persimmons were graded into five sizes, and average weights were LL:261, L:217, M:188, S:168, and SS:154 g. Five fruit units of each grade were optimized in five PE film bag sizes of $150{\times}376,\;140{\times}357,\;130{\times}344,\;130{\times}333,\;and\;120{\times}3l8\;mm$. To minimize quality deterioration such as softening and discoloration, optimal oxygen and carbon dioxide concentrations in PE film bag were 0.5-1.0 and 6.0-8.0%, respectively, and optimal thickness of PE film bag according to fruit size were LL:45, L:50, M:55, S:60, and $SS:65\;{\mu}m$. For all fruit sizes, model for PE film bag area $(mm^2)$ was good quadratic simple equation by fruit weight (g): $Y=-4055.707+627.993X_1-0.701{X_1}^2$. Model far optimal oxygen and carbon dioxide (Y) concentration in PE film bag was suited to linear multiple equation by fruit weight $(X_1,\;g)$ and PE film thickness $(X_2,\;{\mu}m)$. Equations for oxygen and carbon dioxide concentrations (%) were $Y=5.798-0.0109X_l-0.0491X_2\;and\;Y=-2.427+0.01927X_l +0.09646X_2$, respectively.

• Korean Journal of Heritage: History & Science
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• v.45 no.1
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• pp.70-85
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• 2012

Uiseong Tamni-ri Five-storied Stone Pagoda is composed of andesitic tuff and partially combined with tuff breccia and fine-grained granite. The andesitic tuff is identical to basement rock of Geumseongsan Mountain based on lithological, mineralogical and geochemical characteristics. The pagoda has suffered physical weathering such as crack and scaling, discoloration and biological colonization with complex reaction. Expecially, dark gray and brown discoloration appeared whole over the surface of the pagoda, and three to five-layered exfoliation and granular disintegration dominantly occurred in the fourth and fifth roof stones. It is assuming that the stone elements of the pagoda are evaluated as third to forth grades (average third grade) of weathering compared to fresh rock in Geumseongsan Mountain. The physical strength of the stone elements shows low values in the south and west sides of the pagoda that corresponds high weathering degree of the west side due to exfoliation, crack and granular disintegration. It is necessary to investigate the pagoda for precise deterioration assessment, monitoring and conservation treatment.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.287-296
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• 2022

Objective : Although radiotherapy (RT) is recommended for multiple myeloma (MM) involving spine, the treatment of choice between reconstructive surgery with RT and RT alone for pathologic vertebral fractures (PVFs) associated with structural instability or neurologic compromises remains controversial. The purpose of this study was to evaluate the clinical efficacies of reconstructive surgery with adjuvant RT for treatment of MM with PVFs by comparing with matched cohorts treated with RT alone. Methods : Twenty-eight patients underwent reconstructive surgery followed by RT between 2008 and 2015 in a single institution, for management of PVFs associated with structural instability of the spine and/or neurologic compromises (group I). Twenty-eight patients were treated with RT alone (group II) after propensity score matching in a 1-to-1 format based on instability of the spine, as well as age and performance. Clinical outcomes including the overall survival rates, duration of independent ambulation, neurological status, and numeric rating scale (NRS) for back pain were compared. Results : Clinical and radiological features before treatment were similar in both groups. The median survival period was similar between the two groups. However, the mean duration of independent ambulation was significantly longer in group I (88.8 months; 95% confidence interval [CI], 66.0-111.5) than in group II (39.4 months; 95% CI, 25.2-53.6) (log rank test; p=0.022). Deterioration of Frankel grade (21.4% vs. 60.7%, p=0.024) and NRS for back pain (2.7±2.2 vs. 5.0±2.7, p=0.000) at the last follow-up were higher in the group II. Treatment-related complications were similar in both groups. Conclusion : In patients with unstable PVFs due to MM, reconstructive surgery may yield superior clinical outcomes compared with RT alone in maintaining independent ambulation and neurological status, as well as pain control despite similar median survival and complications.