• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.47-54
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• 2017

Cement industry is typical carbon-emission industry. If the industrial by-products(granulated blast-furnace slag (GGBFS), fly ash, etc.) are used a large amount, it might be able to reduce cement consumption and mitigate carbon emissions. In this case, however, decrease of early strength is relatively large. Therefore, there is a limitation in increase of the amount of substitute. Considering these circumstances, it would be a good solution to reduce carbon emissions in cement industry to improve the performances of mixed cement through proper alkali-activation in Portland blended cement using GGBFS or fly ash. Therefore, this study prepared concrete in ready-mixed concrete manufacturing facilities with an addition of a binder which used 2.0% modified alkali sulfate activator after mixing Portland cement, GGBFS and fly ash in the ratio of 4:4:2 and assessed its basic properties. The results found the followings: The use of modified alkali-sulfate activator slightly reduced slump and shortened setting time. As a result, bleeding capacity decreased while early strength improved. In addition, there is no big difference in carbonation resistance. It appears that there should be continued experiments and analyses on the related long-term aged specimens.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.133-142
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• 2011

The purpose of this study is to analyze the problems of the parties involved in the issuance of apartment housing development projects. The adapted research method selected four apartment housing development as PF ABCP projects. This study carried out the case about participant institution of PF ABCP funding project including developer, constructor, financial institution so as to draw problems by participant institution. On the basis of the selected case, this thesis proposes methods for involved parties to negotiate and work out problems of the PF ABCP. The results of this study are as follows 1) Launching long-term project financing should be developed, including operating funds and strengthen the ABS and ABCP issuance of credit assessment procedures, combined with the simplicity of the instruments. 2) The Low-risk contract for the construction of simple managerial focus should be the construction, financial institutions essentially dependent on project financing feasibility verification purpose loans to prevent the division a true story, the development should be of interest to be preserved. The proposed included, among other, partial guarantee based on the construction plan financial institutions' share-based investment, and the supplement of legal issues.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.805-814
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• 2012

Intermittent or periodic signals with undulating amplitudes of mobile devices cause interference noise at audible frequency to the sound system which is installed nearby. In this regard, it is recently issued that the intermittently transmissions of LTE mobile phones cause the interference noises with sound systems, similar to that of GSM mobile phones. For retaining the immunity to noises, a national regulation KN20 suggests a 1 kHz AM 80 % and a CDMA modulation signal as reference signals for immunity test of sound and television broadcast receiver. In this paper, the effects of interference noises of AM and CDMA are compared with those of GSM and LTE, and the improvement of reference signal for national immunity test of sound systems is suggested. It is recommended to delete the CDMA modulation signal from reference signals for immunity test because it hardly cause interference noise with sound systems. On the other hand, it is desirable to select the modulation signal of LTE instead of CDMA as a reference signal for immunity test of sound system and television broadcast receiver because many people use the LTE service and it is analysed that the LTE signal causes considerable interference noises.

• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.26-32
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• 2009

The use of natural environments to change lifestyle and health has been long recognized. In particular, forests, trees, and open space have been shown to promote mental health. In this study, we examined the effectiveness of the structured psychotherapeutic program using forest environment ("forest activity program") to improve the symptoms of nine patients with Major Depressive Disorder (MDD) who were taking variable doses of antidepressants. We assessed the depressive symptoms, quality of life, and autonomic nerve regulation among the MDD patients. Hamilton Rating Scales for Depression (HRSD) scores significantly decreased after the forest therapy (13.56 vs. 5.56, p=0.003), and some subscores of Short Form 36 health survey questionnaire (SF-36) and heart rhythm coherence are improved as well. Combined with antidepressant pharmacotherapy, the structured psychotherapeutic program using forest environment showed an improved health status for MDD patients and thus has potential as an adjuvant treatment for MDD, especially for rehabilitation and relapse prevention.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.452-458
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• 2012

Rare earth elements fertilizer and Ca were sprayed on eight-year-old 'Fuji'/M.9 apple trees during two consecutive seasons, and fruit quality was quantified at harvest and 5-month long storing in a commercial cooling house at $4^{\circ}C$ and 80~85% RH. In the first season, single-sprayed of rare earth elements fertilizer showed appreciable accumulations of its elements (La, Pr, Gd, and Nd) in the fruit. In the following season, application of higher doses accumulated higher amount, indicating that the accumulation of rare earth elements was dose-dependent. However, rare earth elements did not affect the accumulations of Ca, Mg, and K in 'Fuji' apple fruit showed that there was no interaction between rare earth elements and these macronutrients. Double-spray of 0.2% rare earth elements increased fruit redness at harvest and had exhibited better color. Although at harvest it did not show significant effects on fruit weight, pulp firmness and titratable acidity (TA), but had pronounced effects on inhibiting fruit softness and retarded decrease of TA during storing. Furthermore, it reduced respiration rate and inhibited ethylene production during storing indicated that rare earth elements may be an alternative for prolonging the shelf life of 'Fuji'/M.9 apple fruit.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.927-935
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• 2019

Screw-failure accidents in small ships frequently occur in coastal waters. In particular, vessels' propulsion systems are frequently coiled due to objects such as fish-nets and ropes that float on the sea. The failure of the ship's propulsion system can cause primary accidents such as ship operation delays and drifting due to loss of power; furthermore, the possibility of secondary accidents such as those involving operators in the underwater removal of rope stuck in a propeller. Ships that do not have the proper tools to solve these problems must be either lifted onto land to be repaired or divers must dive directly under the ship to solve the problem. Accordingly, some small vessels have been equipped with rope-cutter devices on the propeller shaft to prevent ship propeller system accidents in recent years; however, they are not being applied efficiently due to the cost and time of installation. To solve these problems, this study develops an underwater rope-cutter device and controller for the removal of propeller and shaft foreign material in small vessels. This device has simple structures that use the principle of a saw. Meteor gears and crank pins were used for the straight-line rotation of saw blades of the underwater rope-cutters to allow for long strokes. Furthermore, the underwater rope-cutting machines can be operated by being connected to the ship battery. The user, a non-professional, can ensure convenience and stability by applying reverse current prevention and a speed control circuit so that it can be used more conveniently and safely.

• Korean Institute of Interior Design Journal
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• v.24 no.5
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• pp.108-116
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• 2015

This study intends to research the spatial characteristics of Asian interim housing that accommodates sufferers pro tempore after disasters. The scope of this research covers the interim spaces used for housing people after natural disasters that occurred in Asia for the past fifteen years. Within this scope, literature review was conducted as the basis to derive the characteristics and environmental elements of interim housing, which provided the criteria to compare and evaluate cases of interim housing along with characteristic elements required of interim housing found in previous studies. According to literature review, interim housing can be classified by life-span, region, economy, climate, type, number of household, square measure, residential cost, structure/material, and service life. Within the scope of the present research, literature review showed a total of twenty-eight cases of interim housing in fifteen countries revealing a high rate of disaster occurrence in the subtropic and tropic climate of Southeast Asia. A great percentage of interim housing was used for long-term stay of over a year. The structure of interim housing varied from lightweight steel, wooden, masonry, membrane, to traditional structure and the type were divided into temporary shelter, transitional housing, temporary housing, and permanent housing. Followed by literature review, the characteristics required of post-disaster interim housing were analyzed based on previous research and case studies. The characteristics of interim housing can be divided into environmental, technological, and socio-cultural ones. Sub-characterical items according to such division include amenity, health, surroundings, structure, convenience, eco-friendliness, safety, communication, and locality. As a result of evaluation, most items met the required characteristics of interim housing, while technological characteristics such as structure and convenience varied with the types of interim housing and appeared even unnecessary in some cases. According to analysis, amenity is maintained through the structural and material characteristics of interim housing and is also facilitated by increasing number of infrastructure such as educational, sanitary, and convenience facilities provided by the governmental and organizational bodies. It is expected that this study will be utilized as preliminary data for follow-up studies that improve the environment of post-disaster interim housing suitable for domestic circumstances in environmental, technological, and socio-cultural respects.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.153-159
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• 2005

Recently, various novel numerical models based on Navier-Stokes equation rave been developed for calculating wave motions in the sea with coastal or ocean structures. Among those models, Volume Of Fluid (VOF) method might be the most popular one, and it has been used for numerical simulations of wave motions including complicated phenomena of wave breakings. VOF method, however, needs enormous computation time and large computational storage memories in general, thus it is practically difficult to use VOF method for calculations in the case of random waves because long and stable computation ( e.g. for more than 100 significant wave periods) is required to obtain statistically meaningful results. On the other hand of the wave motion is potential motion, Boundary Element Method (BEM), which is a much faster and more accurate method than VOF method, am be effectively used. The aim of this study is to develop a new efficient model applicable to calculations of wave motion and/or wave-structure interactions under random waves. To achieve this, a strictly combined BEM-VOF model has been developed by making the best use of both methods' merits; VOF method is used in a restricted fluid domain around a structure where complicated phenomena of wave breakings may exist, and BEM is used in the other domains far from the disturbance where the wave motion may be assumed to be potential. The verification of the model was performed with numerical results for Stokes'5th order wave propagation and a random wave propagation.

• Journal of Conservation Science
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• v.25 no.1
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• pp.25-38
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• 2009

The Gyeongju Seokbinggo (Treasure No. 66) is an ice-storing stone warehouse, consisting mainly of alkaligranite which shows milky white color and medium-grained textures with drusy cavities. As results of deterioration assessment, the deterioration rates were determined as crack (12.5%), disjoining (6.7%), breaking-out (25.1%), exfoliation (20.9%), efflorescence (6.5%), brown discoloration (9.8%), darkgray discoloration (2.0%) and biological discoloration (36.5%). Comprehensive physical deterioration rate and discoloration rate were calculated as 43.7% and 68.7%, respectively, that indicates the Seokbinggo has been severely weathered. Indoor relative humidity was above 90% except in winter season. Indoor microclimate was hardly fluctuating although indoor microclimate was dependent on the outdoor climate. The main cause of deterioration was high relative humidity and a long time of wetness due to penetration of rain, underground water and condensation. It was identified that the water brought out biological discoloration, dissolution of minerals, structural movement and efflorescence, and the dust from the ground soil in front of the entrance accelerated brown and dark gray discoloration on the stone surface.

• Applied Microscopy
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• v.29 no.2
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• pp.189-193
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• 1999

The response of ameloblast to long term (3 weeks) exposure to fluoride was examined in continuously erupting mandibular incisors of pregnancy rats as compared to control rats receiving a similar diet (Teklad L-356) but no sodium fluoride in there drinking water. Rats were started on water containing 0 ppm, 100 ppm, 200 ppm, and 300 ppm NaF at the beginning of pregnancy. To examine on the ultrastructural changes of the ameloblast, electron microscopy was used. The results indicated that rat incisors expressed two major changes in normal amelogenesis that could be attributed to chronic fluoride treatment. The fluoride produces marked alteration in the fine structure of ameloblast from teeth of young rats, such as large confluent distensions of the endoplasmic reticulum and swelling of isolated mitochondria, in particular on the morphology of the rough-surfaced endoplasmic reticulum. A graded series of alterations to these organelles were produced, and the severity of the changes would seem to be dependent on dose and time. This experimental data suggested that exposure prolonged of animal to high level of fluoride appears to induce morphological changes in the normal appositional growth and initial mineralization of enamel created during amelogenesis.