• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.99-106
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• 2007

To satisfy with the increased requirements of cost reduction, labor saving, and rapid construction, the purpose of this study is to investigate the structural behavior of PSC monolithic and spliced girders. Three tests were conducted on small-scale girder specimens. This paper presents the result of experimental studies in terms of the load-deflection behavior. Different joint type and tendon amount were investigated as major variables. The monolithic girder was arranged with three tendons. The spliced girder consisted of five segments connected by three tendons. In addition, five-segmented girders connected by more than three tendons were built to examine the effect of the tendon amount. The experimental results show the difference of behavior between monolithic and spliced girders. Moreover, nonlinear finite element method analysis was utilized to verify the experimental result.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.59-66
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• 2011

Purpose: We wanted to evaluate the clinical and radiological outcomes and the prognosis of various surgical treatments for the distal clavicle fracture with an acromioclavicular joint injury. Materials and Methods: A retrospective study of 21 patients with a minimum of 12 months follow up was done. We classified acromioclavicular (AC) injury into type I (only intra-articular fracture (IAF), 5 cases), type II (IAF with widening of the AC joint > 7 mm, 9 cases) and type III (IAF with AC joint superior subluxation > 50%, 7 cases). The distal clavicle fractures were fixed using plate (9 cases), mini screws (1 case), K wire and tension band wiring (10 cases) and transarticular pinning (1 case). Acromioclavicular or coracoacromial ligament reconstruction was not done in all the cases. Results: In 20 of 21 cases, bone union was achieved at an average of 8.4 weeks. Traumatic arthritis (5 cases), AC joint widening (4 cases) and AC joint subluxation (2 cases) were noted at the last follow up. The average UCLA score was 32.6 in the type I AC joint injuries, 34 in type II and 34.1 in type III. There was no relationship between the clinical outcomes and the preoperative AC joint injury pattern, postoperative traumatic arthritis, AC joint widening or AC joint subluxation (p>0.05). Conclusion: Satisfactory results were achieved by acute reduction and firm fixation of the distal clavicle fracture with AC joint injury. There was no relationship between the pattern of AC joint injury, the residual radiologic findings and the functional outcome.

• Journal of International Area Studies (JIAS)
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• v.22 no.2
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• pp.217-244
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• 2018

As Chinese insurance market grows rapidly due to market reforms, China got recognition as second-largest insurance market in the world in 2016. However Korean insurance companies have had difficulties to grow in Chinese insurance market despite Chinese participation in the World Trade Organization (WTO) and the growth of chinese insurance market. The reason for the decline in Korean insurance companies is economic retaliation due to the deployment of THAAD in Korea. However, this is not a fundamental reason. The underlying cause of the effects of economic retaliation is the result of insufficient negotiations in Korea-China FTA services sector. In Service sector of Korea-China FTA, the level of concession between Korea and China differs greatly, when comparing China and South Korea's FTA. In addition, it has only been a few years since China collected the position of the WTO Doha Agenda, which currently deals with concessions on intellectual property rights and services. More important is that the Korea-China FTA service sector, as it stopped short of being protected by the most-favored-nation state treatment level when Korean insurance companies entered China. Further negotiations to supplement the weak points in the Korea-China FTA service sector were promised in December 2017, but international tensions over THAAD deployment made it impossible to hold such negotiations. However, due to changes in international affairs in 2018, the first additional negotiation was decided and held. This paper implicates strategies of further negotiation between Korea and China for service and investment chapter. Consequently, the aim of this paper suggests directions how to re-enter Chinese insurance market to Korean insurance companies.

• Journal of Dairy Science and Biotechnology
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• v.34 no.1
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• pp.37-41
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• 2016

Melatonin is a hormone produced by the pineal gland in dark conditions. It plays a major role in the regulation of the sleep-wake cycle. Melatonin synthesis is known to be suppressed by environmental light. Cortisol is a steroid hormone that is a major indicator of physiological alterations due to stressful stimuli. It also displays a circadian rhythm, like melatonin. The highest levels are encountered during early morning and the lowest levels are observed at around midnight. In the present study, the effects of milking time on the melatonin and cortisol concentrations of raw milk and milk powder at the summer and winter solstices were examined. The melatonin concentration in milk increased significantly if cows were milked in the dark at night (p<0.05). The melatonin concentration in milk powder showed the same pattern with respect to the milking time (p<0.05). However, no significant difference in the cortisol concentration was observed between day- and night-time milk. Although the time of day did not affect the level of milk cortisol, seasonal factors affected the release of cortisol in milk (p<0.05). In conclusion, night-time milk is rich in endogenous melatonin. In this respect, it has potential applications for the development of melatonin rich-dairy products, which serve as natural sources of melatonin.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.727-735
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• 2012

Recently, a high-strength strand of 2400 MPa was developed using domestic technologies. In 2011, KS D 7002 was revised to cover the newly developed high-strength strands to support their practical usage. Presently, however, discussions and evaluations are not sufficient on the mechanical properties of the strands and their performance in structural members. Also, there were no detailed reviews on the need to revise the current design code for practical use of the high-strength strands. In this study, flexural behavior of a member with the high-strength strands was estimated through sectional analysis and a review and comparison of the domestic and foreign design codes were conducted considering the analysis results. Also, the need for the revision of the design code was discussed. Such discussion especially focused on the estimation of the stress in strand, which related with various issues such as determination methods for yield point of strands, time-dependent loss of prestressing force, estimation of stress in strand at member failure, and net strain limit for ductile failure of member. The discussion revealed that some parts in the design code need a revision and the further studies are required.

• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.33-40
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• 2016

The KCI-12 and ACI 318-14 design codes limit the maximum yield strength of shear reinforcement to prevent concrete compressive crushing before the yielding of shear reinforcement. The maximum yield strength of shear reinforcement is limited to 420 MPa in the ACI 318-14 design code, while limited to 500 MPa in the KCI-12 design code. A total of eight post-tensioning prestressed concrete beams with high strength shear reinforcement were tested to observe the shear behavior of PSC beams and the applicability of the high strength reinforcement was thus assessed. In the all PSC beam specimens that used stirrups greater than maximum yield strength of shear reinforcement required by the ACI 318-14 design code, the shear reinforcement reached their yield strains. The observed shear strength of tested eight PSC beams was greater than the calculated ones by the KCI-12 design codes. In addition, the diagonal crack width of all specimens at the service load was smaller than the crack width required by the ACI 224 committee. The experimental and analytical results indicate that the limitation on the yield strength of shear reinforcement in the ACI 318-14 design code is somewhat under-estimated and needs to be increased for high strength concrete. Also the application of high strength materials to PSC is available with respect to strength and serviceability.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.809-820
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• 2008

A new modified full scale double tee slabs with the length of nib plate - 1,500 mm were suggested, designed, and experimentally evaluated up to the loading of flexural failure. This slabs were composed of the tee section which was same to original PCI double tee and the plate section which was modified in a new shape, and the prestressing force was applied at the bottom of tee section only. This specimens were made from the domestic precast factory. The safety and serviceability of the modified nib plate with the dapped ends were evaluated up to the ultimate flexural strength of tee section. As the experimental loading increased, the flexural crackings developed first in the bottom of the slab and they changed to the increased flexural shear and inclined shear crackings in the nib and dapped portion of the double tees. The suggested modified double tee slabs failed in ductile above the design loading with many evenly distributed flexural crackings. The thickness of nib plate - 250 mm does not show any cracking under the service loading and show several minor flexural cracking up to the ultimate state of tee portion. The proposed specimens were satisfied with the strength and ductility requirements in the design code provisions in the tests. Additional experimental tests are required to reduce the depth and tensile reinforcement of nib plate concrete for the practical use of this system effectively.

• Journal of Oral Medicine and Pain
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• v.34 no.3
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• pp.325-331
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• 2009

The objective of this study was to describe the prevalence of the headache attributed to Temporomandibular disorder(TMD) symptoms and to investigate the relationships of headache and TMD. 66 patients seeking care for signs and symptoms of Temporomandibular disorders(TMD) and Orofacial pain in the department of oral medicine, Dental Hospital, Chosun University, from January, 2008 to June, 2008, were recruited. The obtained results were as follows : 1. A muscle and TMJ origin combined was the most common in study populations(54.55%), grouped as TMD classification. 2. Tension type headache was the most common in study population(89.39%), grouped as headache classification. 3. 36 patients out of 66(54.55%) had headaches which related to TMD. 4. Out of 36 patients who had suffered the headache which were attributed to TMD, 19 patients(52.78%) described that their headache related to TMD was different from their own primary headaches. In conclusion, headache attributed to TMD is relatively common in the patients who had headaches and TMD symptoms together. And the new headache patterns may related to headache and TMD chronification. Larger-scale studies and more specified and controlled comparison study is needed to confirm the relationship between the headache and TMD.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.91-99
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• 2010

In order to strengthen RC structures, various strengthening methods have been used. Particularly, external tendon strengthening method is very popular method to strengthen damaged structures in terms of efficiency, ease, economics. In this study, improved anchorage elements using the lifting hole were proposed to strengthen PSC or RC girder without any damage. Two types of anchorage elements were proposed and these elements were applied on six RC beams. Also, three types of existing anchorage elements were applied on three RC beams. Otherwise, any anchorage element was not applied on one RC beam to used as a control beam. To analyse behavior of these elements, static load tests were carried out. Test variables were anchorage shapes, prestressing level on the steel bar and tendon profiles. Deflections, strains and modes of failure were recorded to examine the strengthening effects of the beams. Ductility index and tendon stress were analyzed by comparing cracking load, yielding load and ultimate load. As a result, proposed anchorage elements using lifting hole were superior to existing anchorage elements in terms of strengthening effect and furthermore, they showed ductile behavior based on energy method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.130-137
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• 2019

Precast concrete (PC) structure is one of the type of the structures which is made in a facility prior to installing it to a construction field. The contact surfaces between two PC structures should be treated for obtaining enough binding force by inducing prestressing force. However, in the many cases, the contact surface causes the crack and leakage of water. These cracks and water leakage can cause the corrosion of the rebar, and the corrosion of the rebar can severely reduce the long-term durability. In this study, the SMA wire connector is suggested to solve the problem with the contact surfaces between two PC structures. The pull-out resistance of the suggested SMA wire connector is evaluated by conducting the tests to find the effect of the number of wires, shape of connector part, and shape memory effect. As a result of this study, the empirical formula is suggested to estimate the pull-out resistance related with the effects of the shape of the connector, shape memory effect, and the adhesive force. The validity between the estimated pull-out resistance and the measured value is confirmed.