• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.25-31
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• 2023

The dispute over the Northern Limit Line in the West Sea has been sharply opposed since the U.N. commander set it in August 1953 with the aim of preventing accidental armed conflict between the two Koreas in the waters of the Korean Peninsula. In 2022, for the first time since the division, North Korea made a missile provocation beyond the NLL. The purpose of this study is to identify how the research on the NLL, which is under way by North Korea's actual provocation, has been conducted and to suggest a direction to proceed. This study examined the trend of research using a total of five academic information DBs, including RISS and Scholar, focusing on academic papers studied on NLL from 1998 to 2023. As a result of examining the current status of each year, field, and research method, significant differences in research volume were identified according to the government's relationship with North Korea, and the research field had the most introduction of the concept of NLL and historical background, confirming the need to expand to more diverse fields to have international legal justification and justification for the NLL, considering the changing international environment according to the logic of power. In terms of final research methods, most of them were literature studies, so the need for quantitative research using interviews, surveys, and big data was also found. It is hoped that the analysis results of this paper will play a positive role in setting the research direction for the international response of the NLL in the future amid the interests of the international political environment that is still ongoing.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.321-329
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• 2013

Recently, the medium-low level radioactive waste from nuclear power plant must be transported from temporary storage to the final repository. Medium-low level radioactive waste, which is composed mainly of the liquid ion exchange resin, has been consolidated with cementitious material in the plastic or iron container. Since cementitious material is brittle, it would generate cracks by impact load during transportation, signifying leakage of radioactive ray. In order to design the safety transporting equipment, there is a need to check the compressive strength of the current waste. However, because it is impossible to measure strength by direct method due to leakage of radioactive ray, we will estimate the strength indirectly by the dynamic modulus of elasticity. Therefore, it must be identified the relationship between of strength and dynamic modulus of elasticity. According to the waste acceptance criteria, the compressive strength of cement based solid is defined as more than 3.44 MPa (500 psi). Compressive strength of the present solid is likely to be significantly higher than this baseline because of continuous hydration of cement during long period. On this background, we have tried to produce the specimens of the 28 day's compressive strength of 3 to 30 MPa having the same material composition as the solid product for the medium-low level radioactive waste, and analyze the relationship between the strength and the dynamic modulus of elasticity. By controling the addition rates of AE agent, we made the mixture containing the ion exchange resin and showing the target compressive strength (3~30 MPa). The dynamic modulus of elasticity of this mixtures is 4.1~10.2 GPa, about 20 GPa lower in the equivalent compressive strength level than that of ordinary concrete, and increasing the discrepancy according to increase strength. The compressive strength and the dynamic modulus of elasticity show the liner relationship.

• Journal of the Korean Arthroscopy Society
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• v.6 no.1
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• pp.1-6
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• 2002

Purpose : Evaluation and analysis of the incidence and causes of intraoperative and postoperative complications after arthoscopic anterior cruciate ligament(ACL) reconstruction using bone-patella. tendon-bone (BPTB) auto graft. Materials and Methods : We reviewed 85 cases of arthroscopic ACL reconstruction using BPTB autograft which had been followed up for more than 1 year. Intraoperative complications had been recorded and corrected during the operation. Postoperative complications were analyzed and compared between 3 groups which were classified by the last follow-up period after the operation. Results : There were a few intraoperative complications including patellar fracture(1 case), contamination of harvested graft(1 case), impingement of graft(2 cases), blow-out of tile posterior wall of the femoral tunnel(1 case) and intraarticular retraction of the screw(1 case). The result of the comparison of postoperative complications among the groups shows that the incidence of anterior knee pain, donor site pain and patellofemoral crepitation were significantly decreased after 2 years. But there was no significant decrease in these complications after 3 years. Conclusion : Intraoperative complications after arthroscopic ACL reconstruction using BPTB autograft were due to incorrect technique and carelessness of the operation team, and can be prevented by improvement of surgical technique and accumulation of experience. Postoperative complication were somewhat unavoidable but gradually improved with time; hence, we should consider it for the selection of graft donor.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.35-46
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• 2016

Purpose : BoS(Base of Skull) Frame, the fixation tool which is used for the proton of brain cancer increases the lateral penumbra by increasing the airgap (the distance between patient and beam jet), due to the collision of the beam of the posterior oblique direction. Thus, we manufactured the fixation tool per se for improving the limits of BoS frame, and we'd like to evaluate the utility of the manufactured fixation tool throughout this study. Materials and Methods : We've selected the 3 patients of brain cancer who have received the proton therapy from our hospital, and also selected the 6 beam angles; for this, we've selected the beam angle of the posterior oblique direction. We' ve measured the planned BoS frame and the distance of Snout for each beam which are planned for the treatment of the patient using the BoS frame. After this, we've proceeded with the set-up that is above the location which was recommended by the manufacturer of the BoS frame, at the same beam angle of the same patient, by using our in-house Bos frame fixation tool. The set-up was above 21 cm toward the superior direction, compared to the situation when the BoS frame was only used with the basic couch. After that, we've stacked the snout to the BoS frame as much as possible, and measured the distance of snout. We've also measured the airgap, based on the gap of that snout distance; and we've proceeded the normalization based on each dose (100% of each dose), after that, we've conducted the comparative analysis of lateral penumbra. Moreover, we've established the treatment plan according to the changed airgap which has been transformed to the Raystation 5.0 proton therapy planning system, and we've conducted the comparative analysis of DVH(Dose Volume Histogram). Results : When comparing the result before using the in-house Bos frame fixation tool which was manufactured for each beam angle with the result after using the fixation tool, we could figure out that airgap than when not used in accordance with the use of the in-house Bos frame fixation tool was reduced by 5.4 cm ~ 15.4 cm, respectively angle. The reduced snout distance means the airgap. Lateral Penumbra could reduce left, right, 0.1 cm ~ 0.4 cm by an angle in accordance with decreasing the airgap while using each beam angle in-house Bos frame fixation tool. Due to the reduced lateral penumbra, Lt.eyeball, Lt.lens, Lt. hippocampus, Lt. cochlea, Rt. eyeball, Rt. lens, Rt. cochlea, Rt. hippocampus, stem that can be seen that the dose is decreased by 0 CGE ~ 4.4 CGE. Conclusion : It was possible to reduced the airgap by using our in-house Bos frame fixation tool for the proton therapy; as a result, it was possible to figure out that the lateral penumbra reduced. Moreover, it was also possible to check through the comparative analysis of the treatment plan that when we reduce the lateral penumbra, the reduction of the unnecessary irradiation for the normal tissues. Therefore, Using the posterior oblique the Brain cancer proton therapy should be preceded by decreasing the airgap, by using our in-house Bos frame fixation tool; also, the continuous efforts for reducing the airgap as much as possible for the proton therapy of other area will be necessary as well.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.419-430
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• 2005

We have carried out a statistical analysis on solar wind dynamic pressure pulses during geomagnetic storms. The Dst index was used to identify 111 geomagnetic storms that occurred in the time interval from 1997 through 2001. We have selected only the events having the minimum Dst value less than -50 nT. In order to identify the pressure impact precisely, we have used the horizontal component data of the magnetic field H (northward) at low latitudes as well as the solar wind pressure data themselves. Our analysis leads to the following results: (1) The enhancement of H due to a pressure pulse tends to be proportional to the magnitude of minimum Dst value; (2) The occurrence frequency of pressure pulses also increases with storm intensity. (3) For about $30\%$ of our storms, the occurrence frequency of pressure pulses is greater than $0.4\#/hr$, implying that to. those storms the pressure pulses occur more frequently than do periodic substorms with an average substorm duration of 2.5 hrs. In order to understand the origin of these pressure pulses, we have first examined responsible storm drivers. It turns out that $65\%$ of the studied storms we driven by coronal mass ejections (CMEs) while others are associated with corotating interaction regions $(6.3\%)$ or Type II bursts $(7.2\%)$. Out of the storms that are driven by CMEs, over $70\%$ show that the main phase interval overlaps with the sheath, namely, the region between CME body and the shock, and with the leading region of a CME. This suggests that the origin of the frequent pressure pulses is often due to density fluctuations in the sheath region and the leading edge of the CME body.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.141-142
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• 2001

남서부 경기육괴의 편마암류로부터 분리된 저어콘(zircon) 입자를 대상으로, 이온현미분석기(ion microprobe)를 사용한 U-Pb 연대를 구하였다. 그 결과는 후기 원생대(약 820 Ma) 뿐만 아니라 오르도비스기에 상당한 화성활동이 한반도에 있었음을 지시한다. 우리 나라 후기 원생대의 화성-변성 활동에 대해 알려져 있는 바는 극히 제한적이어서 후속연구가 필수적이며, 이러한 연구는 한반도의 지체구조적 변천사를 로디니아 초대륙(Rodinia supercontinent)의 생성-분리와 관련해 재조명할 수 있는 기회를 제공할 것이다. 또한 오르도비스기의 화성작용은 그동안 논란이 되어 왔던 소위 “칼레도니아(Caledonian)” 변동 (cf. 조문섭, 2000)에 대한 또 다른 증거를 제공해준다. 저어콘의 연대측정은 서호주의 커튼공업대학교에 설치되어 있는 SHRIMP-II(Sensitive High-Resolution Ion Microprobe-II; 고감도-고분해능 이온현미분석기)를 사용하였으며, 시료 준비 및 분석방법은 기존에 보고된 바와 같다 (e.g., Kinny et al., 1999). 분석된 3개의 암석 시료(1006-5, 8, 9)는 경기육괴의 남서부에 위치한 홍성 지역의 정편마암들이다. 1006-8 시료는 Turek and Kim (1996)이 전통적인 방법을 사용해 687$\pm$5 Ma의 U-Pb 저어콘 연대를 보고한 바 있는 화강암질 편마암 (시료번호, KJ43)에 해당된다. 두 개의 다른 시료는 1006-8 주변에서 산출하는 전형적인 경기육괴의 편마암류로서 화강암질 정편마암이다. 이들 시료로부터 분리된 저어콘 입자들은 대부분 화성기원의 누대구조와 자형의 결정형태를 보여준다. 과성장띠(overgrouth rims)는 1006-5 시료에서 흔하게, 그리고 1006-9 시료에서 매우 드물게 관찰된다. 음극선발광(cathodoluminescence) 영상의 해석을 통해 저어콘 결정의 성장사를 유추하였으며, 이를 바탕으로 이온현미분석 점(spot)을 정하였다. U-Pb-Th 자료는 퍼스(Perth) 저어콘 스탠다드 (CZ3, 564 Ma, $^{206}$Pb/$^{238}$U=0.0914)를 사용하였다. 아래에 기술하는 연대는 모두 $^{206}$Pb/$^{238}$U 연대에 해당된다. 두 개의 화강암질 편마암 시료로부터 구한 U-Pb 저어콘 연대는 각각 812 $\pm$ 14 Ma(1006-8)와 822 $\pm$ 17 Ma(1006-9)로 분석오차 내에서 서로 일치한다. 이 결과는 춘천 및 전곡 지역의 석류석 각섬암에서 보고된 Sm-Nd 전암연대(852 $\pm$ 24 Ma 및 824 $\pm$ 143 Ma; Lee and Cho, 1995; Ree et al., 1996)와 잘 부합한다. 따라서 후기 원생대 기간 중 화성활동이 한반도에서 광범위하게 일어났음을 시사한다. 한편, 1006-9 시료에서는 예외적으로 한 개의 저어콘 입자 주변부(rim)에서 매우 얇은 과성장띠가 관찰되었으며, 두 개의 점 분석으로부터 구한 U-Pb 저어콘 연대는 약 235 Ma이다. 이 띠는 또한 변성기원의 저어콘에서 흔히 관찰되는 작은 W (<0.05) 비를 보인다. 1006-5 시료는 위 두 시료로부터 수 km 떨어진 지점에서 채집하였으나, 저어콘 연대는 상이한 기록을 보여준다. 즉 매우 작은 Th/U (<0.01) 값을 갖는 저어콘의 주변부에서 223 $\pm$ 5 Ma의 연대가 잘 정의되며, 이는 1006-9 시료에서 관찰된 결과와 함께 트라이아스기의 고온변성작용이 백립암상에 가까운, 매우 높은 온도에 달하였음을 지시한다. 한편 저어콘의 중심부는 335-473 Ma의 비교적 넓은 연대 분포를 보인다. 이는 저어콘이 실제 성장한 연대를 지시하기보다는 트라이아스기의 변성작용에 따른 납손실(Pb loss) 그리고 누대 규모보다 더 큰 빔 크기(beam size, 약 30 $\mu\textrm{m}$)의 영향일 것으로 해석된다. 또한 저어콘이 다양한 외래물질로부터 기원했다는 증거가 관찰되지 않으므로, 이 정편마암의 모암은 오르도비스기(약 430-470 Ma)에 관입하였을 것으로 생각된다. 따라서 그동안 논란이 되어 왔던 소위 “칼레도니아” 변동이 한반도 내에 실존하였을 가능성을 시사한다. 이상의 결과를 종합하여 볼 때, 경기육괴의 변성암류는 후기 원생대 이후 다양한 저어콘의 성장사를 기록하고 있음을 알 수 있다: 즉 (1) 후기원생대(약 820 Ma)의 화성작용; (2) 오르도비스기(약 450 Ma)의 화성작용: 그리고 (3) 트라이아스기 (약 223 Ma)의 부분용융을 수반한 고온 변성작용으로 대표된다. 이러한 지질연대는, 옥천변성대에서 얻어진 756 Ma의 저어콘 연대(Lee et al., 1998)와 더불어, 친링-다비-수루(Qinling-Dabie-Sulu) 대륙 충돌대와 양쯔 지괴에서 보고된 지질연대 결과와 잘 부합한다. 따라서 지구연대학적으로 경기육괴가 북중국보다는 대륙충돌대를 포함하는 남중국지괴에 속할 것으로 결론지을 수 있다.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.94-99
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• 2011

Purpose: As the number of people enjoying skiing and snowboarding which are two popular winter sports has been increasing, wearing helmet during doing these sports has been needed for safety. The rates of head or face injury have decreased after using helmet. However the effect that wearing helmet has on cervical damage is not yet to be known. So through this research we intend to be helpful in developing effective program and safety equipment. Materials and Methods: During two seasons from December 2009 to march 2011, cased 658 cervical injuries within 14538 admittance in medical center of major resort due to skiing and snow-boarding injuries. For survey and research model, one year before the research year conducted a pilot study. Admittance were 432 male and 226 female, advanced 273 and 385 novice. We divided them into two groups depending on wearing helmet, measured cervical damage ratio and injury mechanism, and researched the severity of damage and diagnosed injury. Each group used SPSS 12.0 (SPSS Inc., Chicago, IL, USA) to process data statistically. Results: The number of patients was 312 in skier and 346 in snow boarder. Patients wearing helmet were 146 in skier and 127 in snow boarder. Classification of each injuries were confirmed as 292 cases of simple sprain, 359 bruising, 6 cervical fractures and 1 case of dislocation. Classification of injury mechanisms were 287 of human collision, 212 material collision, 108 of slip down by oneself, 39 of falling and 12 cases of etc. In cases wearing helmet ski 78/ snow board 70 were simple sprain, ski 64/ snowboard 68 were shown as bruising, ski 1/ snow board 2 had cervical fracture or dislocation. The ratio of cervical sprain increased in cases of wearing helmet compared to non-wearing cases and there was a statistical significance (p<0.001). The ratio of cervical contusion increased significantly in non-wearing helmet user (p<0.05). However, there was no significant increase in fracture and dislocation compared between helmet user and non-user (p> 0.05). Conclusion: In this study, wearing helmet had no relation to additional cervical injury occurrence or severity among skiers and snow boarders. The ratio of cervical sprain increased significantly in helmet user with person to person accident. However, the cervical contusion decreased. On this ground, further biomechanical studies are required and modified helmet will be necessary.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.40-49
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• 1999

A laboratory flume experiment, using turbulence-generating acryl tank and natural sediments, was conducted to investigate the effects of salinity, concentration of suspended sediment, turbulence and clay minerals on the flocculation and settling of fine-grained suspended sediments. While experiments were run, a sequence of water samples were taken near the bottom of the tank to analyze the variations of size distribution and relative contents of clay minerals. The results of the salinity experiment indicate that median settling velocity ($W_{50}$) increases linearly with salinity. Different settling processes of suspended sediments under variable concentrations appear to be predictable, depending upon the range of the suspension concentration. At concentrations less than 200 mg/l, $W_{50}$ is rarely varied with concentration probably because of the individual--grain settling mode. In the range of 200 to 13,000 mg/l show $W_{50}$ and concentration a good relationship following an empirical formula: $W_{50}=0.45C^{0.44}$. This relationship, however, no longer holds in concentrations exceeding 13,000 mg/l; instead, a more or less reverse one is shown. This result suggests an effect of hindered settling. The turbulence effect is somewhat different from that of concentration. Turbulence accelerates the flocculation and settling susepended sediments at low concentration (200 mg/l), whereas at high concentration turbulence breaks floes down and impedes the settling. Size distribution of suspended sediments sampled near the bottom of the tank tend to be more negatively skewed and leptokurtic in turbulent conditions compared to those in static conditions. The clay mineral analysis from the sequential water samples shows that over time the content of smectite decreases most rapidly with illite remaining concentrated in suspension. This means that smectite, among other clay minerals, plays the most effective role in the flocculation of fine-grained sediment in saline water.

• Journal of the Korea Society of Computer and Information
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• v.16 no.5
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• pp.79-91
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• 2011

In this paper, a DS (Data Synchronization) server for mobile communication environments is constructed and the suitability and the performance of its operations are validated. The DS server provides a way to update the newest data and keep data consistency for clients (mobile devices). In addition, the DS server constructed in this paper supports various synchronization types, and detects all changes and conflicts. In case of data conflicts, the DS server resolves the conflicts according to the several policies implemented in this work. The DS server conforms to the OMA(Open Mobile Alliance) DS standard protocol for interoperability with other mobile devices and servers. In addition to the transmission-by record scheme proposed by the OMA DS standard protocol, the DS server constructed in this paper also provides the transmission-by field scheme for the enhancement transmission performance between the server and clients. In order to validate its operations, data synchronization between the DS server and the SCTS (SyncML Conformance Test Suit), the suitability validation tool provided by the OMA, is performed. The validation results show that the DS server constructed in this paper satisfies all of the test cases except the Large Object function. The Large Object function will be implemented later because the function is not needed for the personal information synchronization process which this paper aims for. Also, synchronization times of the DS server are measured while increasing the number of data and clients. The results of the performance evaluations demonstrate that the DS server is scalable, in the sense that it has not suffered from any serious bottlenecks with respect to the number of data and clients. We expect that this work will provide a framework for various studies in the future for improving mobile DS operations.

• The Journal of the Petrological Society of Korea
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• v.24 no.2
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• pp.107-124
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• 2015

The 'Imjin System' (or Rimjin System) was established in 1962 as a new stratigraphic unit separated from the Upper Paleozoic Pyeongan System based on the discovery of brachiopods and echinoderms of possible Devonian age. Subsequent discoveries of the Middle Devonian charophytes confirmed the Devonian age of the system. The Imjin System is distributed in the Imjingang Belt between the Pyongnam Basin and the Gyeonggi Massif, spans from the eastern areas including Cholwon-gun of the Gangwon Province, Gumchon-gun, Phanmun-gun, and Tosan-gun of the Hwanghaebuk Province, to the western areas of Gangryong-gun and Ongjin-gun of the Hwanghaenam Province, and includes the Yeoncheon Group (metamorphic complex) to the south. Unlike the lower Paleozoic strata in the Pyongnam Basin which solely produce marine invertebrate fossils, the Imjin System yields diverse non-marine plant and algal fossils. Brachiopods of the system are similar to those from the Devonian of the South China Block and include taxa endemic to the platform, implying a close paleogeographic affinity to the South China Block. The Imjin System is generally considered as of Middle to Late Devonian in age, although there have been suggestions that the system is of the Middle Devonian to Carboniferous in age. North Korean workers postulated that the Imjin System was deposited in the current geographic position, where the "Imjin Sea" (an extension of the South China Platform) was located during the Devonian. The Imjin System displays strong local variations in stratigraphy and its thickness. It has recently been reported that the strata are repeated and overturned by thrust faults in many exposures. The Yeoncheon Group a southward extension of the Imjin System, also experienced intense tight folding and contractional deformation. Northward decrease in metamorphic grade within the system suggests that the northern part of the Gyeonggi Massif and the Imjingang Belt are probably an extension of the Dabie-Sulu Belt between the South China and Sino-Korean blocks, and the Imjin System is an remnant of accretion resulted from the collision between the two blocks. In order to understand tectonic evolution and Paleozoic paleogeography of eastern Asia, further studies on stratigraphic, sedimentologic and tectonic evolution of the Imjin System involving scientists from the two Koreas are urgently needed.