• Analytical Science and Technology
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• v.9 no.3
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• pp.253-261
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• 1996

Analytical method for the determination of trace germanium in inorganic matrices by differential pulse polarography(DPP) was studied. The reduction peak of germanium(IV) in perchloric acid solution containing 1, 2, 3-trihydroxy benzene appeared at -0.45V(vs. Ag/AgCl) and the peak current for germanium complex varied linearly with concentration variation. Factors affecting sensitivity and precision for germanium quantification were studied and detection limit under the investigated parameters was 1ng/ml. Inorganic samples were decomposed by fusion with potassium pyrosulfate. Serious interferences of Se(IV), Pb(II), As(III) for the determination of germanium were discussed. Interferences of these elements could be avoided by extraction of germanium from decomposed matrices by $CCl_4$ in 10M HCl solution. The germanium contents of inorganic samples(Pb bf. dust, Cu bf. dust, gneiss, Cu anode slime) were determined by the above method.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.3
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• pp.211-218
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• 2009

Feasibility study of using $Ti0_2$ mist generated by ultrasonic atomization for photocatalytic degradation of gaseous toluene was attempted in this study. For this, the photocatalytic reactor consisting of mist generator and photo-reactor was designed. Most of experimental results showed that steady state reached about 30 minutes after the start of experiments. The effects of $Ti0_2$ concentration, toluene concentration, and UV wavelength on toluene removal ratio were investigated. It was found that the highest removal efficiency was obtained when $Ti0_2$ concentration was 0.6 g/L in slurry. At this condition, it was found that the toluene removal efficiency increased as toluene concentration in feed decreased. In order to investigate the effect of UV wavelength, experiments were carried out using three UV lamps with different UV wavelength. The results showed that the highest removal efficiency was achieved when the lamp with the shortest wavelength were employed.

• Journal of Distribution Research
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• v.1 no.2
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• pp.29-52
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• 1996

The objective of this study is to test Parasurman, Zeithaml & Berry(1985)'s service quality gap analysis model, and to confirm reliability and to confirm reliability and validity of the model. The reliability of the model is adopted, but the validity must be retested in the further study. In the results of the gap analysis model, the correlation between consumer expectations and management perceptions of consumer expectations(gap1) was not accepted. The correlation between management perceptions of consumer expectations and service quality specifications(gap2), the correlation between service quality specifications and the service actually delivered(gap3), and the correlation between services delivered and services promised to consumers(gap4) were accepted. To improve domestic telecommunication service quality, practical guides such as standardization of job roles, cooperation among customer-contact persons, communication between managers and employees, evaluation programs for employee's improvement of service quality, appropriate supports for customer-contact persons were suggested. For generalizing the gap model, additional studies under the different contexts and industries will be needed.

• Journal of the Korean earth science society
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• v.34 no.3
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• pp.195-208
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• 2013

We employed electrical resistivity and optical borehole imaging methods to identify underground cavities and determine ground subsidence rate at the study area affected by land subsidence due to abandoned underground mines. At the study site 1, the anomalous zones of low resistivity ranging between 100 ohm-meter and 150 ohm-meter were observed and confirmed as an abandoned underground mine by subsequent borehole drilling and optical borehole imaging. Although the electrical resistivity survey was unavailable due to the paved surface of the study site 2, we were able to locate another abandoned underground mine with the collapsed mine shaft based on the distribution of the ore veins and confirmed it with borehole drilling. In addition, we measured vertical displacements of underground features indicating underground subsidence by conducting optical borehole imaging 6 times over a period of 43 days at the study site 2. The displacement magnitude at the deep segment caused by subsidence appeared to be 3 times larger than those at the shallow segment. Similarly, the displacement duration at the deep segment was 4 times longer than those at the shallow segment. Therefore, the combination of electrical resistivity and optical borehole imaging methods can be effectively applicable to detect and monitor ground subsidence caused by underground cavities.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.35-35
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• 2020

본 연구는 한남정맥의 최 북서쪽에 위치한 경기도 김포시의 문수산(376m) 일원을 중심으로 식물상을 조사하였다. 본 연구에서 확인된 관속식물은 97과, 241속, 340종, 41변종, 6아종, 2품종 등 총 389분류군으로 조사되었다. 특산식물은 병꽃나무, 복사앵도 및 산이스라지 등 6분류군이 확인되었고, 식물구계학적 특정식물은 I등급은 부싯깃고사리, 비목나무, 삿갓사초, 소사나무 등 15분류군, II등급은 꼬리조팝나무, 돌단풍, 피나무, 오리나무 등 6분류군, III등급은 좀작살나무, 좀개미취, 산벚나무, 병아리꽃나무 등 5분류군, IV등급은 복상앵도, 산복사 등 3분류으로 확인되었다. 환경부에서 지정한 외래종 및 생태계교란 야생식물은 가시박, 단풍잎돼지풀, 도깨비가지, 미국쑥부쟁이, 애기수영, 털물참새피 등 53분류분이 확인되었다. 하지만 선행연구에서 조사되었던 멸종위기종 II급인 매화마름과 산림청지정 희귀식물 위기종 깽깽이풀 2분류군이 조사되지 않아 추후 추가 조사 및 유전자원 현지내외 보전대책을 수립해야 할 것이다.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.288-294
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• 1999

In the flip chip interconnection using solder bump, the Under Bump Metallurgy (UBM) is required to perform multiple functions in its conversion of an aluminum bond pad to a solderable surface. In this study, various UBM systems such as $Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 5\mu\textrm{m}, Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}, al 1\mu\textrm{m}/Ni 0.2\mu\textrm{m} / Cu 1\mu\textrm{m} and Al 1\mu\textrm{m}/Pd 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}$ for flip chip interconnection using the low melting point eutectic 63Sn-37Pb solder were investigated and compared to their metallurgical properties. $100\mu\textrm{m}$ size bumps were prepared for using an electroplating process. The effects of the number of reflows and aging time on the growth of intermetallic compounds(IMC) were investigated. $Cu_6Sn_5$ and $Cu_3Sn$ IMC were abserved after aging treatment in the UBM system with thick coper $(Al 1\mu\textrm{m}/Ti 0.2\mu\textrm{m}/Cu 5\mu\textrm{m})$. However only the $Cu_6Sn_5$ was detected in the UBM system with $1\mu\textrm{m}$ thick copper even after 2 reflow and 7 day aging at $150^{\circ}C$. Complete Cu consumption by Cu-Sn IMC growth gives rise to a direct contact between solder inner layer such as Ti, Ni and Pd, and hence to possibly cause reactions between two of them. In this study, however, only for the Pd case, IMC of PdSn. was observed by Cu consumption. UBM interfacial reactions with s이der affected the adhesion strength ot s이der balls after s이der reflow and annealing treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.552-556
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• 2002

The microstructure and electrical characteristics of A~C's ZnO varistors fabricated according to variable sintering condition, which sintering temperature is $1130^{\circ}C$ and speeds of pusher are A: 2mm/min, B: 4mm/min, C: 6mm/min, respectively, were investigated. In the microstructure, A~C's ZnO varist-ors fabricated variable sintering condition was consisted of ZnO grain(ZnO), spinel phase$(Zn_{2.33}Sb_{0.67}O_4)$ Bi-rich $phase(Bi_{2}O_{3})$, wholly. Varistor voltage of A~C's ZnO varistors sintered at $1130^{\circ}C$ increased in order A < B < C's ZnO varistors. C's ZnO varistor exhibited good characteristics that nonlinear exponent is 31.70. Leakage current of A~C's ZnO varistors exhibited below 2mA at rated voltage. Lightning impulse residual voltage of A's ZnO varistor suited standard characteristics, which is 3.85kV at 2.5kA, 4.4kV at 5kA and 5.16kV at 10kA. After multi lightning impulse residual voltage test of A's ZnO varistor exhibited good discharge characteristics which ZnO varistor reveals no evidence of puncture, flashover, cracking in visual examination. After high current impulse test of A's ZnO varistor exhibited good discharge characteristics, which variation rate of residual voltage is 0.4% before and after test, and revealed no evidence.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.314-329
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• 2015

The fish fauna was investigated from 2010 and 2013 at main stream and tributaries in the Seomjin River which has no estuary dike. The collected fishes were identified into 37,751 individuals of 107 species of 81 genera belonging to 41 families. Among the collected fishes the primary freshwater fishes were 57 species (Relative Abundance: 53.3%), the secondary fishes were 10 species (RA: 9.3%) and the marine fishes were 40 species (RA: 37.4%). The dominant species was Zacco platypus (RA: 28.7%), and the subdominant species was Zacco koreanus (RA: 15.0%). The endemic species were 21 species (RA: 31.3%). The endangered fishes were Acheilognathus somjinensis (Level I), Lampetra reissneri (Level II) and Microphysogobio koreensis (Level II). The exotic species were Carassius cuvieri, Lepomis macrochirus and Micropterus salmoides. We supposed that Odontobutis interrupta in the Seomjin River is translocated species.

• Journal of Yeungnam Medical Science
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• v.10 no.2
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• pp.400-408
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• 1993

During the period from March 1990 to November 1993, 22 children with diplaced supracondylar fracture of humerus were treated by closed reduction and percutaneous K-wire fixation at department of Orthopaedic surgery in Yeungnam University. All fracture were treated with closed reduction under the general anesthesia and percutaneous pinning. After the fracture was internally fixed, intraoperative anteroposterior reontgenograms of each distal humerus were compared. Only anatomical reduction ensured good result, because the main cause of late cubitus varus was medial tilting of distal fragment. We could follow up 10 patients more than one year. By Flynn's criteria, satisfactory result were obtained in 9 of the 10. Unsatisfactory one had a limitation in flexion of elbow joint, but had no problem in cosmetic feature. In short term follow up of 7 patients, 5 patients had a satisfactory result, too. There were no neurovascular complication and hospitalization was shortened to 11.4 days. Closed reduction and percutaneous pinning provided stabillity, vascular safety, simplified management, reduced hospital stay. This is safe and reliable technique for obtaining and maintaining an excellent reduction.

• Journal of the Korean Arthroscopy Society
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• v.16 no.2
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• pp.114-120
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• 2012

Purpose: The purpose of the study was to evaluate the usefulness and the stability of the superficial medial collateral ligament (MCL) release in posterior medial meniscus root repair. Materials and Methods: We compared 20 patients who underwent posterior medial meniscus root repair with superficial MCL preserved (PM) and 32 patients who underwent posterior medial meniscus root repair combined with superficial MCL release (RM) from April 2006 to September 2010. We excluded the patients combined with other surgery. To evaluate the postoperative valgus instability in RM group, we examined direct tenderness on MCL insertion, the subjective feeling of instability and valgus stress test at 3 months and 1 year follow-up. We compared the tourniquet time between PM group and RM group, and the clinical results were assessed by Lysholm score and International Knee Documentation Committee (IKDC) for the usefulness. Results: All patients had no clinically significant complication related to the superficial MCL release. Three months and 1 year follow-up, there were no positive tenderness test, no subjective symptoms and no significant increase of valgus instability although 5 patients examined grade I valgus instability. The mean tourniquet time was $41.3{\pm}12.7$ minutes in RM group and $53.5{\pm}13.6$ minutes in PM group. There was a significant difference in the tourniquet time between the two groups (P<0.05). Average Lysholm score was $56.8{\pm}5.5$ (range, 44-70) preoperatively and $85.1{\pm}5.8$ (range, 77-94) postoperatively in PM group, and was $56.2{\pm}5.4$ (range, 45-67) preoperatively and $87.4{\pm}3.9$ (range, 82-95) postoperatively in RM group (P<0.001). No significant difference of Lysholm score was found in both groups (P<0.05). Average IKDC scores was $42.6{\pm}3.9$ (range, 30-53) preoperatively and $77.2{\pm}6.3$ (range, 68-92) postoperatively in PM group, and was $42.7{\pm}5.7$ (range, 30-53) preoperatively and $89.6{\pm}2.9$ (range, 84-95) postoperatively in RM group (P<0.05). There was also no significant difference of IKDC score in both groups (P<0.05). Conclusion: The superficial MCL release in posterior medial meniscus root repair is useful to gain a wide surgical field and reduces the tourniquet time and does not lead to postoperative valgus instability. It can be considered clinically useful and safe procedure in medial meniscus posterior root repair.