중유전율 LTCC 기판용 $CaZrO_3-CaTiO_3$계 세라믹스의 저온소결 및 유전특성

박정현,최영진,고원준,박재환,박재관,Park Jeong-Hyun,Choi Young-Jin,Ko Won-Jun,Park Jae-Hwan,Park Jae-Gwan 한국마이크로전자및패키징학회 2004 마이크로전자 및 패키징학회지 Vol.11 No.3

[ $CaZrO_3$ ]세라믹스에 대하여 $CaTiO_3$세라믹스의 첨가량 변동에 따른 마이크로파 유전특성을 조사하였다. 또한 중유전율 LTCC 기능성 기판으로 활용하기 위하여 저융점의 유리 프리트를 첨가하여 $CaZrO_3-CaTiO_3$ 세라믹스의 저온 소결 거동과 마이크로파 유전특성을 평가하였다. 저온 소결 조제로 사용된 저응점의 유리 프리트를 $10-20 wt\%$ 범위로 첨가함으로서 $CaZrO_3-CaTiO_3$ 세라믹스의 소결온도를 $1450^{\circ}C$에서 $900^{\circ}C$이하로 낮출 수 있었다. 음의 온도계수를 갖는 $CaZrO_3$ 및 유리프리트에 대하여 양의 온도계수를 갖는 $CaTiO_3$ 세라믹스의 분율을 적정히 제어함으로서 제로의 온도계수를 구현할 수 있었다. $CaZrO_3-CaTiO_3$ 세라믹스에 저온 소결용 유리 프리트를 $15 wt\%$ 첨가하여 $875^{\circ}C$에서 소결한 경우. 유전율(k) 23, 품질계수(Q${\times}$f) 2500, 공진 주파수 온도계수$(T_f) -3 ppm/^{\circ}C$의 매우 양호한 마이크로파 유전특성을 나타내었다. The microwave dielectric properties of $CaZrO_3$ ceramics with addition of $CaTiO_3$ were studied. The effect of glass addition on the low-temperature sintering and microwave dielectric properties of $CaZrO_3-CaTiO_3$ ceramics were also evaluated to develop the materials for functional substrates of low-temperature co-fired ceramics. When $10-20 wt\%$ of lithium borosilicate glass was added, the sintering temperature of the $CaZrO_3-CaTiO_3$ ceramics decreased from $1450^{\circ}C$ to below $900^{\circ}C$. As the $T_f$ of glass frits and $CaZrO_3$ are slightly negative and that of $CaTiO_3$ is significantly positive, zero $T_f$ could be realized by mixing an appropriate amount of $CaTiO_3$ with $CaZrO_3$. The $CaZrO_3-CaTiO_3$ ceramics sintered at $875^{\circ}C$ with $15wt\%$ glass frits showed the relative density of $98\%$, permittivity of 23, quality factor of 2500 GHz, and temperature coefficient of resonant frequency of $ -3 ppm/^{\circ}C$.

LTCC 내장 캐패시터용 BaTiO₃계 세라믹스의 저온소결 및 유전특성

박정현,최영진,고원준,박재환,남산,박재관,Park, Jeong-Hyun,Choi, Young-Jin,Ko, Won-Jun,Park, Jae-Hwan,Nahm, Sahn,Park, Jae-Gwan 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2

[ $BaTiO_3$ ]계 유전체 모재료에 대하여 $Al_{2}O_{3}$와 CaO 조성이 소량 포함된 lithium-borosilicate계 유리 프릿을 $5\~15wt\%$ 적용함으로써 LTCC용 내장 캐패시터로 적용 가능한 조성을 개발하였다. 이를 위하여 먼저, 화학적으로 안정하고 저온소성효과가 탁월한 유리 프릿 조성물을 설계하고 이를 유전체 모재료에 적용하여 저온소성특성 및 유전특성을 평가하였다. $BaTiO_3$ 세라믹스를 모재료로 하는 경우 유리 프릿을 5wt$\%$ 첨가하였을 때 $925^{\circ}C$에서 $95\%$ 정도의 상대밀도 값을 나타내었으며, 이 경우 유전율 990, 유전손실 $3.1\%$의 유전특성을 나타내었다. $(Ba,Ca)(Ti,Zr)O_3$ 세라믹스를 모재료로 하여 유리프릿을 10 wt$\%$ 첨가한 경우는 $875^{\circ}C$의 소결온도에서 상대밀도가 $95\%$ 이상이며 기공율 $0.5\%$ 이하인 소결특성을 나타내었고, 700 이상의 유전율 및 $2\%$ 내외의 유전손실 값을 가지는 것으로 측정되었다. The compositions for LTCC embedded capacitors based on $BaTiO_3$ ceramics with $5\~15\;wt\%$ of lithium-borosilicate glass frits were studied. After the glass frits, which is chemically stable and has acceptable ability of low-temperature sintering, were added to the host dielectric materials, the sintering behavior and dielectric properties were evaluated. As for $BaTiO_3$, relative density of >$95\%$, permittivity 990, and dielectric loss $3.1\%$ were obtained when sintered at $925^{\circ}C$ with 5 wt$\%$ of glass frits. As for $(Ba,Ca)(Ti,Zr)O_3$ ceramics, relative density of >$95\%$, open porosity <$0.5\%$, permittivity 700, and dielectric loss $2\%$ were obtained when sintered at $875^{\circ}C$ with 10 wt$\%$ of glass frits.

Influence of Bacterial Attachment on Arsenic Bioleaching from Mine Tailings: Dependency on the Ratio of Bacteria-Solid Substrate

박정현,최소원,김현중,Park, Jeonghyun,Silva, Rene A.,Choi, Sowon,Ilyas, Sadia,Kim, Hyunjung The Korean Institute of Resources Recycling 2021 資源 리싸이클링 Vol.30 No.3

The present study investigates the bioleaching efficiencies of arsenic via contact and non-contact mechanisms. The attachment of Acidithiobacillus ferrooxidans was restricted by a partition system comprising a semi-permeable membrane with a molecular weight cutoff of 12-14 kDa. The results were compared for two arsenic concentrations in the system (1.0% and 0.5% w/v) to maintain a homogeneous system. The overall bacterial performance was monitored by comparing total arsenic and iron concentrations, Fe ion speciation, pH, and solution redox potentials in flask bioleaching experiments over a period of 10 d. Our results indicated that bacterial attachment could increase arsenic extraction efficiency from 20.0% to 44.9% at 1.0 % solid concentrations. These findings suggest that the bacterial contact mechanism greatly influences arsenic bioleaching from mine tailings. Therefore, systems involving two-step or non-contact bioleaching are less effective than those involving one-step or contact bioleaching for the efficient extraction of arsenic from mine tailings.

재발된 누선과 안와 선양낭포암에 대한 전안와제거술 - 증례보고 -

박정현,김영수,최희윤,고용,오성훈,오석전,Park, Jeong Hyun,Kim, Young Soo,CHoi, Hee Yoon,Ko, Yong,Oh, Seong Hoon,Oh, Suck Jun 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.3

A 54-year-old woman presented with an exophthalmos and a mass on her right eye, which proved to be recurred adenoid cystic carcinoma of the lacrimal gland. Orbital CT and MRI showed that tumor was located in the right orbit, but skin over right eye brow was also involved. There was no visualization of tumor extension into the intracranial compartment. The authors have performed an en bloc orbitectomy. Although en bloc orbitectomy is known to be useful in reducing recurrence, this case showed the tumor recurrence and even distant metastasis that occurred after total tumor removal via en bloc orbitectomy. As adenoid cystic carcinoma of lacrimal gland is known to have high rate of recurrence and metastasis, en bloc orbitectomy should be performed to reduce local advancement and distant metastasis. In case of distant metastasis, radiotherapy could be useful strategy in selected case.

OSS 활용 고려사항과 검증 방법

박정현,박영식,김현기,김영길,Park, J.H.,Park, Y.S,Kim, H.K.,Kim, Y.K. 한국전자통신연구원 2019 전자통신동향분석 Vol.34 No.1

In this paper, we focus on the process of using open source software (OSS) and factors that should be considered when using project-based OSS. We also elaborate on how to avoid using OSS licenses in an OSS-based technology development process, why dual OSS licenses and security threats should be avoided, and the method of notification after use. In addition, the OSS license verification method and environment are described in the course of project development. In the verification method, the OSS license used for technology development in the course of project execution is validated in advance by the person who decides whether or not to use the OSS, and then additional verification using the tool after technology development. It is expected that this paper will be helpful for establishing the OSS usage consideration and the license verification procedure, and environment in the future.

RFID 기술 수준과 도입 사례

박정현,Park, J.H. 한국전자통신연구원 2006 전자통신동향분석 Vol.21 No.3

우편 물류 환경에 RFID 기술을 도입하는 경우 가장 먼저 기대할 수 있는 효과는 비용절감이다. 두번째는 우편 물류 처리시간의 단축과 이로 인한 우편물 처리 용량의 증대효과이다. 본 고에서는 우편 물류 환경에서 RFID 기술 도입 시 그 시행 착오를 줄이고 보다 효율적인 RFID 기술 도입을 위해 현재의 RFID 기술 수준을 파악하고, 국내외RFID 기술 도입 사례를 제시한다. 이를 위해 현재의 RFID 기술에 대한 국제 표준화 상황과 RFID 기술 상용 제품의 가격과 성능 수준 그리고 RFID 기술 도입 사례 등을 기술한다.

수포각막병증에서 양막 이식술의 효용성

박정현,정진욱,위원량,이진학,김미금,이재림.Jung Hyun Park. M.D.. Jin Wook Jeoung. M.D.. Won Ryang Wee. M.D.. Ph.D... Jin Hak Lee. M.D. Ph.D... Mee Kum Kim. M.D.. Ph.D... Jae Lim Lee. M.D. 대한안과학회 2007 대한안과학회지 Vol.48 No.8

Purpose: To evaluate the efficacy of amniotic membrane (AM) transplantation in symptomatic bullous keratopathy using cryo-preserved or lyophilized AM. Methods: Eight bullous keratopathic patients, who experienced intractable pain despite medication and the application of a therapeutic lens, underwent permanent AM transplantation with 5 cryo-preserved and 3 lyophilized AMs following removal of epithelium using a trephine. The time to re-epithelization and the subsidence of pain were evaluated retrospectively. Results: Mean follow-up was 252±171.0 days. Pain relief and re-epithelization were obtained in all eight patients. The times to complete relief of pain was 32.2±22.7 days in patients with cryo-preserved AM transplantations (n=5) and 22.0±18.0 days in those with lyophilized AM transplantations (n=3) (p=0.549, Mann-Whitney U test). Respective times to re-epithelization were 25.4±20.7 days and 23.0±25.2 days (p=0.297). There were no significant differences in the diameter of transplanted AMs between the two groups (7.6±0.2 vs. 7.3±0.3 mm, p=0.172). Conclusions: Permanent AM transplantation effectively reduced the intractable pain caused by epithelial bulla. Whether the AM was cryo-preserved or lyophilized did not affect the efficacy of the treatment.

원인미상의 윤부염을 동반한 T-세포 매개 만성 결막염을 경구 사이클로스포린으로 완치한 1예

박정현,위원량,이진학,김미금,ung Hyun Park,Won Ryang Wee,Jin Hak Lee Ph,D,Mee Kum Kim 대한안과학회 2007 대한안과학회지 Vol.48 No.11

Purpose: To report a case of refractory idiopathic T cell mediated chronic conjunctivitis causing limbal insufficiency, which improved with cyclosporine therapy. Case Summary: A 43-year old man complained of conjunctival injection and discomfort in both eyes that lasted three years and was refractory to topical steroids, antibiotics, and artificial tears. There was no evidence of connective tissue diseases, Stevens-Johnson syndrome, pemphigoid, or drug history. Both eyes presented with diffuse injection and thickening of the conjunctiva, punctuated epithelial erosion of the conjunctiva and cornea, severe limbal epithelitis and elevated intraocular pressure. The left cornea was conjunctivalized due to limbal deficiency. Histological examination revealed severe infiltration of T and B cells, without any evidence of tumor cells or basement membrane anomaly. When treated with oral cyclosporine, injection and thickening of the conjunctiva decreased and the intraocular pressure was normalized. The surface inflammation of both eyes completely resolved two months after the treatment was initiated. Conclusions: In chronic idiopathic conjunctivitis with limbitis resistant to conventional treatment and T cell infiltration found in pathological examination, oral cyclosporine therapy might be required to resolve inflammation.

치과용 임플란트 적용 비귀금속 코어와 관련된 전조골세포의 변화

박정현,강신영,김종우,김장주,김웅철,김지환,Park, Jung-Hyun,Kang, Seen-Young,Kim, Jong-Woo,Kim, Jang-Ju,Kim, Woong-Chul,Kim, Ji-Hwan 대한치과기공학회 2018 대한치과기공학회지 Vol.40 No.2

Purpose: The purpose of this study is to investigate the non-precious metal core materials used in the dental laboratory to fabricate the implant superstructure by CAD / CAM method. And to observe and compare the morphology and distribution of the osteoblasts in relation to implant osseointegration. Methods: In this study, the mandibular right first molar tooth model was selected as an international standard to produce a single core. Using this model, the impression was made with the silicone rubber, the tooth model was scanned, and a single core was designed and 5-axis milling was performed. The materials used were Cobalt-Chromium and Nickel-Chromium, and the cores for dental implant top structures were fabricated according to the procedures of the dental labs. After the fabrication, the marginal area of the core was separated and cell culture experiment was performed. The osteoblast cells used MC3T3-E1, which is currently widely used. For morphological analysis of osteoblasts, cells were posttreated and observed using CLSM (Confocal Laser Scanning Microscope) and compared. Results: The cell adhesion behavior of the specimen surface measured by CLSM was uniformly distributed in specimen A (Cobalt-Chromium) than in specimen B (Nickel-Chromium). The distribution and changes of the cells were different in the two specimens. Conclusion : It is possible to confirm that specimen A (Cobalt-Chromium) is suitable for the living body through adhesion and proliferation of osteoblasts related to implant osseointegration in the non-precious metal superstructure used after implantation. It is considered that it is preferable to use Co-Cr when fabricating the superstructure.

미숙아에서의 24시간 식도 PH 검사

박정현,박범수,Park, Jeung-Hyun,Park, Beom-Soo 대한소아소화기영양학회 2001 Pediatric gastroenterology, hepatology & nutrition Vol.4 No.2

위식도역류는 영아들에 있어서 흔하게 있다고 알려져 있고 특히 미숙아들에게 더 흔히 있다고 알려져 있지만 아직 이에 대한 연구는 부족하다. 목적: 건강하게 자라고 있는 미숙아들에게 위식도역류의 진단에 가장 예민하다고 알려져 있는 24시간 식도 pH 검사를 통하여 그 빈도 및 연관 인자를 찾고자 하였다. 방법: 특이 증상 없이 건강하게 자라고 있는 미숙아 21명(평균 재태기간: $30+{\pm}2+0$주, 출생시의 평균 체중은 $1,468{\pm}329$ g, 검사 당시의 평균 나이는 $29{\pm}8$일, 수태 후 나이(Postconceptional age: 재태기간+출생 후 나이)는 $34+6{\pm}1+4$주, 체중은 $1,750{\pm}329$ g, 남아 : 여아=15:6)을 대상으로 휴대용 레코더가 연결되어 있는 실리콘 재질의 마이크로 소식자를 Stobel의 공식($0.252{\times}$키+5 (cm))에 따라 코로 넣어 그 거리만큼 식도내강에 위치시킨 후 거리를 교정하여 24시간 동안 식도 pH 검사를 시행하였다. 결과: 네 가지 파라미터(number of acid reflux, number of long acid reflux (5 min), longest acid reflux minutes, RI)를 제시하였고 전체 대상환아의 57%에서 유의한 위식도역류가 있음을 보였다. 위식도역류와 number of acid reflux, RI의 두 파라미터가 통계적으로 의미있는 상관관계를 보였으며 이 두 파라미터와 Reflux index of the postprandial 120 min간에도 의미있는 상관관계가 있음을 알 수 있었다. 위식도역류가 있는 환아들을 출생체중, 재태기간, 검사 당시의 나이, 수태 후 나이, 체중, 성별 및 테오필린(theophylline) 투약 여부에 따라 각각 구분하여 그 차이를 살펴보았고 모두 통계학적으로 큰 차이는 없었다. 소식자의 거리는 Stobel의 공식에 의한 거리와 실제길이 사이에 차이가 있어 우리의 미숙아의 경우에는 $0.252{\times}$키+3.7 (cm)로 적용시킬 수 있었다. 결론: 위와 같은 결과로 미숙아들에게 있어서 무증상적, 유의한 위식도역류가 57%의 높은 빈도로 나타났고, 위식도역류증의 진단에 가장 중요한 파라미터는 number of acid reflux, RI와 Reflux index of the postprandial 120 min로 나타났다. 출생체중, 재태기간, 검사 당시의 나이, 수태 후 나이, 체중 및 성별, 테오필린 투약여부 등과 위식도역류와는 통계적으로 유의성이 없었다. 또한 1세 이하의 영아에게 소식자의 위치를 정하는데 사용되는 Strobel의 공식을 본 연구대상 미숙아들에게 적용해본 결과 소식자의 위치가 $0.252{\times}$키+3.7(cm)로 나타났다. Purpose: Gastroesophageal reflux (GER) has been found to be the causative factors of apnea, stridor, feeding intolerance, poor weight gain, and sudden infants death syndrome (SIDS) in infants. GER is a well-described in infants and children, but only scant mention of the premature infants with GER can be found in the literature. Methods: Esophageal pH was measured during 24 hour in 21 healthy preterm infants, using a silicone microelectrode with an external reference electrode connected to a portable recorder. The mean age of the patients was $29{\pm}8$ days, mean gestational age was $30^{+5}{\pm}2^{+0}$ weeks, mean birth weight was $1,468{\pm}329$ g, mean postconceptional age was $34^{+6}{\pm}1^{+4}$ weeks and mean weight was $1,750{\pm}329$ g. We evaluated the following reflux parameters; number of acid reflux, number of long acid reflux, longest acid reflux minutes, and reflux index. Results: Pathologic GER was detected in 12 (57%) subjects and most interesting parameters are reflux index and number of episodes with a pH<4 during 24 hour (high correlation with postprandial reflux index). Reflux was not correlated to gestational age, birth weight, age, postconceptional age, weight, sex and medication of the theophylline. Conclusion: Gastroesophageal reflux is common in preterm infants, but it is usually not apparent, even with severe reflux.