마이크로파 소결법을 이용한 Bi_0.5Na_0.5TiO₃계 적층형 세라믹 액추에이터 제조

강진규,이재신,Kang, Jin-Kyu,Lee, Jae-Shin 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.11

A comparative study has been attempted for microwave and conventional sintering of lead-free $Bi_{0.5}Na_{0.5}TiO_3(BNT)$-based multilayer ceramic actuators(MLAs). It was found that microwave sintering (MWS) could be successfully applied to the co-firing of piezoceramic/AgPd MLAs with a 10 times shorter firing cycle as well as $100^{\circ}C$ lower firing temperature ($850^{\circ}C$) for sufficient densification than conventional furnace sintering ($950^{\circ}C$). Furthermore, MWS-derived specimens showed better electric field-induced strain than that of CFS-derived specimens by effectively suppressing interdiffusions between ceramic and electrode layers.

근막동통으로 인한 하악 구치부 연관통의 임상증례

강진규,Kang, Jin-Kyu 대한안면통증구강내과학회 2007 Journal of Oral Medicine and Pain Vol.32 No.4

Majority of toothache is caused by abnormality of pulpal or periodontal tissues. However, there are numerous nonodontogenic sources that may be responsible for pain felt in the tooth. Nonodontogenic toothache may result from muscle, maxillary sinus, neuropathic, neurovascular, even cardiac and psychogenic problems. Myofascial pain is one of the most common abnormality characterized by palpation of a hard band which acts as the trigger point that causes stiffness and fatigue of the muscle, referral pain in tooth, tension-type headache, and hyperalgesia. Masseter muscle particularly induce referral pain in maxillary and mandibular molars. This case reported the treatment of the pain in right mandibular molar originated from myofascial pain of the right masseter. The pain is improved by general and reversible treatments such as muscle exercise, physical therapy, and medication. Nonodontogenic toothache should undergo proper differential diagnosis in order to avoid unnecessary dental treatments, such as endodontic, periodontic treatment, and tooth extraction, which would fail to alleviate the symptom of the patient.

(K_0.5Na_0.5)NbO₃ 세라믹스의 압전 특성에 대한 Ta 도핑 효과

강진규,이용희,허대준,이현영,딘치힌,이재신,Kang, Jin-Kyu,Lee, Yong-Hui,Heo, Dae-Jun,Lee, Hyun-Young,Dinh, Thi Hinh,Lee, Jae-Shin 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.5

We investigated the effect of Ta doping on the dielectric and piezoelectric properties of lead-free $(K_{0.5}Na_{0.5})NbO_3$ ceramics prepared using a conventional ceramic processing. X-ray diffraction analysis revealed that Ta was perfectly substituted into Nb-sites in the range of 0 to 20 at%. As Ta content in the KNN increased, the sinterability of KNN ceramics was significantly degraded while the Ta doping enhanced the piezoelectric constant $d_{33}$, planar mode piezoelectric coupling coefficient ($k_p$), and electromechanical quality factor ($Q_m$). The highest values for $d_{33}$, $k_p$, and $Q_m$ was found to be 156 pC/N, 0.37, and 155, respectively.

구강안면통증 환자에서의 두통 양상의 분류

강진규,유지원,김성택,최종훈,Kang, Jin-Kyu,Ryu, Ji-Won,Kim, Seong-Taek,Choi, Jong-Hoon 대한안면통증구강내과학회 2006 Journal of Oral Medicine and Pain Vol.31 No.4

Headache is a common disease which influences not only individually but also socially. Temporomandibular disorders(TMD) refers to pain and dysfunction within the temporomandibular joint(TMJ) and associated muscles. TMD is presented commonly, and 70% of population are found to have one or more related symptom. A number of studies have been conducted to verify the association between headache and TMD, and some authors have proposed that headache and TMD may be related. In this study, we studied the patterns of headache presented by the patients who visited the TMJ and Orofacial pain clinic. Among the patients participated in this study, tension type headache showed the highest prevalence(48.5%), followed by migraine without aura(15.0%), probable migraine(10.6%), migraine with aura(7.1%), probable tension type headache(4.8%), and other primary headaches(1.8%). The high prevalence of tension type headache may be due to the accompaniment of orofacial pain by pericranial muscle tenderness. Comparison of sex showed that the rate of migraine was higher in female than male(female to male ratio 35.8:25.3). In age analysis, the rate of migraine was high in the twenties(42.2%) and the thirties(40.0%). As the age increased, the rate of migraine decreased, and this trend was in accordance with the previous studies. The percentage of the patients who had previously received treatment was only 26.2%, and that of those who were aware of the diagnosis was merely 8.7%. Therefore, it is not common for headache patients to get treatment, however, since orofacial pain is often accompanied by headache, more systematic diagnosis as well as precise treatment would be necessary. Moreover, since TMD could induce and aggravate headache, proper evaluation and management of TMD would be essential for diagnosis and treatment of headache. In the future, more systematic and broad investigation on the influence of causative factors of TMD on headache as well as the change in headache pattern with the treatment of TMD would be required.

Bi_0.5(Na_0.82K_0.18)_0.5TiO₃ 세라믹스의 소결거동 및 압전 특성에 대한 과잉의 CuO 첨가 효과

강진규,장현덕,허대준,이현영,안경관,이재신,Kang, Jin-Kyu,Jang, Hyun-Deok,Heo, Dae-Jun,Lee, Hyun-Young,Ahn, Kyoung-Kwan,Lee, Jae-Shin 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.6

We investigated the effect of excess CuO on the sintering behavior, ferroelectric, and piezoelectric properties of lead-free $Bi_{0.5}(Na_{0.82}K_{0.18})_{0.5}TiO_3$ (BNKT) ceramics. The addition of excess CuO was found to greatly contribute to the densification and grain growth, however, excess CuO over 3 mol% was precipitated at grain boundaries after sintering. BNKT with 1~2 mol% CuO in excess sintered at $975^{\circ}C$ showed piezoelectric properties comparable to those of unmodified BNKT sintered at $1,175^{\circ}C$. These results seem meaningful for its application to low cost multilayer actuators (MLAs) because low firing ceramics make it possible to apply less expensive base metals to the inner electrode of MLAs.

Association between Sleep Quality and Psychologic Factors among University Students in Korea

강진규,임현대,이유미,Kang, Jin-Kyu,Lim, Hyun-Dae,Lee, You-Mee Korean Academy of Orofacial Pain and Oral Medicine 2008 Journal of Oral Medicine and Pain Vol.33 No.3

The mentophysical disease causes diseases in digestive, respiratory, circulating systems, including chronic pain, through combined reactions from different individual characteristics, mental stress and temperamental factors. The most common symptom related to orofacial area is pain and the contributive factors include biological, behavioral, environmental, social, emotional, recognitive factors. These factors affect the course of the symptom according to individual's character and human nature. In pain, sleep acts as a contributive factor, and pain could bring about sleep disturbance and vice versa. Deterioration of sleep quality would act as a factor that aggravates mental stress. Therefore, relatively accurate and simple mental examinations and sleep quality test should be carried out for the patients with symptoms related to orofacial area. This study evaluated the mental state in relation to the sleep quality which could affect orofacial pain. The number of poor sleeper was 18 in male subjects, and 1 in female subjects and PSQI global index was higher in male($6.11{\pm}2.38$) than female($4.67{\pm}2.18$). SCL-90-R index showed no sex difference. Poor sleeper showed significantly high value in SOM, O-C, I-S, ANX, PHOB, PSY, GSI, PST. When SCL-90-R T scores were compared according to sleep quality, higher the subjective sleep quality score, O-C and I-S showed significant increase. As sleep disturbances score increased, PAR, PSY, PST showed statistically significant increase. In comparison of SCL-90-R T score according to daytime dysfunction, statistically significant increase in DEP, ANX, HOS, PHOB, PAR, GSI was observed. Therefore, the quality of sleep and psychological status have a high correlation. This is likely to influence chronic pain in the orofacial field. As a result, clinicians treating orofacial pain should evaluate the sleep quality and psychological status of the patient. Further studies of larger sample sizes including various age, occupation, and pain groups are necessary in order to apply the results to clinical practice.

구개에 발생한 혈관성 평활근종의 보고

강진규,윤정훈,심영주,Kang, Jin-Kyu,Yoon, Jung-Hoon,Shim, Young-Joo 대한안면통증구강내과학회 2013 Journal of Oral Medicine and Pain Vol.38 No.2

평활근종(leiomyoma)은 평활근에서 발생하는 양성종양으로, 두경부 영역에서는 흔치 않은 질환이다. 구강내 평활근종의 경우 혈관성 평활근종이 가장 흔하다. 구강내 혈관성 평활근종은 비교적 단단하고, 매끈한 표면을 가지며, 경계가 명확하고, 둥글고 돌출되어 있다. 대부분 무통성으로 느리게 성장하기 때문에 환자가 병원을 찾게 될 때까지 수개월에서 수년이 걸리며, 병력 및 임상검사, 방사선학적으로 특징적인 소견을 나타내지 않아 수술 후 병리조직학적 소견으로만 진단이 가능하다. 본 증례는 구개부에 연성종양을 주소로 내원한 53세의 여자 환자에서 종양 적출술을 시행, 병리조직학적으로 혈관성 평활근종으로 확진된 1예를 문헌고찰과 함께 보고한다. Leiomyoma is benign neoplasm of smooth muscle, but it is rare in the oral cavity. The most common type of leiomyoma in the oral cavity is vascular leiomyoma. Clinically, vascular leiomyoma usually grows slowly and is generally a small, painless, sessile, firm and superficial nodule like lesion, and the length of time before patients seek medical attention may span months to years. The diagnosis of oral leiomyoma is possible with only histological studies with special stains because there are no specific clinical and radiological signs. We experienced a 53-year-old woman with palatal mass. She underwent surgical excision and the final pathological result confirmed it to be vascular leiomyoma. We report this case with a review of the related literatures.

암모늄 기능화 메조다공성 실리카의 인산염 흡착

강진규 ( Jin-kyu Kang ),이창구 ( Chang-gu Lee ),박정안 ( Jeong-ann Park ),최재우 ( Jae-woo Choi ),이상협 ( Sang-hyup Lee ),김성배 ( Song-bae Kim ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-

본 연구에서는 수환경상에서 녹조발생의 제한요소인 인의 효과적인 제거를 위하여 암모늄 기능화 메조다공성 실리카를 합성하여 인 흡착특성을 살펴보았다. 이를 위하여 메조다공성 실리카인 MCM-41을 합성 후 이에 실란커플링제인 3-aminopropyltrimethoxysilane (APTMS)를 이용하여 아민기를 표면에 도입하였으며, 이를 다시 HCl로 산처리하여 아민기에 양자를 가하여 암모늄 기능화 메조다공성 실리카를 합성하였다. 준비한 흡착제의 흡착특성을 평가하기 위하여 인산염을 대상으로 Pseudo first-order, Pseudo second-order, Elovich 등의 모델을 통하여 동적 회분실험을 평가하였으며, Langmuir, Freundlich, Redlich-Peterson 등의 모델을 통하여 등온 평형 회분실험을 평가하였다. 동적 회분 실험의 분석결과 Pseudo second-order 모델로 가장 잘 설명되는 것으로 나타났다. 이때 평형 흡착량은 1.858 mg/g이며 pseudo-second-order 속도 상수는 183.98 g/mg/min이다. 또한 등온 평형 회분실험의 분석결과는 Redlich-Peterson모델로 가장 잘 설명되는 것으로 나타났다. 이때 Redlich-Peterson 등온흡착 상수인 K_RP와 α_RP는 각각 590.0 L/g, 79.5 L/mg으로 나타났으며 β는 0.775로 나타났다.

CZT(S,Se) 태양전지 연구 현황 및 전망

강진규 ( Jin-kyu Kang ),손대호 ( Dae-ho Son ),심준형 ( Jun-hyoung Sim ),황대규 ( Dae-kue Hwang ),성시준 ( Shi-joon Sung ),양기정 ( Kee-jeong Yang ),김대환 ( Dae-hwan Kim ) 한국공업화학회 2017 공업화학전망 Vol.20 No.2

태양전지는 온실 가스 감축에 효과가 큰 기후 변화 대응 기술이다. 현재 상업화에 성공한 실리콘 태양전지의 뒤를 이어 박막 태양전지, 페로브스카이트 태양전지 등 차세대 태양전지가 가격과 효율 등을 극복하기 위하여 매우 많이 연구되고 있다. CZT(S,Se) 박막 태양전지는 차세대 태양전지의 유력 후보군인 CIGS, CdTe, 페로브스카이트 태양전지 등에 비해 범용 무독성 원소를 광흡수층으로 사용한다는 장점을 가지고 있지만 아직까지는 이들보다 효율이 낮아 상용화하기에는 많은 문제를 가지고 있다. CZT(S,Se) 박막태양전지의 기본적인 물성, 공정 등을 알아보고 고효율을 달성하는 방법에 대하여 알아보고자 한다.

사급암모늄 기능화된 실리카겔의 흐름조건에서의 질산이온 제거 특성 평가

강진규 ( Jin-kyu Kang ),박정안 ( Jeong-ann Park ),이승찬 ( Seung-chan Lee ),장호영 ( Ho-young Jang ),최낙철 ( Nag-choul Choi ),조강희 ( Kang-hee Cho ),김성배 ( Song-bae Kim ) 한국농공학회 2019 한국농공학회 학술대회초록집 Vol.2019 No.-

본 연구에서는 사급 암모늄 기능화된 실리카겔을 이용하여 흐름 조건에서의 수중 질산성 질소에 대한 선택적 제거특성을 평가해보고자 하였다. 이를 위하여 실리카 겔의 표면을 dimethyloctylamine 등을 바탕으로 기능화하여 사급 암모늄기를 부여하였다. 이를 이용하여 수중 질산성 질소에 대한 선택적 제거 특성을 평가하기 위하여 다양한 경쟁 음이온과 또한 실제 반류수를 바탕으로 전처리를 수행하여 유기물 등의 영향을 최소화한 조건에서 칼럼실험을 수행해보았으며, 이를 통해 사급 암모늄 기능화된 실리카겔이 흐름조건에서 질산이온을 선택적으로 제거 할 수 있음을 확인하였다.