• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.322-328
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• 2007

The first molar is important for mastication and also it plays roles to formation of vertical occlusion and growth of jaw bone after mixed dentition. Impaction of mandibular first molar can result in a short lower facial height, formation of a follicular cyst, pericoronal inflammation, resorption of the roots of neighboring teeth and malocclusion. The options of treatment plans are as follows; observation, surgical exposure, orthodontic traction, surgical relocation and extraction. Surgical exposure could be considered as a basic treatment plan. For surgical exposure it is important to maintain patent channel between the crown and the normal eruptive path into the oral cavity, many techniques including cementation of a celluloid crown, packing with zinc oxide-eugenol surgical pack are used. In these cases, we could observe spontaneous eruption of mandibular first molar using surgical exposure with or without removal of odontoma. Also we could obtain the main patency effectively and conveniently by using surgical pack and translucent retainer.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.18-29
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• 2008

The purpose of this study was to compare the polymerization shrinkage of several filling methods using strain gauges. In this study, a light-emitting diode(LED) curing unit(Elipar Freeligh2, 3M EPSE, USA) and plasma arc lamp(PAL) curing unit(Flipo, LOKKI, France) were used for curing, Filtek $Z350^{TM}$(3M EPSE, USA) composite resin was used for the cavity filling. Sixty permanent bicuspid teeth, that were extracted for orthodontic treatment, were studied. The cavities were prepared on the occlusal surface and were filled using the following methods : 1) bulk filling, 2) parallel filling, 3) oblique filling The strain was recorded on the buccal, lingual, mesial and distal surfaces and the strain values were computed into stress values. The shear bond strength of each filling method was tested using a Micro Universal Testing machine. The results can be summarized as follows: 1. In the strain changes, all LED and PAL curing groups showed an increase on the buccal surface and a slow decrease as time elapsed. 2. In the strain changes of the mesial and distal surfaces, the decreases and increases were shown repeatedly and reduced as time elapsed. 3. There were no significant statistical strain changes among filling methods in the LED or PAL curing groups. 4. There were significant statistical strain changes between the LED and PAL curing groups on the buccal surface(p<0.05). 5. From the shear bond strength results, in the LED curing group, filling method 3 showed lower surface stress than filling method 1 and 2(p<0.05). In the PAL curing group, there were no significant statistical strain changes between each filling method. 6. The surface stress of each group was lower than the shear bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.456-463
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• 2009

Cleidocranial dysplasia(CCD) is a congenital disorder of skeletal and dental abnormality, which is a mesodermal dysfunction influencing many tisssues and organs. Skeletal abnormalities in CCD are delayed closure of cranial suture and fontanelle, presence of wormian bone and clavicle aplasia. CCD also has an effect on long bones, phalanges, spine, pelvis, muscles, and central nervous system. Dental manifestations include retention of deciduous teeth, multiple supernumerary teeth, delayed eruption or impaction of permanent teeth and formation of cysts around nonerupted teeth. However, due to lack of any substansive medical or physical disability, diagnosis is often late, thereby causing masticatory and psychological problems caused by delayed eruption of permanent teeth after exfoliation of deciduous teeth. For this reason, CCD requires early diagnosis, and the patient's appearance must be improved. Also, provision for a functional masticatiory mechanism by treatment of surgical removal of supernumerary teeth followed by orthodontic eruption of the natural permanent teeth at an adequate time is necessary.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.412-419
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• 2009

The purpose of this study was to provide the reference data evaluating the treatment effect of orthopedic appliances. The skeletal and dental growth increments were measured in 24 normal mixed dentition children (boys: 14, girls: 10) by three serial lateral cephalograms: initial mean age: 9${\pm}$1.3 years, mean observation period: 13${\pm}$1.3 months. Cephalometric changes were analysed. The results were as follows: 1. In boys, the maxilla showed forward and downward growth pattern and the mandible showed forward growth pattern (p<0.05). In girls, the maxilla and mandible showed forward and downward growth pattern(p<0.05). 2. Horizontal growth of both maxilla and mandible in girls was superior to those in boys (A point; girls: 2.39mm, boys: 1.26mm, with p<0.05), whereas vertical growth of both maxilla and mandible in boys was similar to those in girls. 3. The change in tooth axis showed labioversion of upper incisor (p<0.01) and comparatively stable lower incisor position.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.532-538
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• 2008

Lesch-Nyhan syndrome is a rare X-linked recessively inherited disorder, caused by complete absence or decrease in activity of hypoxanthine guanine phosphoribosyl transferase(HPRT), an enzyme involved in purine metabolism. This enzyme deficiency gives rise to nephropathy symptoms, such as hyperuricosuria and hyperuricemia by excessive uric acid production and neuropathy symptoms, such as mental retardation, choreoathetosis and self mutilation behavior. Patients with Lesch-Nyhan syndrome have tendency to bite their lip, tongue and finger. In severe cases, partial or even total amputation of tongue or finger occur. Self-inflicted bites are often complicated by secondary infection to the injured site as well as pain. Furthermore tissue loss by biting results in esthetic problems. The dental management of self mutilation includes treatment with appliances such as soft mouth guard or lip bumper, extraction of all the teeth, and orthognathic surgery. We report a case of a 13 year-old boy with Lesch-Nyhan syndrome, who severely injured himself on his tongue. At first, conservative treatment using soft mouth guard was considered, but it could not prevent trauma on his tongue. Therefore, extraction of the lower anterior and posterior teeth was carried out.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.17-24
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• 2020

The purpose of this study was to evaluate the accuracy and precision of the three-dimensional (3D) imaging system of children's facial soft tissue by comparing linear measurements. The subjects of the study were 15 children between the ages of 7 and 12. Twenty-three landmarks were pointed on the face of each subject and 16 linear measurements were directly obtained 2 times using an electronic caliper. Two sets of 3D facial images were made by the 3D scanner. The same 16 measurements were obtained on each 3D image. In the accuracy test, the total average difference was 0.9 mm. The precision of 3D photogrammetry was almost equivalent to that of direct measurement. Thus, 3D photogrammetry by the 3D scanner in children had sufficient accuracy and precision to be used in clinical setting. However, the 3D imaging system requires the subject's compliance for exact images. If the clinicians provide specific instructions to children while obtaining 3D images, the 3D device is useful for investigating children's facial growth and development. Also the device can be a valuable tool for evaluating the results of orthodontic and orthopedic treatments.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.14 no.2
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• pp.238-246
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• 2003

Objectives：Mental health problems have been found to be more common among juvenile delinquents. This report assessed the reliability, and validity of the MAYSI-2K(Massachusettes Youth Screening Instrument-2 Korean) in Korean delinquents to examine the utility as a screening measure. Methods：The study consisted of 119 male juvenile youths(mean age 16) who admitted in the probation & detention office. They completed an assessment battery including MAYSI-2K and K-YSR(Korean-Youth Self Report) upon entry. Factor analysis, reliability test, and validity test were conducted. Results：The results of factor analysis represented 14 factors which showed more factor structures in comparison with published factor loadings of 7 in the MAYSI. In factor analysis according to the each subscale of the MAYSI, the internal coefficients of 7 subscales ranged from .142 to .756. Test-retest reliability revealed significant correlations(r= .84). There were significant correlations among subscales of MAYSI-2K and K-YSR. Conclusion：Our findings suggested that MAYSI-2K might be a useful screening measure. But further studies with extended number of subjects and culturally appropriate items are required for clinical utility of the MAYSI-2K in Korean delinquents.

• Radiation Oncology Journal
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• v.7 no.1
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• pp.85-92
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• 1989

Dosimerty based on electron spin resonance (ESR) analysis of radiation induced free radicals in amino acids is relevant to biological dosimetry applications. Alanine detectors are without walls and are tissue equivalent. Therefore, alanine ESR dosimetry looks promising for use in the therapy level. The dose range of the alanine/ESR dosimetry system can be extended down to 1 Gy. In water phantom the absorbed dose of electrons generated by a medical linear accelerator of different initial energies $(6\~21MeV)$ and therapeutic dose levels (1~60 Gy) was measured. Furthermore, depth dose measurements carried out with alanine dosimeters were compared with ionization chamber measurements. As the results, the measured absorbed doses for shallow depth of initial electron energies above 15 MeV were higher by$2\~5\%$ than those calculated by nominal energy $C_E$ factors. This seems to be caused by low energy scattered beams generated from the scattering foil and electron cones of beam projecting device in medical linear accelerator.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.132-132
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• 2000

환경오염과 이상기후의 영향으로 인한 수자원의 고갈과 함께 국내의 경우 수자원 개발 계획 및 수요량을 감안할 때 향후 7 년 내에 물부족 현상을 겪을 것이라는 보고가 있 었으며, 환경부담을 줄이기 위해 폐수의 배출기준은 강화되고 있다. 이러한 상황에서 제조 특성상 타 업종에 비해 폐수 발생량이 높은 편인 국내의 제지산업은 여러 해전부터 이에 대 한 방안을 모색하여 왔다. 일반적으로 폐수 수질 관리와 청수 사용량의 절감을 위해 고가의 폐수 처리 장치를 설치하거나 폐수 재활용을 통해 공정을 극도로 폐쇄화하는 방안으로 연구 가 진행되어 왔다. 이 중 용수의 재활용이 가장 경제적인 방법이지만, 재활용이 지속될수록 각종 무기염과 콜로이드성 유기물질이 축적되어 각종 약품의 효능 저하, 탈수속도의 저하 및 생산 제품의 품질 악화 등의 문제를 유발한다고 알려져 있다. 이를 해결하고자 하는 노 력으로 펄프 원료에 따른 공정수 내 용해성 물질의 분석과 재활용 횟수에 따른 각종 SS와 D DS의 축적 정도에 대한 기초 연구가 수행되었으며, 고폐쇄화된 공정에서 성능을 발휘할 수 있는 첨가제의 개발과 적용 방법에 대한 연구도 수행된 바 있다.여러 지종 가운데 골판지 원지는 용수의 재활용률이 상당히 높은 지종이기 때문에 공정수의 재활용이 진행될수록 열악한 저급 원료로부터 각종의 다양한 물질이 용출 혹은 배 출되며, 이러한‘물질은 골판지 원지의 강도 발현에 더욱 악영향을 미칠 것으로 판단되었다. 미세분으로 구성된 SS의 경우 이미 많은 연구를 통해 특성이 파악되었기 때문에 본 연구에 서는 ss를 제외한 공정수를 두 가지로 크게 나누어 고려하였다. 즉, ss로 측정되지 않지만 닥도를 유발할 수 있는 미세 무기물질과, 용해성의 무기염, 첨가제 및 추출물 둥으로 이루어 진 용해성 성분으로 나누어 분석하였으며, 또한 각각이 초지 특성에 미치는 영향을 살펴보 고자 하였다.을 해석코자 하였으며, 그 방법으 로 수치해석기법을 도입하였다. 또 실제 캘린더링 전후의 두께 변화를 측정하여 유리전이온도 의 도달 깊이와 비교하였다. 지필의 압축 정도는 롤의 직경과 닙 폭을 이용하여 MD 방향으 로 함수화하였으며, 열전달 계수로는 겉보기 값을 사용하였다. 이때 지펼은 균질한 것으로 가 정하였다. 함수율은 유리전이온도를 좌우하는 가장 큰 인자이나 본 연구에서는 항온항습처리 를 통해 유입지의 함수율을 고정시켰으며 캘린더링 시 함수율의 변이는 없다고 가정하였다. 그 결과 열침투깊이가 증가할수록 지필은 보다 변형되기 쉬운 상태가 되어 주어진 압력 조건에 대해 소성변형 정도가 증가하는 것으로 나타났다. 이는 캘린더링 전후에 두께 변화를 측정하여 정량적으로 평가할 수 있었다. 수치해석기법을 통해 같은 압력 조건에서 온도가 증 가함에 따라 혹은 같은 온도 조건에서 압력이 증가함에 따라 지필 내의 유리전이온도의 침투 깊이가 증가함을 알 수 있었으며 이는 캘린더링 전후의 두께 변화의 측정 결과와 일치하였 다. 또 NRT가 증가함에 따라서도 유리전이온도 침투 깊이가 증가하였다.합편에 비해 일부 우수한 양상을 보였지만 본 실험의 범위내에서는 통계적 정량적 차이를 제시할 수는 없었다. 향후 보다 광범위한 동물 실험이 필요할 것으로 사료된다.된다.하고도 완전교정술 도달 확률이 높은 치료전략이라는 사실을 입증하였으며 주대동맥폐동맥혈관부행지의 크기나 숫자가 단일화하기 쉬운 형태학적 특징을 지닌 경우에는 조기에 일단계완전교정술을 시행하여 양호한 결과를 얻을 수 있다는 사실을 발견하였다. 반면 본 환아군 중 단일화술을 먼저 시도한 군에서는 비록 단계적인 단일화를 시도한 군에서 단일화술과 관계된 수술사망율이 약간 낮기는 하였으나 완전교정술까지 완료될 가능성에는 차이가 없었다. 그러나 이 경우 보다 정련된 적응 환자의 선택을 통한 단일화 우선전략의 시도와 장기 추

• The Journal of the Korean bone and joint tumor society
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• v.11 no.1
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• pp.100-104
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• 2005

Osteosarcoma is the most common tumor in malignant bone tumors. The peak age incidence in osteosarcoma is between 10 to 14 years of age. This tumor rarely develops under 6 years of age and the youngest patient in the previous literature was a 13 months old girl who had an osteosarcoma involving the second metacarpal bone. We report a case of an 8 month old male infant, who had an osteosarcoma involving the right proximal tibia. This patient was treated by wide excision with transepiphyseal resection and reconstruction with allograft. At 20 months after operation, the varus deformity was developed at the proximal junctional site of allograft. Thereafter, the revision was performed with correction of deformity and augmentation with the proximal fibula transfer. At 51 months after operation, he has been remained as free of disease, and he has recovered the knee motion ranged from 15 degree to 75 degree. The osteosarcoma in infant is very rare but it should be considered the osteosarcoma in the differential diagnosis of any bone lesion. Instead of amputation, the limb sparing operation and the solutions for limb length inequility in growing period should be carefully considered in the infantile osteosarcoma.