• Journal of the Korean Society of Radiology
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• v.81 no.2
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• pp.351-364
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• 2020

Missed lung cancers on chest radiograph (CXR) may delay the diagnosis and affect the prognosis. CXR is the primary imaging modality to evaluate the lungs and mediastinum in daily practice. The purpose of this article is to review chest radiographs for common blind spots and highlight the importance of various radiologic presentations in primary lung cancer to avoid significant diagnostic errors on CXR.

• Tuberculosis and Respiratory Diseases
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• v.60 no.3
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• pp.277-284
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• 2006

Background : Delayed treatment of pulmonary tuberculosis is an important problem because it results in greater mortality and the nosocomial transmission of tuberculosis. This study was conducted to analyze the factors that contribute to the delayed treatment of pulmonary tuberculosis in a university hospital and we wanted to provide basic data for instituting an effective management program for tuberculosis. Methods : we retrospectively reviewed the medical records of 155 patients with smear-positive or culture-positive pulmonary tuberculosis and who were treated between May 1999 and October 1999. A case-control study was performed to analyze the factors. We then tried to follow up the patients in delayed treatment group via telephone for the purpose of assessing the therapeutic interventions. Results : Among 150 patients, 55 (37%) were included in the delayed treatment group. The factors associated with delayed treatment on the univariate analysis included age (61 vs 40 years old; p <0.001), a smear-negative sputum test for acid-fast bacilli (AFB) (85% vs 55%; p <0.001) and no visits to a private clinic before the patient presented to the university hospital (56% vs 36%; p = 0.014). Multivariate analysis revealed that old age (p = 0.001), a smear-negative sputum for AFB (p = 0.001), and lower lobe infiltrate on chest X-ray (p = 0.041) were the independent predictors of delayed treatment. Of the 22 patients who did not receive any treatment, 20 of them 91%) consented to our suggestion of revisiting the hospital. Conclusion : Delayed treatment of patients with pulmonary tuberculosis is not uncommon in a university hospital. Old age, smear-negative for AFB, and lower lobe infiltrate on chest X-ray are the risk factors for delayed treatment. A more systematic management system is required for achieving better control of tuberculosis.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.694-699
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• 2007

Delayed tooth eruption is the most commonly encountered deviation from normal eruption time. Racial, ethnic, sexual, and individual factors can influence eruption and are usually considered in determining the standards of normal eruption. Delayed tooth eruption was affect to the dentition and facial growth, so that when it occurred careful evaluation should be performed to establish the cause and the treatment plan accordingly. Present 3 cases of delayed tooth eruption by periapical lesion, underdevelopment of incisior and compound odontoma were successfully treated. In these cases, we could observe spontaneous eruption of the delayed erupting tooth after removal of interrupting factor and space regaining with maintaining.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.285-285
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• 2015

댐 및 저수지 시설물은 노후화나 안전성 미확보로 인한 파손 또는 붕괴 발생 시 하류부에 막대한 인명과 재산피해 등 치명적인 결과를 초래하게 된다. 이러한 대형 안전사고를 예방하고자 시설물의 안전관리에 관한 특별법에서는 댐 시설물을 규모별로 1, 2종 시설물로 구분하고, 이에 대해 주기적으로 안전점검 및 정밀안전진단을 실시하도록 제도화하는 한편 진단 결과에 따라 보수 보강 등의 안전조치를 의무화하고 있다. 구조물 결함에 따른 보수 보강은 보수재료와 공법 선정시 공법의 적용성, 구조적 안전성, 경제성 등을 종합적으로 검토하여 결정하여야 한다. 손상 부위에 대한 보수 보강은 제한된 예산과 인력을 효율적으로 투자하기 위해 보수재료 및 공법의 선정 뿐만 아니라 보수 보강이 이루어져야 하는 부재에 대한 우선순위를 산정하는 것이 최우선적으로 선행되어야 한다. 안전점검 및 정밀안전진단 세부지침에서는 보수 보강 대책 마련 시안전점검 및 정밀안전진단 결과를 기초로 하여 적정 재료 및 공법을 선정하고, 보수 보강의 수준 및 우선순위를 결정하도록 명시되어 있다. 하지만 우선순위 결정에 대한 가이드라인이 부재하여 불필요한 시공과 비효율적인 예산 투입으로 인해 국가예산의 낭비되고 시설물의 안전까지 위협받게 되는 경우가 발생하고 있다. 따라서 본 연구에서는 시설물의 상태에 따른 적절한 보수 보강 필요성을 판단하고 보수 보강 수준 및 우선순위를 결정하기 위한 방법론을 개발하였다. 댐 시설물에 대한 안전점검 및 정밀안전진단의 종합평가는 평가대상 개별시설에 대하여 상태 평가 및 안전성 평가를 실시한 후 그 결과에 의해 산출된 상태평가지수와 안전성평가지수를 비교하여 평가단계별로 그 결과를 취합하여 종합평가를 실시하고 있다. 따라서 상태평가에 의해 산정된 종합평가 결과를 이용하여 개별 부재의 상태평가값 산정을 위해 하부 단계의 가중치 및 평가 지수 역산하고, 재산정된 가중치 및 평가지수를 이용하여 각 부재에 대한 보수 보강 우선순위를 산정하고자 하였다. 개발된 방법론은 점검 진단 책임기술자 및 시설물 관리주체 담당자가 댐 시설물의 개별부재에 대한 보수 보강 실시 여부를 판정할 수 있는 기준으로, 보수 보강에 대한 정책 결정시 경제성을 고려한 신뢰도 있는 기준으로 활용될 수 있을 것으로 기대된다.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.39-43
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• 2008

Purpose: There are various methods to diagnose hemangioma, such as ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine. However, by development of SPECT imaging, the blood-pool scan using $^{99m}Tc$-labeled red blood cell has been used, because it was non-invasive and the most economical method. Therefore, in this study, we proposed that the usefulness of $^{99m}Tc$-RBC scan and SPECT of the head and neck to diagnose unlocated hemangiomas. Materials and Methods: $^{99m}Tc$-RBC scan and SPECT was performed on 6 patients with doubtful hemangioma (4 person, head; 1 person, neck; 1 person, another). We labeled radiopharmaceutical using modified in vivo method and then, centrifuged it to remove plasma. After a bolus injection of tracer, dynamic perfusion flow images were acquired. Then, anterior, posterior, both lateral static blood-pool images were obtained as early and 4 hours delayed. SPECT was progressed 64 projections per 30 seconds. Each image was interpreted by physicians, Nuclear medicine specialist, and technologist blinded to patient's data. Results: In 5 patients of all the radioactivity of doubtful site didn't change in flow images, but, in blood-pool, delayed and SPECT images, it was increased. So, it was a typical hemangioma finding. The size of lesion was over 2 cm, and it could discriminate as comparing to the delayed and SPECT imaging. On the other hand, in 1 patient, the radioactivity was increased in blood-pool images, but, not in delayed and SPECT images, so, it was proved no hemangioma. Conclusion: Using $^{99m}Tc$-RBC Scan and SPECT, we could diagnose the hemangiomas in head and neck, as well as, liver, more non-invasive, economical, and easy. Therefore, it considered that $^{99m}Tc$-RBC scan and SPECT would offer more useful information for diagnosis of hemangioma, rather than otherimaging such as US, CT, MRI.

• Tuberculosis and Respiratory Diseases
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• v.59 no.5
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• pp.473-479
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• 2005

Background : A pulmonary embolism often presents with nonspecific symptoms and signs. However, a delayed diagnosis can result in catastrophic outcome. The majority of preventable deaths associated with a pulmonary embolism can be ascribed to a missed diagnosis rather than to the failure of existing treatments. Therefore, accurate and rapid diagnostic methods are essential for the management of a pulmonary embolism. The recent generation of multidetector-row spiral CT scanners appears to outperform other imaging modalities in detecting a central and peripheral pulmonary embolism. However, there are some variations in the interpretations of the findings between observers. This study examined the inter-observer differences of the diagnoses in patients with a pulmonary embolism. Method : 64 patients who were diagnosed with a pulmonary embolism either clinically or with spiral chest CT from 2002 to 2004, were included. Two thoracic radiologists interpreted the multidetector-row spiral CT in terms of the diagnosis of a pulmonary embolism and the location of the thrombus independently. Among 64 patients, 14 patients were excluded because there was no evidence of a pulmonary embolism or there was different interpretation of the pulmonary embolism between radiologists. A clinical diagnosis was based on "Rules for predicting the probability of embolism". Results : The mean score of the patients according to the Wells method was $3.91{\pm}0.30$ (0-9). The accordance of the radiologists was 95% in the main, 85% in the lobar, 91.2% in the segmental, and 96% in the sub-segmental pulmonary arteries. After excluding the negative interpretation from both radiologists, their agreement was 76.2%(${\kappa}.$ 0.83) in the main, 57.6%(${\kappa}.$ 0.63) in the lobar, 51.5%(${\kappa}.$ 0.63) in the segmental, and 34.6%(${\kappa}.$ 0.49) in the sub-segmental pulmonary arteries. Conclusion : Chest CT has been recently applied to patients suspected of having a pulmonary embolism. It was found that spiral CT is a rapid test for diagnosing a thrombus, and there was reliable accordance between the observers from the area of the large pulmonary arteries. However, there was a lack of agreement between the observers in diagnosing thrombi located distal to the sub-segmental arteries.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.199-200
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• 2011

중증외상 환자의 사망률을 높이는 출혈의 형태에는 정맥손상으로 인한 출혈과 골절 및 장기손상에 의한 동맥손상 출혈, 골수 내 출혈이 있을 수 있는데, 이중에서 동맥손상에 의한 출혈은 진단이 지연되면 다량의 출혈로 인한 생체활력 징후가 불안정하며 사망률이 높아지는 아주 중요한 질환이다. 응급실을 내원한 중증외상 환자로 등록된 환자 중 혈관조영술을 시행 받고, 동맥 파열이 진단되어 동맥색전술을 시행 받은 환자를 대상으로 생존의 영향을 미치는 인자에 대하여 알아보고자 하며 생존 군과 사망 군을 비교하여 동맥촬영 및 색전술이 적절한 치료방법으로 유용성과 적절한 시행시점을 연구하기 위함이다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.130-133
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• 2006

본 연구에서는 진단분야에서의 시스템의 성능을 향상시키고 최적의 해를 찾고자 사례기반추론과 인공 신경망을 혼합한 시스템을 제안한다. 사례기반추론은 과거의 사례(경험)를 통해 현재의 제시된 문제를 해결하는 추론방식으로, 지식이 획득이 덜 복잡하고, 정형화되기 어려운 규칙이나 문제영역이 불분명한 분야에 효율적으로 활용되었다. 그러나 사례의 양이 방대해야 효율적인 추론을 할 수 있으며, 검색된 시간 또한 지연되는 단점이 있다. 이러한 문제를 보완하고자 본 논문에서는 인공 신경망의 학습을 통해 저장된 ANN Library를 생성하여, 사례기반추론에서의 부적절한 해를 유추하는 것을 방지하고, 효율적이고 신뢰성이 높은 해를 유추해 내는데 목적이 있다.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.19-21
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• 2009

The reflectometry for locating the fault at a cable is the same as a problem estimating the time delay between the incident and the reflected signals. In this paper, we propose a method for estimating the time delay between the two signals. The proposed method is based on the modeling of the Gaussian enveloped linear chirp signal in the Gaussian noise environment. The phase and the instantaneous frequency of the received signal are estimated by linear Kalman filtering. From the estimated instantaneous frequency, we can measure the time interval between the center frequencies of the incident and the reflected signals. The time interval is the same as the time delay between the incident and the reflected signals. In a simulation assuming that the cable has open fault at the end of the cable, the proposed method showed a good result in estimating the time delay.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.7 s.100
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• pp.781-787
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• 2005

The correlation dimension can provide some intrinsic Information of an underlying dynamic system by reconstructing measured nonlinear time series. The vibration signals measured from a rotor with different clearance sizes between shaft and bushing were analyzed using the correlation dimension. The results showed that the correlation dimension can identify the size of the clearance of a rotor and the lubricating condition, which can not be analyzed by frequency spectrum or wavelet. The magnitude of the correlation dimension became smaller as the clearance larger and as the lubrication condition better.