• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.399-408
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• 2008

Mobile WiMAX provides wireless broadband services for data communication based on IP protocol. The limitation of physical bandwidth in the radio links may cause performance degradation in providing wireless broadband services in WIMAX. To enhance the efficiency of the radio link utilization, Payload Header Suppression (PHS) is defined as an optional header compression mechanism for mobile WiMAX. It has, however, a very limited compression capability since it has very restrictive compression fields. In this paper, hence, we assumed the application of Robust Header Compression (ROHC), a header compression scheme proposed for links characterized by high bit error ratios, long round-trip times (RTT), and scarce resource, to Mobile WiMAX, and studied its performance. Previous studies on ROHC performance merely focused on the impact of high bit error rate. However, bit error is virtually transparent to ROHC in the wireless systems like WiMAX, since the MAC provides the bit error checking function. In order to evaluate the performance of ROHC in the Mobile WiMAX environments, therefore, we evaluated the performance of ROHC with respect to the packet losses instead of bit error. We investigated the impact of the ROHC parameters that are recommended for the implementation in the ROHC and compared the performance of ROHC with PHS.

• Journal of the Korean Institute of Gas
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• v.18 no.6
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• pp.7-13
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• 2014

As the interest on the air pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward various main issues : whether PM emissions should be regulated for diesel and gasoline vehicles and whether gasoline and LPG powered vehicles can be further neglected from PM emission inventories. Finally, the greenhouse gas ($CO_2$, $CH_4$, $N_2O$) regulation has been discussed including automotive emission regulation. The greenhouse gas and emissions (PM) particle of automotive had many problem that cause of ambient pollution, health effects. This paper discussed the influence of LPG fuel on automotive cold startability and exhaust emissions gas. Also, this paper assessed emission characteristics due to the test temperature. These test temperature were performed by dividing the temperature of the test mode and the lowest local temperature in winter. Through this study, the correlation of cold startability, exhaust emission and greenhouse gas emission was analyzed.

• The Korean Society of Law and Medicine
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• v.18 no.2
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• pp.105-138
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• 2017

This is case comments of several representative legal cases regarding self- determination right of patient. In a case in which an intoxicated patient attempted suicide refusing treatment, the Supreme Court ruled that the medical team's respect for the patient's decision was an act of malpractice, and that in particular medical situations (medical emergencies) the physician's duty to preserve life supersedes the patient's rights to autonomy. Afterwards, at the request of the patient's family, and considering the patient's condition (irrecoverable death stage, etc.) consistent with a persistent vegetative state, the Supreme Court deduced the patient's intention and decide to withdraw life-sustaining treatment. More recently, regarding patients who refuse blood transfusions or other necessary treatment due to religious beliefs, the Supreme Court established a standard of judgment that can be seen as conferring equal value to the physician's duty to respect patient autonomy and to preserve life. An empirical study of legal precedent with regard to cases in which the physician's duty to preserve life conflicts with the patient's autonomy, grounded in respect for human dignity, can reveal how the Court's perspective has reflected the role of the patient as a decision-making subject and ways of respecting autonomy in Korean society, and how the Court's stance has changed alongside changing societal beliefs. The Court has shifted from judging the right to life as the foremost value and prioritizing this over the patient's autonomy, to beginning to at least consider the patient's formally stated or deducible wishes when withholding or withdrawing treatment, and to considering exercises of self determination right based on religious belief or certain other justifications with informed refusal. This will have a substantial impact on medical community going forward, and provide implicit and explicit guidance for physicians who are practicing medicine within this environment.

• Journal of Korea Water Resources Association
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• v.53 no.10
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• pp.903-915
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• 2020

Long-term high-resolution hydro-meteorological data has been recognized as an essential element in establishing the water resources plan. The increasing demand for spatial precipitation in various areas such as climate, hydrology, geography, ecology, and environment is apparent. However, potential limitations of the existing area-weighted and numerical interpolation methods for interpolating precipitation in high altitude areas remains less explored. The proposed PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) model can produce gridded precipitation that can adequately consider topographic characteristics (e.g., slope and altitude), which are not substantially included in the existing interpolation techniques. In this study, the PRISM model was optimized with SCEM-UA (Shuffled Complex Evolution Metropolis-University of Arizona) to produce daily gridded precipitation. As a result, the minimum impact radius was calculated 9.10 km and the maximum 34.99 km. The altitude of coastal weighted was 681.03 m, the minimum and maximum distances from coastal were 9.85 km and 38.05 km. The distance weighting factor was calculated to be about 0.87, confirming that the PRISM result was very sensitive to distance. The results showed that the proposed PRISM model could reproduce the observed statistical properties reasonably well.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.227-235
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• 2019

This study monitored Daecheong 1-bo, Daecheong-stream, which carried out the project in 2014, from 2015 to 2016. The technology applied to the stream was evaluated using Periphytic Algae to check contamination indicators and ecological health of the area with an integral river-bed protection using non-toxic materials. The water quality of the monitoring section was confirmed to be above the river environment standard (II), and it was confirmed that the Saproxenic taxa of the river bed protection were higher than the upper and downstream sections. The TDI, which is an index of attachment algae, was shown in the average 51.03 and 52.15 for the pilot project sections in 2015 and 2016, confirming that the index is of the "normal" grade. This is the other sections in the upstream and downstream sections showed higher than "bad", which is thought to have a positive effect on the habitat of the river ecosystem components, especially the microbial population in river bed protection.

• Journal of Korean Society of Forest Science
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• v.95 no.6
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• pp.672-679
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• 2006

Postharvest nut quality, and changes of soluble solids content and kernel hardness during cold storage in 13 Korean prevailing chestnut cultivars were investigated to establish the chestnut grading and standardization for marketing and processing industry. Chestnut quality attributes such as nut weight, soluble solids content, kernel hardness, % with the pericarp split, and % of polyembryonic nuts were measured from 2001 to 2005. There were significant difference among cultivars in quality characteristics, and also annual variation within same cultivar, corresponded to the high genetic and environmental variability. During cold storage at $2^{\circ}C$ for 16 weeks, remarkable changes in soluble solids content were observed, and Isseumo showed the highest increase of 8% at 16 weeks of cold storage compared with postharvest. In case of most cultivars except early ripening cultivars, soluble solids content of chestnut increased until 12 weeks during cold storage, followed by decreased gradually thereafter. Kernel hardness of most cultivars except lshizuchi during cold storage increased slightly, but it was not statistically significant. This work would be a useful reference to the quality of each chestnut cultivar for the growers and breeders alike.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.21-26
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• 2009

Polycyclic aromatic hydrocarbon(PAH) contents were evaluated in sesame oils from sesame seeds of different origins and in commercial samples using HPLC with fluorescence detection. The sesame seeds, which had been harvested from India, China, and Korea, were roasted at $250^{\circ}C$ for 25 min, and the commercial sesame oils were purchased from a local market. The recoveries for eight PAHs spiked into the sesame oils ranged from 80.2 to 99.2%. The mean levels of total PAHs in the sesame oils harvested from China, Korea, and India were 3.97, 1.57, and 1.20 ${\mu}g$/kg, respectively. The PAH contents in the commercial sesame oils ranged from 0.79 to 2.15 ${\mu}g$/kg.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.176-176
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• 2017

배수시설 내 맨홀에서의 과부하 흐름은 관거시설의 배수 능력을 저하시켜 우수의 역류로 인한 도시 침수피해의 가중 요인이 된다. 특히, 도시 유역 중 하류부의 저지대에서 주로 설치되는 합류 맨홀은 저지대 침수에 많은 영향을 미치므로 합류맨홀에서의 흐름특성 분석 및 유입유량 변화에 따른 손실계수의 변화에 관한 연구가 필요한 실정이다. 현재까지 중간맨홀, $90^{\circ}$ 접합맨홀 및 3방향(T형) 합류맨홀 등에 관한 연구는 지속적으로 수행되고 있으나 4방향 합류맨홀에 관한 연구는 기초적인 연구만 수행되고 있다. 4방향 합류맨홀은 세 개의 유입관과 한 개의 유출관으로 구성되어 있으므로 각 유입관의 유입유량 변화에 따라서 맨홀에서의 손실계수가 다양하게 변화된다. 이와 같은 유입유량 변화에 따른 맨홀 내 흐름특성 분석 및 손실계수 산정에 관한 연구는 국내에서는 전무한 실정이다. 그러므로 유입유량 변화에 따른 4방향 합류맨홀에서의 손실계수 변화특성의 분석이 필요하다. 본 연구에서는 4방향 사각형 합류맨홀에서 세방향에서 유입되는 각 유입유량의 유입비($Q_{in}/Q_{out}$)가 0.0~1.0으로 변화하는 조건에서 평균 손실계수를 산정하기 위하여 하수도시설기준(환경부, 2011)의 표준 1호 맨홀 및 연결관경을 1/5로 축소하여 수리실험 장치를 제작하였다. 유출유량은 $3{\ell}/sec$이고 각 유입관(주유입관 및 좌 우측면유입관)의 유입유량을 $0{\sim}3{\ell}/sec$까지 유입유량의 비율을 각각 10%씩 변화시키면서 수리실험을 실시하였다. 실험결과 주관거의 유입유량이 줄어들고 측면관거의 유입유량이 늘어나면서 손실계수가 상승하는 것으로 나타났으며, 한쪽 측면 관거에서만 유입유량이 들어오는 $90^{\circ}$ 접합맨홀의 형태에서 손실계수가 가장 크게 나타났으며, 유입유량 변화에 따른 4방향 합류맨홀에서의 손실계수의 범위는 0.5~1.7으로 산정되었다. 이는 과부하 4방향 사각형 합류맨홀에서는 측면 유입관에서의 유입유량의 증가에 따라 평균 손실계수 값이 크게 증가되는 것으로 판단된다. 이는 김정수(2010) 등이 산정한 $90^{\circ}$ 접합맨홀의 손실계수 및 중간맨홀의 손실계수와 유사하게 나타났으므로 전체적인 손실계수의 범위는 타당하다고 판단된다. 또한, Wang(1988) 등의 유사연구와의 유입유량 변화에 따른 손실계수의 변화 경향도 유사하였다. 따라서 본 연구에서 산정된 유입유량 변화 조건이 고려된 4방향 합류맨홀에서의 손실계수는 XP-SWMM 등의 부정류 흐름이 고려된 도시지역의 침수해석이나 관거 배수능력 평가에 활용이 가능할 것으로 판단된다.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.1
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• pp.33-38
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• 2019

Thermal power generation accounts for the highest percentage of domestic power generation, among which coal-fired boiler generation accounts for the highest percentage. Coal boilers generate harmful substances and fine dust during coal combustion and have a serious effect on air pollution. So, fluidized-bed boilers have been introduced as eco-friendly coal boilers. It uses a fluid medium which affect the combustion temperature of coal. Because of it fluidized-bed boilers emit less pollutants than original one. Water-wall tubes play an important role in this fluidized bed boiler. Due to the fluid medium, the wall damage is more severe than the existing boiler. However, there is no quantitative maintenance technique in Korea yet. Remote field eddy current testing is a non-destructive evaluation technique that is often used for inspection of inner and outer wall of tube. it can inspect with non-contact and high speed. However, it is an inspection that proceeds from inside the pipe, and the water-wall tube is not able to enter the interior. In this study, we designed and simulated an external remote field eddy current sensor suitable for water-wall tube of a fluidized - bed boiler using simulations. By obtaining a signal similar to the existing remote field eddy current test, the criteria for the external remote field eddy current sensor design can be presented.

• Korean Journal of Psychosomatic Medicine
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• v.28 no.2
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• pp.99-107
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• 2020

Fibromyalgia is a disorder characterized by the core symptom of chronic widespread pain, along with fatigue, sleep disturbances, mood changes, and cognitive difficulties. The etiology of fibromyalgia involves a combination of biological factors, such as genetic vulnerability, alterations in pain processing and stress response system ; psychological factors, such as anxiety, depression, anger, and perceived stress ; environmental factors, such as infections, febrile diseases, and trauma. Central sensitization, which is amplified in the process of sensory stimulation, has been emphasized as a key etiological factor, as supported by enhanced wind-up, delayed aftersensation, decreased nociceptive flexion reflex threshold and functional imaging studies. Several guidelines recommend that a multimodal approach be used to treat fibromyalgia, including both pharmacological and non-pharmacological treatments, tailored to each individual, and that clinicians should provide an intellectual framework through sufficient education and emphasis on the importance of self-management. The prevalence of mood disorders, anxiety disorders, and other psychiatric problems is 7-9 times higher in patients with fibromyalgia than in the general population ; moreover, the association between fibromyalgia and certain psychopathologies or sleep problems has also been suggested. Since psychiatric problems, with shared vulnerabilities and risk factors, interact with fibromyalgia bidirectionally and also affect the disease course, an integrated management approach is needed to determine the risk of comorbidities.