Study of the tidal dynamics of the Korea Strait using the extended Taylor method

The Korea Strait (KS) is a major navigation passage linking the Japan Sea (JS) to the East China Sea and Yellow Sea. Almost all existing studies of the tides in the KS employed either data analysis or numerical modelling methods; thus, theoretical research is lacking. In this paper, we idealize the KS–JS basin as four connected uniform-depth rectangular areas and establish a theoretical model for the tides in the KS and JS using the extended Taylor method. The model-produced K1 and M2 tides are consistent with the satellite altimeter and tidal gauge observations, especially for the locations of the amphidromic points in the KS. The model solution provides the following insights into the tidal dynamics. The tidal system in each area can be decomposed into two oppositely travelling Kelvin waves and two families of Poincaré modes, with Kelvin waves dominating the tidal system. The incident Kelvin wave can be reflected at the connecting cross section, where abrupt increases in water depth and basin width occur from the KS to JS. At the connecting cross section, the reflected wave has a phase-lag increase relative to the incident wave of less than 180∘, causing the formation of amphidromic points in the KS. The above phase-lag increase depends on the angular velocity of the wave and becomes smaller as the angular velocity decreases. This dependence explains why the K1 amphidromic point is located farther away from the connecting cross section in comparison to the M2 amphidromic point.

Gambaran Estimasi Usia Biologis dengan Menggunakan Metode Blenkin-Taylor (Modifikasi Sistem Demirjian) di Kota Semarang

Unexpected incident such as natural disaster and accident often occur in many countries including Indonesia which causes many victims with unknown identity. Tooth is one of the indicators to assess and determine a person's identity. Blenkin-Taylor method is used for age estimation of an individual by using teeth. This study was aimed to obtain the estimation of biological age by using Blenkin-Taylor method in Semarang. This was a descriptive study with a cross sectional design. Samples were panoramic digital radiograph data of patients aged 5-15 years, copied in the form of a soft file. The observation and measurement were performed on seven teeth of right lower jaw by using the DICOM RadiAnt application. Data of observations and measurements of maturation scores were calculated and converted into the Blenkin-Taylor formula to determine the biological age. The results showed that the difference between biological and chronological age was ±0.32 years. This value was lower than the Blenkin-Taylor previous study result which was ±0,6 years. In conclusion, by using the Blenkin-Taylor method, there was a difference between biological age and chronological age as many as ±0,32 years in individuals aged 5-15 years old in Semarang.Keywords: biological age, the Blenkin-Taylor method, panoramic radiography Abstrak: Kejadian tidak terduga seperti bencana alam dan kecelakaan sering terjadi di berbagai negara, salah satunya di Indonesia yang menimbulkan banyak korban jiwa yang tidak diketahui identitasnya. Gigi merupakan salah satu indikator untuk menilai dan menentukan identitas seseorang. Salah satu metode dalam menentukan estimasi usia dengan menggunakan gigi ialah metode Blenkin-Taylor. Penelitian ini bertujuan untuk mendapatkan gambaran estimasi usia biologis dengan menggunakan metode Blenkin-Taylor di Kota Semarang. Jenis penelitian ialah deskriptif dengan desain potong lintang. Sampel penelitian ialah data file digital radiograf panoramik pasien berusia 5-15 tahun yang disalin ke dalam bentuk soft file, kemudian dilakukan pengamatan dan pengukuran pada 7 gigi regio kanan rahang bawah dengan menggunakan aplikasi RadiAnt DICOM. Hasil pengamatan dan pengukuran skor maturasi dihitung dan dikonversikan ke dalam rumus metode Blenkin-Taylor untuk menentukan usia biologis. Hasil penelitian menunjukkan bahwa selisih usia biologis dan usia kronologis sebesar 0,32 tahun. Hal ini lebih kecil dibandingkan penelitian Blenkin-Taylor terdahulu sebesar 0,6 tahun. Simpulan penelitian ini ialah dengan mengggunakan metode Blenkin-Taylor terdapat selisih rerata usia kronologis dan usia biologis sebesar ± 0,32 tahun pada individu usia 5-15 tahun di Kota Semarang.Kata kunci: usia biologis, metode Blenkin-Taylor, radiograf panoramik

Study on the Tidal Dynamics of the Korea Strait Using the Extended Taylor Method

The Korea Strait (KS) is a major navigation passage linking the Japan Sea (JS) to the East China Sea and Yellow Sea. Almost all existing studies on the tides in the KS employed either data analysis or numerical modelling methods; thus, theoretical research is lacking. In this paper, we idealize the KS-JS basin as three connected uniform-depth rectangular areas and establish a theoretical model for the tides in the KS and JS using the extended Taylor method. The model-produced K1 and M2 tides are consistent with the satellite altimeter and tidal gauge observations, especially for the locations of the amphidromic points in the KS. The model solution provides the following insights into the tidal dynamics. The tidal system in each area can be decomposed into two oppositely travelling Kelvin waves and two families of Poincaré modes, with Kelvin waves dominating the tidal system. The incident Kelvin wave can be reflected at the connecting cross-section, where abrupt increases in water depth and basin width occur from the KS to JS. At the connecting cross-section, the reflected wave has a phase-lag increase relative to the incident wave by less than 180°, causing the formation of amphidromic points in the KS. The above phase-lag increase depends on the angular frequency of the wave and becomes smaller as the angular frequency decreases. This dependence explains why the K1 amphidromic point is located farther away from the connecting cross-section in comparison to the M2 amphidromic point.